Mauna Kea Cloudforest Posted January 13, 2014 Report Share Posted January 13, 2014 This was found posted on a website and summarizes a lot of cold hardiness data. Reposting this here for general availability. reprinted from "The Palmateer" Dec., 1999 My main purpose in tackling this particular subject is to demonstrate to palm growers (the hobbyist & the commercial grower alike) the vast array of palms that can be grown with a little effort in central Florida. However it is necessary to preface a subject this "all encompassing" with a few of the obvious disclaimers, the first being micro-climates : lakes and other waterways to the north or north west of our gardens, tall plants that can provide windbreaks and large oak trees or other evergreens to provide a canopy which helps deter frost from settling on anything underneath. Any of us lucky enough to have these examples in our gardens can surely attest to their advantages. In order for this to remain a newsletter article and not a book I have refrained from noting any of the surroundings of the palms listed in the following table. The other caveat in reporting on something as subjective as this is that there really are no standard "rules" when it comes to freezes in our corner of the world. It seems that nearly every freeze is somehow different in it's own way, be it a low temperature reading, the amount of frost, it's duration and more importantly, the damage (or lack of) left behind. So what I have attempted to do is collect the results of several different freezes from several different areas over a period of time, then fuse them into one table, kind of an EKG for palms if you will. The only limit I had to deal with was the actual information that is published; there just isn't a whole lot out there but fortunately there is enough to give us all some guidelines on most species.And that is exactly what this article is - a guideline and nothing more. There will be a few readers whose results were different, maybe even totally opposite from what is published here and that's to be expected from such a diverse topography as central Florida. This article tallies results from specific freezes and no others. Just because a Ptychosperma listed here died @ 25 Fahrenheit (hereon referred to as F) degrees doesn't mean it will die @ 25F degrees in your garden, just fair warning that it could. On the opposite spectrum I know of several large Bismarckia nobilis located in warmer winter locales than Orlando, and they sometimes suffer severe damage at temps in the high 20's while several large specimens in Orlando barely burn at 23F. So it would be silly to suggest that anyone totally eliminate any attempts to grow a palm based on this table nor should it be used to decide on planting a row of something marginal in the front yard. If the table indicates a palm that may be somewhat of a risk for you then plant just one or two of them, observe their progress then decide. There are plenty of factors involved when considering a palm's cold hardiness. For instance the length of time the palm has been in the ground is very important. A well established planting of two summers or more will rebound from cold damage faster than a newly planted palm. The type of treatment the palm received is extremely important. Was it a well-cared for and strong growing specimen or nutrient deficient and weak from the beginning? After the freeze was the correct fungicide application rendered, did it live for awhile only to die from insect damage to the weakened bud, was it subject to prolonged cold spells before or after the freeze? None of those items are noted (newsletter vs. book again). The actual size of the palm also plays a part with some of the larger growing species. Thicker stems can help to insulate the irreplaceable growing point. Larger specimens usually have lots of fronds already formed in their bud, and thus are able to recover much faster than a smaller palm or seedling. The last factor to consider is that some palms can recover nicely from one freeze but what happens if they are hit with a 2nd blast the following winter? Or separate freezes during the same winter? If you look at the data carefully you will notice some of those results. For the purposes of this article a freeze is considered to be any time when the low temperature has reached 32F. In the past 100 years there have been 54 freezes "officially" recorded in Orlando and Tampa combined. Twelve of them recorded lows of 29F or higher. These freezes are known as advective or advection freezes. They are caused by cold air masses being pushed into Florida by the polar jet stream. These air masses usually form in Canada with the truly frigid ones originating from as far away as Siberia. When a freeze occurs during the 1st night of a cold front it is almost always an advective freeze. These are rarely able to kill an established, healthy palm. Unfortunately the sudden drop in temperature will usually chill the moisture in the air which in turn forms frost. A little frost for an hour or so may cause some slight cosmetic damage to palm foliage but when moving in on the heels of warm, humid weather heavy frost can occur. Most tropical species can be completely defoliated unless under a protective canopy or other covering. Sometimes the accompanying winds can delay the settling of frost for most of the night by forcing the warm air radiated from the ground back down to the surface. Freezes with a low reading in this range are also of short duration (usually 3 hours or less below 32F). Of the past 100 years twenty eight freezes had lows in the 28F - 24F range. It is at these temperatures that actual cold damage occurs and in some of the species with more tropical origins, death can be the result as well. A few of these lows can be attributed to advective freezes but the vast majority can be termed as a radiation