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Mound planting of Sabal spp. How tall should mound be?

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Phoenikakias

In a particular spot of my garden I face great problems to grow successfully any Sabal sp. In all cases ( and they are not few, more than six) any out planted Sabal starts rotting in the below soil level lying part, that is the bulb, and in particular from inside outwards. Roots remain however healthy even after plant's death. Therefore I have decided to mound plant next Sabal candidates for this spot, filling the mound exclusively with pumice. Any idea how tall should be the mound for Sabal plants? 

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OC2Texaspalmlvr

Im interested in knowing were these Sabal sp. all trunking form ? What is the soil like in this particular area of the garden ? I have seen many pics here on PT of S.minor sp. growing in almost swamp like conditions. What size palms are you planting ? 

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Phoenikakias
4 hours ago, OC2Texaspalmlvr said:

Im interested in knowing were these Sabal sp. all trunking form ? What is the soil like in this particular area of the garden ? I have seen many pics here on PT of S.minor sp. growing in almost swamp like conditions. What size palms are you planting ? 

Check following links. They lead to relevant topics in present forum.

https://www.palmtalk.org/forum/index.php?/topic/59077-whats-wrong-with-my-sabal-etonia/&tab=comments#comment-879954

https://www.palmtalk.org/forum/index.php?/topic/60662-sabal-disease/&tab=comments#comment-898858

https://www.palmtalk.org/forum/index.php?/topic/55541-ssds-help/&tab=comments#comment-832355

Soil is mainly clay with a lot of rocks. Actually this spot had been elevated up to more than 9' by the help of a retaining wall and practically serves as a huge mound. But obviously this is not enough.

Edited by Phoenikakias

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Phoenikakias

This summer I have replaced a good amount of native clay soil with one rich in organics and sand

20190707_100500.thumb.jpg.b6f5bbbc75c6046615322a1edbd3563b.jpg

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Phoenikakias

20190707_110013.thumb.jpg.f88896b6934b9a96a4518e6b9f96a377.jpg

Left new soil, right old soil

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Phoenikakias

20190707_100529.thumb.jpg.5e2d7c474d44ecd1e239ef2484a9d515.jpg

Old soil

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Phoenikakias

20190707_100516.thumb.jpg.e3737f581ba0d781d0dca50978766196.jpg

New soil. I still do not feel safe enough without an additional mound around each plant.

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OC2Texaspalmlvr

Going back to those links , now i mber your dilemma. So SSD ? What causes it not sure if that was ever explained or still an unknown =/ Chances are your prolly gonna be the one to figure it out thru trial and error. By chance have you grown any Sabal sp. In pots in the same locale if so any different results ? Im sorry i couldnt be more help as im learning alot of things on the fly myself. Tho PT is a wonderful place to learn from others mistakes. I wish your future Sabals better luck. It doesnt look like youll be giving up on this genus anytime soon. 

TJ 

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Phoenikakias

Yes, I have been growing Sabal specimens in pots quite often. Never faced such problem.  What is your opinion on the height of future mound?

Edited by Phoenikakias

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OC2Texaspalmlvr

To make an educated guess on mound height , it really depends on what your trying to get the roots away from ?  Your other threads it didnt seem like root rot correct ? Which is usually the biggest reason you mound  up , cause of bad drainage which you had with your old clay soil. Since you have amended the area , hopefully you will have much better drainage now. If you just really want to mound just to be on the safe side i would go maybe 6" over grade. The size of palm planted i think would really determine height for aesthetics. 

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kinzyjr
22 hours ago, OC2Texaspalmlvr said:

Im interested in knowing were these Sabal sp. all trunking form ? What is the soil like in this particular area of the garden ? I have seen many pics here on PT of S.minor sp. growing in almost swamp like conditions. What size palms are you planting ? 

While reading this thread, the part in bold stuck out the most to me.  It's hard to believe that a Sabal minor, palmetto, or etonia would have much issues with moisture in a Mediterranean climate.  At Highland Hammock in Sebring or out at the Circle B ranch here in Lakeland, palmetto and minor literally grow in shallow standing water in the swamps.  SSD may be a variant of Lethal Yellowing/Lethal Bronzing judging by the symptoms.

As far as the mounds go, it is usually determined by the radius of the mound.   You usually want an inch of drop for every foot of radius in a circular mound as a general guideline.

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NOT A TA

I agree with kinzyjr that it's probably not due to too much water, if anything perhaps too little water. Palmettos and minors live in sand on the edge of water here so the root systems are pretty much under water. A garden at the top of a retaining wall like that will require a lot regular water due to the surface area of the wall drying out the soil. It appears that the fence is on a concrete wall. The wall will act like a sponge pulling moisture out of the soil behind the wall and evaporating it unless there was a vapor barrier put on the inside of the wall. 