freeze. This type occurs on the 2nd night of a cold front. In a nutshell there are usually no winds to delay frost settling and no cloud cover to help trap heat to the ground. Thus any heat attained during the day is lost, radiated into the atmosphere and a cooling occurs at ground level as well as an adjacent layer of air around it. When these conditions are forecast, protective covering is a must to minimize or prevent foliage damage for all but the hardiest species. The remaining fourteen freezes from the past 100 years had lows of 23F or less. These "hard" freezes are usually not the norm for most of central Florida but when they do occur, all bets are off regarding most palms' chances to escape any damage and in some cases survive at all. Even some of the most hardy and widely planted species (e.g. Syagrus romanzoffiana) can suffer severe damage or death if not properly maintained. Nevertheless the table identifies more than a few species which can survive hard freezes including several which at this time are not widely planted but deserve to be so, if for nothing else than their ability to withstand this type of cold. Mathematically, the chances of a severe or hard freeze occurring averages out to once every 7 to 8 years. You can adjust this figure to fit your location. For example draw a line from Tampa to Daytona. North of the line it is usually colder, south of it will be warmer with some coastal areas perhaps going well over a decade or longer without a hard freeze. There are also some areas known as "cold pockets" throughout our region. The best known is a large section with borders roughly west of Hwy. 27, east of I-75, south of I-4 and north of Lee county. When considering your location, remember that water does not cool as rapidly as land so wet areas have averaged 3 degrees warmer than dry areas. Also cold air is denser than warm air so it collects in pockets at the bottom of hills. Thus the eastern "half" of the state always cools slower than the western half. This has held true for both coasts as well as inland. As more and more species become available for purchase this type of report can be expanded upon in greater detail as well as narrowed to specific areas (Orlando only, Tampa only, and so on). Each freeze can be isolated, the results broken down and noted for posterity. With the advent of the Internet, e-mail, etc. more and more information can be easily shared in the future and hopefully it will be. But for now this will have to do. All information gathered was collected from various past copies of our local newsletter, records from my garden in Orlando and finally two separate reports originally published in Principes by our own local palm pioneer/forefather, Dent Smith. From reading his findings and viewing other member's gardens I have been motivated to try and grow as many different palms as possible all the while realizing that their presence on earth can be as temporary as my own. So go outside, grab a shovel and start digging! LIST OF GARDENS WHERE DATA WAS RECORDED ORLANDO - my garden; approx. 95% of all plantings in open areas (no canopy) 1/99 28F low; 8 hrs below freezing; moderate frost in open areas 1/97 : 26F low, 7 hrs below freezing; heavy frost in open areas 2/96 : 23F low; 10 hrs. below freezing; heavy frost in open areas, minor under oak canopy 1/96 : 27F low; 5 hrs. below freezing; heavy frost in open areas 12/95 : 29F low; 3 hrs. below freezing; moderate frost in open areas 2/95 : 25F low; 6 hrs. below freezing; heavy frost in open areas; very little under oak canopy 12/89 = ALL OF CENTRAL FLORIDA two consecutive freezes - 12/24 & 12/25 : lows to 23F along much of the Atlantic coast with lower readings inland; highs into the 30's/lower 40's the next day, lows ranging from 30F to 25F the following evening. DAYTONA BEACH 12/12/62 : 22F low; approx. 14 hrs. below freezing 12/13/62 : 26F low; approx. 11 hrs. below freezing 12/14/62 : 29F low; approx. 3 hrs. below freezing DAYTONA BEACH 12/12/57 : 25F low 12/13/57 : 27F low 1/9/58 : 27F low 2/17/58 : 29F low 2/18/58 : 26F low 2/19/58 : 26F low 2/20/58 : 29F low SUMMATIONS OF HOW VARIOUS PALMS FARE IN CENTRAL FLORIDA ACANTHOPHOENIX rubra (under 2 ft): killed @ 25f, Daytona ACOELORRAPHE wrightii (mature clumps, native palm): undamaged 22-23F, defoliated @ 18f, Umatilla ACROCOMIA aculeata (mature to sdlgs.): undamaged @ 28f (Orlando); defoliated @ 22f (Daytona) ACROCOMIA 'totai' (mature to juvenile): undamaged 23f (Orlando), some specimens defoliated by 19f in various locales during '89 freeze and others retained some foliage ACTINORHYTIS calapparia (7 ft): moderate foliage burn @ 28-29f (Orlando); one specimen in Cocoa Beach survived 23f w/ no permanent damage ADONIDIA merrillii (mature to 3 ft): major foliage burn/total defoliation @ 29-27f (Orlando); killed @ 25f (Daytona) AIPHANES aculeata (11 ft to 3 ft): no damage in shade, 28f low; killed in the open @ 25f (Daytona); one specimen survived 23f low @ Cocoa Beach in '89 and produces viable seed to this day. AIPHANES acanthophylla, erosa = minima (8 ft,5 ft,3 ft): defoliated @ 27f (Orl.); killed @ 25f (Daytona) ALLAGOPTERA arenaria (mature, fruiting): no damage @ 23f in Lakeland & Orlando; several specimens survived '89 lows to 20-19f w/ severe foliage burn ARCHONTOPHOENIX alexandrae (25 ft - 6 ft): no damage @ sheltered 28f (Orl.); mature palms killed @ 25f in Daytona; ARCHONTOPHOENIX cunninghamiana (16 ft- 7 ft): survived defoliation @ 25-27f; killed @ 22f, Daytona. There seems to be only a slight difference in cold hardiness between the 2 most commonly grown "King Palm" species; neither palm can be expected to survive the worst of our region's cold but planted in a protected spot they can (and are) grown to large, fruiting sizes ARECA catechu (4 ft): killed @ 25f, Daytona ARECA triandra (8 ft): killed to the ground by 22f, Daytona but as a clumping palm it consistently re-grows from the roots; no damage from shaded 29f low (Orl.) ARENGA caudata (5 ft): no damage 28f (Orl.) ARENGA engleri (9 ft & under): moderate foliage burn @ 22f (Daytona); no damage from 23f (Orl.) or a sheltered 17f (Zephyr Hills) ARENGA pinnata (mature to 7 ft): variable hardiness. Killed @ 22f in Daytona; defoliated but SURVIVED 19f in Orlando. Undamaged @ 28f (Orl.); severe burn @ 26f (Orl.) ATTALEA - several species (cohune, butyracea, speciosa) in the central region survived 1989 lows to 19f (Vero to Daytona) albeit totally defoliated; some juvenile palms have made it thru 26-28f basically undamaged BACTRIS gasipaes (6 ft): a clumping palm defoliated but re-grew from the roots (25f Daytona, 27f Orlando) BECCARIOPHOENIX madagascariensis (6 ft to 2 ft): undamaged @ 28f (Orl.); moderate burn @ 26f (Orl.) BISMARCKIA nobilis (15 ft to sdlgs.): 3 specimens undamaged @ 23f (Orl.); potted 2-leaf seedlings undamaged @ 26-27f (Orl.); defoliated/severe damage recorded on some specimens @ 22f and above (not in Orlando collection). Apparently there is some variability in hardiness, the "pure" silver form more cold hardy than the green form. BORASSODENDRON machodonis (2 ft): sheltered under an oak canopy this palm killed at 26f (Orl.); there is a larger specimen growing at the infamous Dr. Young's collection in Tampa. BORASSUS sp.: seedling ages 1 to 3 show leaf burn around 26f but recover rapidly. A large B.flabellifer growing in mainland Melbourne survived '89's 19f low as did a specimen of the larger growing B.aethiopum, also located in mainland Melbourne @ F.I.T. There are several large species @ Dr. Young's in Tampa that survived '89 as well as male & female palms located off the Indian River coast in Wabasso. The palms in Wabasso are the only fruiting pair outside of FTG in Miami ! BRAHEA SP.: in general almost all species fair poorly in our humid climates. They actually look and grow better in the winter or coldest months than during the summer. There are two notable exceptions. The first is B."clara" which some consider one and the same as B.armata. The B."clara" is not nearly as "blue" as armata with no other discernable differences. The clara palm grows faster and tolerates the humidity while armata does not. The best exception is B.brandegeei. No problems with humidity except as a very small seedling, then regular applications of any mild contact fungicide can be used but are not necessary. B.brandegeei survived lows from 19f (Melbourne) to 22f (Daytona) w/ little to no foliage damage. BUTIA capitata: a very common & useful palm, fruits are edible & tasty right off the tree. Survived lows of 17f to 19f undamaged, moderate leaf burn at 15f (Sorrento '89). CARPENTARIA acuminata: juvenile palms (under 3 ft overall) survived 28f low (under protective oak canopy) w/ no damage. Large specimens in the open have been defoliated by temps in the mid 20's. CARYOTA mitis: the most commonly planted is the clustering C.mitis. This palm was defoliated at 23f (Orlando) but since a clumper, it has regrown from the roots at a quick clip of 3 to 4 ft. per year. There are some stems that have reached maturity and fruited in the Orlando area. other CARYOTA sps.: cummingii was killed @ 25f (Daytona); C."Elvis" killed @ 26f (Leu/Orl.); ochlandra killed @ 22f (Daytona), moderately damaged as a 2 yr. old sdlg. @ 26f (Orl.); C."Himalayana" undamaged @ 26f (Leu/Orl.); urens killed @ 22f (Daytona); obtusa undamaged @ 26f (Leu/Orl.). CHAMAEDOREA sps.: the two most commonly recommended species, microspadix and radicalis have been reported to takes lows into the high teens before showing any foliage damage. Both are widely planted and used as ornamentals throughout cen.Fla. Several others were killed @ temps from 22f to 19f including ernesti-augustii, elegans, glaucifolia, klotzschiana, metallica, seifrizii; tepejilote was killed @ 25f; cataractarum, stolonifera took 26f (Orl.)w/out damage, plumosa showed burn but survived 23f (Lakeland) while klotzschiana was undamaged @ 23f. CHAMAEROPS humilis : undamaged from 23f to 17f (shaded); moderate burn @ 15f (Sorrento '89) CHAMBEYRONIA macrocarpa (3 ft): moderate foliage burn @ 26f (Orlando, shaded location) COCCOTHRINAX sps.: two species seem to stand out from the others in regards to cold tolerance. The first is the native C.argentata, showing no damage @ 23f (Orl.). There is some variability as several specimens have been reported to defoliate @ 25f to 22f. There are plenty of mature specimens in cen.Fla. The second species is C.crinita, undamaged @ 25f (Daytona). Again there is some variability, specimens w/ reports of defoliation and death @ 22f to 19f. Others : argentea, alta, barbadensis all killed @ 22-23f; miraguma burns at 27- 22f, killed @ 19f (Mel.) COCOS nucifera: tall mature palms killed at temps from 23f to 19f (Daytona to Vero). Maypan hybrids show severe burn with any frost (temps 29f on down). There are several "Jamaican Tall" varieties which handle the cold better but are highly susceptible to lethal-yellowing thus are rarely if ever planted anymore. Among those is a specimen growing on the bay in Clearwater Beach that barely survived 19f in '89 and lives to this day. COPERNICIA alba (over 7 ft): no damage @ 26f (Orl.); slight burn @ 22f (Day.); moderate burn @ 19f (Mel.). C.prunifera showed no damage @ 26f as well but was defoliated/killed by temps from 22 to 19f. Cuban COPERNICIAS: the following species survived 19f (Mel.) but were defoliated : baileyana, berteroana, glabrescens, macroglossa. No damage @ 28f (Orl.) to baileyana, berteroana, hospita, macroglossa. Slight to moderate foliage burn @ 26f for the aforementioned palms. CORYPHA umbraculifera: large specimens survived 23f lows in '89 (Vero) w/ major foliage damage. CORYPHA utan (over 6 ft): severe foliage damage at slightest frost (29 to 26f, Orlando) but always grows out quickly. CRYOSOPHILA