I doubt mounding will be beneficial (and may make the problem worse) though replacing the soil may help although possibly only temporarily (if there's chemical soil contamination afterward).  Having seen the other threads mentioned in the past and the symptoms described I'd think lack of water or a chemical could be causing the problem. Cats aren't likely to be the problem. The mention that the plants were in place for a long time prior to dying leads me to think something changed in their environment unless there's a disease in your area. Any neighbors have similar plants?

Is there an irrigation system?

How long has the patio been in place?

How is the patio cleaned? Power wash? Scrub brush?

Are any weed killers used on the patio area?

Does anyone take things out on the patio to wash or use any type of chemicals on patio for other reasons?

Are the rabbit screens & pipes galvanized metal? Are they getting old and the galvanic coating coming off?

Does the plant decline occur at a certain time of year where rainfall is high? Does runoff from the home roof get to the plants?

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BS Man about Palms

As one of the originators of "mound planting" as such, I'll chime in...lol.  There are several factors that come into play here. Obviously in habitat, Palms don't mound plant themselves, it is generally taking a plant native to an area and trying to grow it in often very disparate environments.

So Cal is a "Mediterranean" environment too,  characterized by low rainfall amounts and long cool winters. Throw clay in the mix and it is difficult for some Palms to thrive until established. When your winters average months of nighttime temps in the 40's and daytime highs rarely reaching 75, it is difficult for a "tropical" plant to survive. So the mound planting was an attempt to help a bit. Generally the water supply has a high salt level as you do not have rainfall to depend on. (At least in So Cal, our water comes from a long ways away. ) Throw in clay that retains water very well and drains poorly and there is your recipe!

The idea is to mound plant heeled palms as they often have slow root growth and tend to burrow a bit before gaining vertical height. By mound planting, if you have excessive water and a cool winter, then a large part of the roots and growing point is above the wet cold clay/soil. it can shed off. Once a palm "needs" that moisture, dropping the roots abit will get all it needs. Until then, extra water on your behalf if warm will keep the palm happy.

All that being said, as a general rule for myself, any palm I choose to mound plant, "half the pot height" is what I go by.

Good luck!

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Phoenikakias
15 hours ago, NOT A TA said:

I agree with kinzyjr that it's probably not due to too much water, if anything perhaps too little water. Palmettos and minors live in sand on the edge of water here so the root systems are pretty much under water. A garden at the top of a retaining wall like that will require a lot regular water due to the surface area of the wall drying out the soil. It appears that the fence is on a concrete wall. The wall will act like a sponge pulling moisture out of the soil behind the wall and evaporating it unless there was a vapor barrier put on the inside of the wall. 

I doubt mounding will be beneficial (and may make the problem worse) though replacing the soil may help although possibly only temporarily (if there's chemical soil contamination afterward).  Having seen the other threads mentioned in the past and the symptoms described I'd think lack of water or a chemical could be causing the problem. Cats aren't likely to be the problem. The mention that the plants were in place for a long time prior to dying leads me to think something changed in their environment unless there's a disease in your area. Any neighbors have similar plants?

Is there an irrigation system?

How long has the patio been in place?

How is the patio cleaned? Power wash? Scrub brush?

Are any weed killers used on the patio area?

Does anyone take things out on the patio to wash or use any type of chemicals on patio for other reasons?

Are the rabbit screens & pipes galvanized metal? Are they getting old and the galvanic coating coming off?

Does the plant decline occur at a certain time of year where rainfall is high? Does runoff from the home roof get to the plants?

Ok many questions, but all well put! I will try to answer all. Irrigation system does exist and is a drip one, which is set to to turn on daily during summer, plus a good watering with the hose once weekly during same season.

Patio has been in place for over 35 years, that is before the existence of any palm there

Patio gets never cleaned. 

Never apply a weed killer, but only once maybe 7 years ago. And then it was rather an a application with paint brush of 'crossbow' on stumps of olive trees and some offshoot of latter, in order to get rid of them permanently. Thing is that such treated olive tree stumps are scattered along the whole strip of earth in this part of the garden, but I am confronted with the problem only in the central section. There are other Sabal specimens growing still near old olive tree stumps, like causiarum, rosei, uresana and mauritiiformis and they thrive.

No galvanized metal.

There is definitely a consistent relation to a certain season and this is late summer to early autumn. All affected specimens, all without exception, had entered active growth season of the same  year of their demise in complete health and with great stamina.  Then after some good growth during spring and 2/3 of summer time, they had stopped abruptly any further growth and shortly after it the decline had started. Run off from home roof does end indeed to this strip of earth, but mainly, the largest quantity of it, on the left margin, where a Sabal uresana juvenile thrives.