sps (6 ft to 3ft). : two species, stauracantha formerly argentea and warscewiczii formerly albida; the former has survived temps as low as 26f albeit w/ total defoliation. The latter was killed @ 22f (Daytona) but survived 25f beforehand. DICTYOSPERMA album (7 ft to 3 ft): several cultivars exist based mostly on coloring; no difference in cold hardiness. Severe foliage damage, usually total defoliation at slightest frost (29f); large juveniles killed outright @ 25f (Daytona) DYPSIS cabadae (4 ft): small juveniles killed to the ground @ 22f (Daytona) but since it is a clustering palm they re-grew from the roots. Foliage severely damaged at light frost (27-26f, Orlando). DYPSIS decaryi (14 ft): a much tougher palm than previously thought. Defoliated @ 23f (Orl.) but quickly recovered. Slight foliage damage appears around 27f. DYPSIS decepiens: sdlg. palms @ 1.5 hgt. Survived 29f light frost unscathed in the open; have taken 26f (Orl.) showing only small cold marks on the foliage DYPSIS leptocheilos (over 6 ft): severe damage @ slightest frost (29f, Orl.); killed @ 23f (Orl.) DYPSIS lutescens: killed to the ground @ 22f (Daytona) but since it is a clustering palm they re-grew from the roots; large clumps in the open show frost burn around 29f, shaded specimens tolerate lower temps down to 26f before burning ELAEIS guineensis: mature specimens survived 19f (Mel.) w/ complete defoliation. Smaller palms show damage @ 29-28f but quickly recover in one summer EUTERPE edulis: large juvenile (7 ft) undamaged in shaded 29f (Orl.); exhibited slight damage @ 26f (Orl.) GASTROCOCOS crispa: seedlings left out survived 29f (Orl.) unscathed GAUSSIA maya over (6 ft): killed @ 25f (Daytona) but have survived defoliation @ 26f (Orlando) GUIHAIA argyrata (2 ft): undamaged @ 26f Orlando HETEROSPATHE elata (4 ft): killed @ 25f Daytona HOWEA forsteriana ((7 ft to 2 ft): killed @ 25f (Daytona); survived temps ranging from 29 to 25f w/ major foliage damage. Difficult to establish here, seems to prefer cooler temps during the summer. Burns in full sun. HYOPHORBE lagenicaulis (6 ft to 3 ft): killed @ 23f (Orl.), defoliated @ 27f, Orl.; HYOPHORBE verschaffeltii (9 ft to 3 ft): killed @ 22f (Daytona); survived defoliation @ 23f (Orl.); shows leaf burn @ 29-28f but retains some green foliage to about 26f. Much more cold hardy than the above Bottle palm HYPHAENE sps. : This genus is in dire need of revision. A shrubby species, probably H.coriacea has survived 19f albeit defoliated and takes down to 23f for major damage to appear, possibly the hardiest of the bunch. H.dichotoma (India) and H.thebaica (Africa) have also survived 19f low (Mel.) w/ total defoliation KERRIODOXA elegans (2 ft): survived 26f (Orlando) w/ moderate foliage damage; undamaged @ 28f (Orl.) LACCOSPADIX australasica (3 ft to 1 ft): survived basically undamaged @ 27f (Jacksonville); killed outright @ 23f (Orlando); probably more suitable to northern Fla. climate as opposed to central Fla. (excepting any frosts/freezes) LATANIA sps. : extremely tender as young palms, specimens ranging from 6 ft. to 3 ft. have been killed by temps @ 27-26f (Orlando); larger specimens (over 6 ft) on Merritt Island have survived one time exposures to the same temps. There is one specimen of L.loddigesii in south Brevard county that was planted circa 1930s and has survived all subsequent freezes including 19f low in 1989. LICUALA grandis (3 ft & under): killed @ 26-25f low (Orlando & Daytona); has survived 29-28f lows due to placement in shaded areas LICUALA spinosa (4 ft & under): have survived 29-28f lows undamaged (Orlando) as well as one plant surviving 22f low in Daytona while others succumbed. Also has survived 19f low in Melbourne but was frozen to the ground (new stems grew back from the roots) LINOSPADIX monostachys (3 ft): survived 27f low (Jacksonville), sheltered area LIVISTONA sps.: mature specimens of saribus, decepiens, australis, and chinensis have survived lows to 19f w/out major damage. Species mariae, mariae var. Rigida and drudei were defoliated or severely damaged at 19f but the vast majority recovered. The rigida variety is slightly hardier than mariae. Other reports: L.humilis killed @ 22f (Day.); L.carinensis was undamaged @ 25f (Sebring); L.jenkinsiana was slightly damaged @ 26f (Orl.); L.muellerii (2 ft) was killed @ 23f (Orl.) but larger palms survived 19f (Mel.) w/ major damage; recent plantings of L.inermis, L.nitida (Carnavorn Gorge) and L.fulva (Blackdown Tablelands) have survived 29-28f lows (Orl.) undamaged. L.robinsoniana was killed @ 22f (Day.); the similar growing L.rotundifolia was defoliated but recovered from 26f (Orl.) and 25f lows (Day.). One last species, L.benthamii has survived 19f low growing in coastal Indian River county. LYTOCARYUM weddellianum (5 ft to 2 ft): killed outright @ 22f (Daytona) but survived 26-25f (Orlando, Daytona) w/ minor to no damage (under heavily shaded conditions). Tough to establish but an excellent candidate for shady areas in our region. MAURITIA flexuosa (2 ft): killed @ 25f (Daytona); no damage @ 29f (Orlando) MEDEMIA argun (2 ft & under): no damage @ 29-28f (Orlando), some foliage damage only @ 27f (Jacksonville); tough to establish, foliage spots easily ala Brahea & Jubaea, but being a close relative of Hyphaene and Bismarckia it has some potential for our area. NANNORRHOPS ritchiana (3 ft): undamaged @ 22f (Daytona); another tough to establish desert palm but being of the most cold-hardy palms in the world it is certainly worth trying. Seeds are becoming more easily available than in the past. NORMANBYA normanbyi (10 ft): killed @ 22f (Daytona); very slight damage @ 29f (Orl.), in the open no less ORANIOPSIS appendiculata (2 ft): killed @ 26f (Orlando) in a protected area; possibly the slowest growing palm on Earth PARAJUBAEA cocoides (2 ft): undamaged by temps ranging from 27F (Orlando) to 25f (Daytona); winter lows do not cause the problems as much as summer highs and a constantly high level of humidity. PHOENIX sps. : The following species have been recorded as being undamaged by 19f lows and thus are considered perfectly suitable for our region: P.canariensis, P.sylvestris, P.dactylifera. The sylvestris palm is much more tolerant of our humidity levels and is a better choice for most Florida gardens than canariensis or dactylifera. The next group ranked by cold hardiness: P.reclinata, P.loureirii (formerly hanceana) and P.pusilla (AKA zeylanica); those 3 species can be (and in many collections were) slightly to moderately damaged by the same 19f lows but quickly recovered during the subsequent summer. P.reclinata is becoming naturalized in a few consistently wet areas of the region. The next group would be P.rupicola and P.roebelenii, each palm was killed @ 19f (Melbourne, Orlando). Both palms seem to be equal in hardiness, being able to recover from lows in the mid 20s (in some gardens as low as 23-22f, where both species will defoliate but have been recorded as surviving, albeit barely). P.paludosa was killed by 26f low (Orlando) and seems to be the least cold hardy of all the Phoenix palms. P.theophrasti is a basically a slightly less hardy version of P.dactylifera. PHYTELEPHAS macrocarpa, seemanii (2 ft): killed @ 25f (Daytona) PINANGA kuhlii (4 ft): totally defoliated @ 26f (Orlando); killed to the ground @ 22f (Daytona) but as a clustering palm it developed new stems from the roots. A worthy subject for protected, shady areas. POLYANDROCOCOS caudescens (3 ft): killed @ 22f (Daytona); small seedling palms (to 1 ft) have survived lows from 29 to 27f (Orlando) w/ some foliage damage. PRITCHARDIA sps. : all species recorded moderate to severe foliage damage at temps from 29f to 26f (Orlando). P.beccariana is recorded as surviving 25f (Daytona). P.thurstonii and P.pacifica were killed by 23f (Vero), P.affinis killed by 22f (Daytona). PSEUDOPHOENIX sargentii (6 ft to 2 ft): killed by 19f low (Melbourne); survived 25f low (Daytona) basically undamaged. During the same freeze another specimen was killed, some variability does exist; perhaps the Florida strain (P.sargentii sub-species sargentii) does possess more cold hardiness than the others from the Caribbean (sub-species saonae or saonae var. navassana). The sub-species sargentii was undamaged @ lows from 29 to 26f (Orlando). PSEUDOPHOENIX vinifera (5 ft): killed @ 25f (Daytona) PTYCHOSPERMA elegans (10 ft to 5 ft): killed @ 25f (Orlando); defoliated @ 29f (Orlando) PTYCHOSPERMA macarthurii (4 ft) defoliated @ 22f (Daytona) but re-grew from the roots. RAPHIA farinifera (9 ft to 3 ft): defoliated by recovered from 22f (Daytona) RAVENEA rivularis (9 ft to 6 ft): basically undamaged @ 29-28f (Orlando, shaded) and severe damage @ 27-26f; defoliated but recovered from 23f (Orl., shaded location). Most specimens have died from exposure to temps in the 27-23f range, not reliably hardy for interior central Fla. RAVENEA xerophylla (1 ft): undamaged by 29-26f (Orlando) RHAPIS sps. (6 ft to 2 ft): excelsa and humilis were moderately damaged by 22f (Indian Harbour) but recovered nicely. Both palms were undamaged @ 29 to 26f (Orlando). R.subtilis was killed @ 23f (Orl.) ROYSTONEA oleracea (5 ft to 3 ft): were killed by 25f (Daytona); a 4 ft. palm was undamaged @ 29f (protected) in Orlando ROYSTONEA regia (formerly elata): tall mature palms were killed by temps from 19f (Orl.) to 22f (Day.). However a scant few specimens did survive the 23-22f lows along the Brevard county coast, albeit totally defoliated and some w/ severe stem damage, showing to this day. This palm seems to increase in hardiness as it ages, smaller palms (under 6 ft) are severely damaged if not killed by lows in the high 20s. Once past this size they can take & recover from one time exposures to temps as low as 27-26f (Orl.). SABAL sps : the native species (etonia, minor and palmetto) are obviously suitable for our area. The following group - causiarum, domingensis, bermudana, mexicana, rosei and uresana, were recorded as undamaged at temps ranging from 18f (S.causiarum in Gainesville) to 19f (S.domingensis, Orlando) to 22f (S.bermudana, S.mexicana and S.rosei, Daytona). S.uresana was undamaged @ 25f (Sebring) and most likely can tolerate much lower readings. There are two Caribbean species (S.mauritiiformis and S.yapa) and though not as hardy as the others they have been cultivated to mature status throughout most all of central Fla. Both species seem about equal in hardiness showing foliage damage around 26f (Orl.); mauritiiformis was defoliated @ 22f (Day.) and yapa was severely damaged @ 19f (Mel.) but without total defoliation. SATAKENTIA liukiuensis (6 ft to 3 ft): killed @ 23f (Orlando); basically undamaged @ 29f (Orl.) but foliage burn appears @ 28 to 26f (Orl.) SCHIPPIA concolor (2 ft): basically undamaged at temps ranging 28 to 26f (Orlando); only moderate damage @ 23f (Orl.); killed by 19f low (Melbourne) SYAGRUS romanzoffiana: some tall mature palms were killed by 19f lows (Orlando and most of interior cen. Fla.) but there were also many survivors, some right next to specimens that were dead. The specimens receiving proper care were most likely to survive the extreme cold. Pre-flowering juveniles (12 ft to 8 ft) were unaffected by a one time 23f low (Orl.). Other SYAGRUS sps. : S.amara, S.coronata and S.sancona were killed by 22f low (Daytona); S.flexuosa survived that same 22f low; amara, coronata and sancona were severely damaged but did recover from 25f low (Day.). All 3 species show slight foliage burn @ 28f (Orlando). S.schizophylla was killed @ 23f (Orl.) but survived a 22f (Day.) w/ total defoliation. Palm was killed by 25f low a few years later. S.oleracea was defoliated but survived 19f low (Melbourne). Judging from the data it would seem that oleracea and flexuosa