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Generally speaking, rain occurs only during winter and precipitation is very low even compared to mediterranean standards. Soil gets reliably moistened during winter rather through condensed maritime air moisture. Coincidently the pit for this Sabal uresana had been half filled in with pumice during ground planting, becauce I had run out of any other suitable medium. Remarkably also the other end of same earth strip, where the rest three aforementioned Sabal specimens thrive, consists for some reason of comparatively lighter native soil. Soil is more compacted in the center (but even much more so in the left end around the spot of Sabal uresana). 

What you have certainly overseen, is the fact that I am bound to spray with pesticide once per every summer month all palms in my garden, in order to protect them from some newly invaded, nasty borers (rpw and Paysandisia archon). This practice combined with the habit of this genus to bury initially deeply below ground its growing point, further combined with increased watering and with soil compaction, makes bulb vulnerable to fungal infection. This is my assessment and I hope it is correct because imo lethal bronzing or yellowing are far more serious threats for the rest of my palms.

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NOT A TA
7 hours ago, Phoenikakias said:

There is definitely a consistent relation to a certain season and this is late summer to early autumn.

Is that a very low rainfall or particularly windy time of year?

Is there by any chance a wall of windows that the sun would reflect off of to the area at that time of year?

Did you change the time of summer to apply the pesticide to see if it made any difference?

Is there a possibility of buying very small specimens of the varieties you want to use and testing the pesticide on them while in pots?

The cool wet winter with clay situation BS Man about Palms discussed seems like a place where mounding at the time of planting is beneficial. Your plants were also in a clay soil but as you mentioned.....

8 hours ago, Phoenikakias said:

All affected specimens, all without exception, had entered active growth season of the same  year of their demise in complete health and with great stamina.

The plants were healthy before sudden demise, at the same time of year, in repeated cases, which leads me to look for a simple environmental cause. All of my questions are to perhaps make you look at something you may have overlooked.

When I ran nursery's that did planting installations and landscape construction companies we guaranteed all the plants we installed on landscaping jobs for a full year. For big commercial jobs we'd take care of watering & bill accordingly as part of the contract. On smaller jobs if a plant or several died there was usually a human related reason. The most common was just lack of water. In that case we'd show the customer how dry the soil around the root ball was by pulling up the plant(s). It takes a lot of water to soak soil down to where the roots are trying to establish. Then I'd have to diplomatically explain that they weren't going to get free plants with free installation because it was their fault the plants died. So I'd figure out costs so the company wouldn't lose money replacing the plants and the customer wouldn't pay normal full price. I'd also note that the one year guarantee would restart on the replacement plants.

A simple experiment shows how large a volume of water is required to soak the soil. 

Pick an area such as your strip and before planting level the soil and compact it a bit as you would before installing mulch. Fill a 5 gallon ( or metric equivalent) bucket with water and slowly pour it onto the area and let it soak in a bit. Dig straight down right in the middle of where you poured with a shovel and see how far the water soaked in. It won't be very deep so fill the hole back & compact refill the the bucket & repeat pouring the water in the same place, wait then dig. Then continue repeating the process several times and you'll see it takes a LOT of water and you'll probably quit before getting to root ball depth. Think about how long you normally hand water and how long it took to fill all the buckets. This is why it's so important to fill the hole with water when new plantings are done, without doing that most people don't water enough to dampen the soil more than a couple inches and the plant dies of thirst in a relatively short time even though people say they've been watering.

Thick mulch often exaggerates the problem because the mulch absorbs a lot of water before it even gets to the top of the soil then often it evaporates from the mulch before the next watering so the soil doesn't get any water never mind the roots down deep. While mulch is good at moderating soil temperature fluctuations and evaporation from the soil it also adds to the volume of water required overall. People are often surprised if I tell them to brush away some mulch after they've watered and examine the area to see how little water actually even reached the top of the soil. Often the mulch isn't even soaked through.

 

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The Steve

I’ve planted a number of Sabals in my Mediterranean climate.  I’ve never mound planted one, and they grow fine in out rocky/clay base soil.   I’ve overwatered Sabals in pots, but this becomes more difficult as they get a bigger rootball, and suck up that water.  I suspect that mound planting can be beneficial in certain situations, but I’m not sure that it’s necessary in your case.  My neighborhood was built in a mesa, and is 350’ above sea level, at 4-5 miles from the bay.  I know that you live in a little different climate, but I expect that there are probably a few similarities. I do get occasional pests on one of them, but it grows too fast to be seriously affected.   I suspect that the pests are related to the lack of water, since they only get occasional drinks from the big orange bucket, that I carry over.  They all have mulch.  I’ll try to get some pictures later.  I love your stone pathways.  

Edited by The Steve

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The Steve

Bermudana/Uresana/Maritima

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