would be next in line to romanzoffiana in terms of cold hardiness. The others can be tried along the coastal areas w/ some hope for long term success. There are several acaulescent species (vagans, smithii) just now coming into cultivation that hold great promise. Other tree Syagrus (botryophora, cearensis) have been recently planted out. THRINAX morrisii (10 ft to 5 ft): killed @ 22f (Daytona) but some specimens survived 19f (Melbourne); undamaged @ 26f (Orlando). Despite a more southerly habitat this species has been proven more cold tolerant than its mainland Fla. native cousin, T.radiata THRINAX radiata : mature palms (over 10 ft) were killed by 22f (Indian Harbour) as well as 19f (Melbourne). Foliage damage appears at 28-26f (Orlando) and severe damage/total defoliation results from anything slightly lower. Thrinax parviflora shows damage @ 28-26f (Orl.), probably is no hardier than radiata. A small Thrinax excelsa was undamaged by a one time 29f low (Orl.) TRACHYCARPUS fortunei : undamaged at temps as low as 18f . Cold is not a problem but this palm genus as a whole is difficult to establish in wet humid areas. Inland cen. Fla. may the extent of its southerly range, a palm more suited to north Fla. and farther up. Trachycarpus martianus survived 22f low (Daytona). A species new to cultivation (T.latisectus) has been reported to be a good possibility for humid locales such as ours. TRITHRINAX sps. : T.brasiliensis (a.k.a. acanthocoma) survived 19f low (Melbourne) undamaged. Once again another palm tolerant of our worst cold but is difficult to establish in warm, humid locales. Avoid overhead irrigation on any sized palm (extremely prone to bud rot at any stage). Trithrinax campestris is possibly even more cold hardy than brasiliensis; no problems w/ 19f low (Tampa area). Again difficult to establish in warm, humid locales. VEITCHIA sps. (6 ft to 3 ft): three species (joannis, montgomeryana, winin) all show damage @ 29-28f lows (Orlando, Daytona). Severe damage and even death can occur at anything lower. Not recommended for any part of inland cen. Fla., only protected coastal locations. All species killed by lows ranging from 25 to 22f. WALLICHIA sps. : two species, the small, clustering W.densiflora and the solitary W.disticha were undamaged @ 29-28f lows (Orlando). A 4 foot disticha was killed by 22f low (Daytona). WASHINGTONIA filifera: tall mature palms easily survived 19f lows (Tampa area, Mt. Dora/Leesburg). The cold is not a problem as much as the consistently moist, humid summers which initiate persistent fungi problems on the foliage. Slight foliage burn appears at temps below 20f. WASHINGTONIA robusta: tall mature palms were severely damaged @ 18f low (Umatilla) and killed @ 15f low (Sorrento). More tolerant of our humid summers; prone to death via lightning strike once the palm stands above surrounding vegetation. WODYETIA bifurcata (10 ft to 4 ft): small palms (under 6 ft) killed by 23f low (Orlando). Slightly larger palms survived same freeze albeit totally defoliated. Foliage burn appears around 28-27f (Orl.). Not present during the great 1989 freeze, most likely would not have survived 19f lows. ZOMBIA antillarum: large clump completely killed by 22f low (Daytona) but as a clumping palm it re-grew from the roots after a 23f low (Vero). Undamaged by 29-28f lows (Orlando), anything lower will result in severe foliage damage. WINTERIZING PALMS ??? reprinted from The Palmateer, Dec. 2000 For the past two winters I have been experimenting a bit with various combinations of fertilizers in an effort to pump up the salt volume inside of the palms cells, thus increase the cold tolerance of certain marginal species. The theory being that salt water takes longer to freeze than unsalted water and that this should decrease the chances of the palm cells exploding due to crystallizing from water expanding inside of them. This idea is certainly not an original thought on my part. The first time I had come across it was from a suggestion made via the Internet a few years ago by Henry Donselman. Also here in Florida most all of the golf course greenskeepers spray a solution of liquid urea on the turf just before any freeze is forecast. For the most part these experiments seemed to be successful with a few caveats. Keep in mind the cold my palms were subjected to were two separate one-time exposures but nevertheless the passing fronts provided enough cold for a long enough time to severely damage some of the same specimens in similar conditions/freezes previous to these tests. 1998 - 1999 RESULTS 1/5/99 - The temperature reached 32F approximately 12 a.m., 30F by 4 a.m., 28F by 7 a.m., then hit 33 at 8:30 am. Time below freezing approximately 8 hours. A 5 M.P.H. wind kept the frost away until around 4 a.m. It began forming on lower leafs & grass shortly thereafter. UNDAMAGED PALMS - that possibly could or in the past did suffer some damage Aiphanes aculeata - 3 ft. was damaged by slightest frost & lower temps in 2 previous winters Archontophoenix alexandrae - 4 ft. others of this species were always fried by any frost but this latest addition was sheltered under an oak Arenga pinnata - 6 ft. previous planting of nearly equal size was killed by similar cold Chamaedorea cataractarum - 4 ft.- planted next to house Chamaedorea glaucifolia - 1.5 ft. planted under an oak Chamaedorea metallica - 2.5 ft. planted next to house Chamaedorea stolonifera - 3.5 ft. planted next to house Copernicia gigas - sdlg. new planting should be susceptible to cold Copernicia glabrescens - sdlg. - new planting should be susceptible to cold Copernicia yarey, sdlg. - surrounded by frost damaged grass yet no damage Cryosophila stauracantha - 2 ft. previously showed damage by similar cold Dypsis decaryi - 14 ft. previously showed damage by similar cold Gaussia maya - 5.5 ft. nearly 50% burned by similar cold Kerriodoxa elegans - 1 ft. nearly 50% burned by similar cold Licuala spinosa - 1.5 ft. - nearly 50% burned by similar cold Medemia argun - 1.5 ft. cold hardiness basically unknown ??? Pseudophoenix sargentii - 4 ft. and 1 ft. slightly damaged by similar cold Ravenea rivularis - 6 ft. - slightly damaged by similar cold Ravenea xerophylla - sdlg. - cold hardiness basically unknown ??? Roystonea regia, 10 ft. - nearly 50% burned by similar cold Sabal mauritiiformis - 5.5 ft. - slightly damaged by similar cold Sabal yapa (dwarf form) - 2.5 ft. - slightly damaged by similar cold Schippia concolor - 3 ft. - slightly damaged by similar cold Syagrus amara - 6.5 ft. - slightly damaged by similar cold Syagrus sancona - 6 ft. newer planting, possibility of suitable cold-hardiness may exist Thrinax morrisii - 2 palms over 3 ft. were undamaged by previous freezes w/ lower temps Wodyetia bifurcata - 8.5 ft. - nearly 50% burned by similar cold DAMAGED PALMS - APPROX. HGT. - NOTES Attalea butyracea - 2.5 ft. - about 25% foliage damage @ worst; mostly lower leafs Attalea speciosa - 2 plants w/ 2 leafs each; minor (less than 25% burn) Caryota mitis - 9.5 ft. - foliage burn less than 50%; confined mostly to upper, exposed leafs but newest opened fronds (two since Dec.) were undamaged Chambeyronia macrocarpa - 3 ft.- less than 25% damage; confined to lower 2 leafs (out of 4) Corypha utan - 6.5 ft. - at least 75% damaged; all leafs show burn except latest 2 (no damage) Dypsis leptocheilos - 4.5 ft. - some spotting to nearly all leafs, foliage burn less than 25% Elaeis guineensis - 7 ft. - a few leaf spots on most older fronds, new ones okay; no burn marks Hyophorbe verschaffeltii - 9 ft. - foliage burn close to 50%; confined to oldest fronds only Hyophorbe hybrid (bottle/spindle cross) - 2 ft. - no burn marks but cold spots on all 3 leafs Roystonea oleracea - 3.5 ft. - foliage burn on 2 oldest leafs (less than 50%); spotting on new one Syagrus coronata - 3 ft. - about 50% burn to exposed oldest leafs, 2 newest ones are okay Syagrus X costae - 12 ft. - 50% at worst to most fronds; newest leafs okay Thrinax parviflora - 3 ft. - about 50% at worst to all 3 fronds Thrinax radiata - 3 ft. - very minor burn (less than 25%) to most fronds; newest 2 okay Zombia antillarum - 2 ft. - planted under Bismarckia, very minor (10%) burn marks & spots I fertilized all of the above plantings in mid November with a basic landscape fertilizer, a 17-3-11 polymer coated formula from Lesco. I also added in a 0-0-60 (straight potassium) to the mix in equal amounts. I followed the normal application rate for palms. During the month of December we had above average temperatures as well as an adequate supply of rain. Lots of my palms slowed down but continued to grow. At the time of the cold front that blew through (I had mid 30F for a low the day before the freeze) several palms were just beginning to open new fronds. These palms were: Bismarckia, D.decaryi, S.costae, R.regia, C.mitis, R.rivularis, L.mariae, A.totai, C.prunifera, C.argentata, T.morrissii, E.guieensis, A.engleri, C.baileyana and A.arenaria. All of these fronds are completely undamaged. A few of these I knew would be fine but the Ravenea, Elaeis, and the Syagrus hybrid are a bit surprising, especially since the Syagrus hybrid was one of the most damaged palms in previous freezes of similar duration and temperature. I truly believe the palms ability to withstand the cold (and accompanying frost) was increased by fertilizing. I believe this because in 12/95 a 29F freeze had far more effect on my palms than this one did. Also a freeze in January 1996 w/ a low 27F and 5 hours below freezing did much more damage than this latest one. 1999 - 2000 RESULTS 1/27/00 - Reached 32F degrees approx. 5:30 a.m., was back at 32F around 7:30 a.m. The low was under 30F, but not quite 29F. This was the 2nd day of a passing cold front; the previous nights low reading was about 33-34F. Weather forecasts had predicted the 2nd night to be warmer than the previous night. DAMAGED PALMS Satakentia liukiuensis - 3 to 4 ft. overall, badly scorched but never looked too good anyway Actinorhytis calapparia - was 8 ft overall, now maybe 7 but it has always come back NOTE: both palms have since died this following summer; this is the 2nd trial run for each species, neither of which appears to be a good subject for areas where freezing temperatures are an annual occurrence. While they manage to survive light freezes, each year they go into the next winter with less & less foliage, regressing to the point where they cannot make it another season. Roystonea regia - 12 ft; well in excess of 50% green, probably closer to 75% Syagrus X costae (hybrid) - some spotting but only on the fronds that reached over the roof Elaeis - 10 ft; very minor spotting and some yellowing on a few fronds Syagrus amara, 7.5 ft. seemed fine at the time but shortly some yellowing/spotting appeared Caryota mitis, approx.15 ft.; minor spotting, if anything - this is a first !!! Chambeyronia - 3 ft. overall, a few spots on all the fronds Hyophorbe verschaffeltii, approx. 10 ft. all fronds almost completely burned on the adaxial (upper sides) of the fronds while the abaxial (lower) sides were almost completely undamaged ! Corypha utan - approx.8 ft. newest 3 fronds showed severe burn, most all of the older foliage was either undamaged or showed minor spotting/yellowing typical of this genus in cooler weather. There are several important factors to consider regarding the above list of damaged palms. Although this freeze was less severe overall than in 1999 it was nevertheless a true radiational freeze, the 2nd day of a passing cold front. The 1st day the lows reached to 33-34F, the 2nd day there was no cloud cover to trap heat accumulated during the day and no wind to keep the frost at bay during the night. Therefore the frost was able to form quickly and early on most all exposed vegetation in the vicinity. The frost alone is usually a death knell for the exposed palm foliage of the following species but this time around some pleasantly surprising results were in store: Caryota mitis, this specimen was frozen to the ground from the winter of 95-96 and although suffering some damage each successive winter, this time around the palm was well in excess of 90% green. Normally this palm shows cold damage if the refrigerator door is left open too long. It is also planted in an open, unprotected spot on the NW corner of the house (right into the teeth of any oncoming cold front). For the past two winters it was not defoliated, the only two occasions this has ever happened out of six winters. The only change in routine from previous years is the fertilization application in mid November. Corypha utan, another species that was/is basically defoliated on an annual basis until mid November fertilizing. This palm had suffered severe damage and/or total defoliation at the slightest frost and for the past two winters it was heavily damaged in each but managed to keep 3 to 4 healthy green fronds each time. Anyone growing this species outside of a tropical locale should be aware of the significance of any remaining, healthy foliage. This small amount of foliage has been more than enough to sustain it through the remaining cold days and once the temperatures rise it grows quick enough to completely recover and develop a full crown of leafs before Summers end, unlike the aforementioned Satakentia and Actinorhytis palms. Roystonea regia, past experiments w/ palms under 8 ft. overall all ended in failure (= dead palm) so I decided to go to a bigger is better approach. I planted a 10 ft. specimen in a full sun location during early Spring 1998 and the result from the past two winters is once again decidedly more positive than anything previously recorded here. The palms size may have played a part in this but nevertheless it was covered w/ frost by daybreak. Past trials had resulted in near or total defoliation when this occurs but not this time (approx. 65-75% green overall). Syagrus X costae, this hybrid of coronata and oleracea was planted as a large (over 10-ft.) specimen in Spring 1996. It has been severely damaged although never defoliated, during each subsequent winter. This palm is planted next to the south facing wall with no canopy and adjacent to the aforementioned Roystonea. After the winter of 98-99 the palm was well over 50% green, the best it had ever fared until 99-00 when the only damage was to the outer edges (tips) of several (but not all) fronds. Palms that basically suffered the same damage as always despite fertilization: Elaeis guineensis, this one showed latent cold damage. It seemed just fine for about one week but as time passed I noticed several faded areas or scorched marks on each frond but mainly the oldest. Each frond including the most damaged were 90% green at worst. Hyophorbe verschaffeltii, time exposed to frost was the main culprit here; no frost formed on the lower sides of each frond so no damage there, only to the more exposed upper sides. Syagrus amara, another that exhibited latent cold damage with the same results as the Elaeis. Both palms are planted next to each other in an open area. Several smaller species (under 3 ft. overall) - Attalea butyracea, Thrinax parviflora, Thrinax radiata and Zombia antillarum were undamaged through the winter of 99-00 but damaged during the previous winter of 98-99. Each palm (except the Zombia) is planted in an open unprotected area. All four species are widely considered to be tender to any frost or freezing temperatures. I would attribute the undamaged Zombia from being planted underneath a Bismarckia palm but the remaining three I would consider as being yet another testament to the additional late season fertilizing. Final notes: I choose the time frame of mid November for these applications because it takes a minimum of two weeks if not slightly longer for the granular fertilizer to initiate being absorbed by the palms. In the past most tests have indicated that palms generally stop feeding or lose the ability to process fertilizer once the mean temperature drops below 60F. Considering my location (Orlando, Fl.), I felt the time of application would be sufficient in case of an early cold front, (which if history is any indication are always among the worst). For this coming winter of 2000-01 I plan to continue these trials with granular products as well as applying some liquid mixtures to smaller palms and newer plantings a day or so before any freeze is forecast. As to the products themselves, I think the important idea is to fertilize without much regard to the brand or type of product applied (but preferably with something that can release slowly over the course of winter). Future tests may or may not reveal some variances caused by using different ratios or products. But the gist of this is to get some salt moving through the plants system before the worst cold arrives, and if it does not arrive? Then you have a healthy, well-fertilized plant anyway. In the past our newsletter has published information from the University of Florida regarding the proper ratios for fertilizing cultivated palms in Florida. Their suggestions were, on a regular basis to increase the potassium levels to as much as if not twice the number of the nitrogen level. This recommendation was made mainly due to this mineral (K) quickly leaching through our sandy soils. Potassium is also well known to amplify a plants ability to withstand stressful conditions including drought. I would suggest applying some extra K as a protective additive along with the regular granular fertilizer. Until next winter... 3 Link to comment Share on other sites More sharing options...
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