Pine bark mulching for Cycas media?

[Phoenikakias]

I grow in the same position three Cycas spss, two from China (guizhouensis and panzhihuaensis) and one from Australia (media). They all grow in a very porous medium consisting primarily of gravel and pumice. While all three are healthy looking, only the chinese cycads have been producing leaves every year and the media had stopped showing any growth since several years, though it has kept a healthy caudex. Having followed this summer the advice of an american cycad fan I applied around the media pine bark as mulch and presto, 5 brand new leaves have almost fully developed! The paradox is however that same mulch proved fairly detrimental for some palms (Sabal and Pritchardia spss). Are there known other Cycads, which can profit from this mulch?

[Kostas]

I have my whole garden mulched with pine bark(and whatever my plants throw) and don't get any rot problems from it. I mulch shallowly around palms though,just 2-5cm are fine depending on palm species and mainly its size. A few wet loving palms have it more thickly and I also have some cycads with underground stems growing under quite a lot of mulch happily. I would say not all species are the same nor like the same conditions,but if the medium they are growing in is correct and the watering schedule is correct and according to the species individual needs,then mulch shouldn't be detrimental to any species if applied correctly. I even mulch my Encephalartos and they like it!

One thing to watch out for though is that pine bark mulch can get real hot in full sun and certain cycads can get their petioles burnt where they touch the mulch if they get sun in summer and don't cast enough shade yet themselves. In that case,throwing dead leafs over the pine bark mulch around the cycad,where the petioles emerge from the ground,solves the problem as leafs and especially light colored ones,don't get burning hot like pine bark does.

[Phoenikakias]

I do not know what chemical reaction took place in my soil, but fact is fact that all my Sabal suffered from the pine bark layer, they hardly promoted any growth this year and most concerning has been that old leaves lost their cardboard texture (very useful in my windy area)and emerging spear started unfolding prematurely and had a very loose look. My humble experience has warned me of lethal decline start! As far as I removed pine bark together with the addition of some Plocher dolomite same plants regained their previous hard texture and pushed another spear next to the still loose one.Same negative experience (but in last case premature yellowing of older leaves) I had also with a Pritchardia planted in a pumice based substrate with also same recovery. Those are facts and I am not in the position to give an explanation, which Anyway is not of practical significance, it suffices that it has happened!

[Kostas]

I dont question your facts,just sharing my experience with pine bark mulch which i have been using for some years now with noted better results overall and obvious soil building in this time! My mulched Sabal grow fine as well as my Pritchardia. Haven't had any of those through a winter yet though but mulch is something palms would have in habitat and especially palms of these two genera. What may have caused your problems is frequent hand watering along with mulch. Mulch keeps things moist longer so usually you need to water less often after mulching. Also,when I water my palms once every 3 days(in summer) with drip irrigation,their crowns aren't wet,only the soil under the mulch is. With hand watering the crown is easily wet in the process and mulch keeps things under it humid and wet for longer,including the wet leaf bases and growing point under it,so I can see how problems can arise with everyday hand watering of mulched plants. With mulch however,you can water less often and avoid such problems. Rain usually doesn't cause rot problems. If you want to be extra cautious,you can use a single or double layer of mulch pieces over the soil next to your plants and only use very course pieces around your plants.

[Kailua_Krish]

It must be something with your soil, Sabals are mulched extremely heavily with pine bark (it is the predominant mulch in much of the SE USA) and they usually grow quite well with it. In fact I would mulch my entire garden with pine bark if it werent so expensive, right now I just use it in highly visible areas and mulch with oak leaves in the rest.

[Phoenikakias]

I dont question your facts,just sharing my experience with pine bark mulch which i have been using for some years now with noted better results overall and obvious soil building in this time! My mulched Sabal grow fine as well as my Pritchardia. Haven't had any of those through a winter yet though but mulch is something palms would have in habitat and especially palms of these two genera. What may have caused your problems is frequent hand watering along with mulch. Mulch keeps things moist longer so usually you need to water less often after mulching. Also,when I water my palms once every 3 days(in summer) with drip irrigation,their crowns aren't wet,only the soil under the mulch is. With hand watering the crown is easily wet in the process and mulch keeps things under it humid and wet for longer,including the wet leaf bases and growing point under it,so I can see how problems can arise with everyday hand watering of mulched plants. With mulch however,you can water less often and avoid such problems. Rain usually doesn't cause rot problems. If you want to be extra cautious,you can use a single or double layer of mulch pieces over the soil next to your plants and only use very course pieces around your plants.

Kostas, I sincerely appreciate your effort to explain failure, but given explanation does not match the whole picture. Last year I applied as mulch commercial compost from seaweed (black in color that gets hot in summer sun) and same plants responded so well beyond any expectation. Especially regarding the Pritchardia pine bark mulch was very sparse and away from trunk, nonetheless its growth with mulch has been also troublesome and its recovery after removal has been equally spectacular Another Pritchardia nearby without this mulch fared much better .Besides this part of garden lies 4 meters higher above natural soil level (supported by concrete wall) so there are no issues with drainage (even after the strongest rainfall during winter I have never observed stagnant water). Additionaly in the same lot used to grow for decades olive trees, which have been cut down but their root system has already created underground tunnels, so also a compaction issue is excluded. Therefore if I reduce watering two days weekly and only through dripping palms are condemned to desiccation. Krishna another grower from Florida avoids using pine bark as mulch because it is to oily. I am convinced that in this particular part of the garden a chemical reaction because of the pine bark was in process.

[Kostas]

Who really knows what they didn't like,just trying to give ideas but since you do have been using mulch,you probably know the problems I mentioned.

Pine bark isnt oily in general,doesnt give me any such sense,at least the ones i have been using. Maybe when heated a lot from the sun you can get a slight oily feeling but nothing worth mentioning. And after some rains,it starts absorbing water well and fast,aiding in its breakdown.

Wish your palms fast and good growth!

[rprimbs]

In my experience Australian cycads tend to favor an acidic soil and fertilizer. I don't know if all cycads do, or even all palms.

[Phoenikakias]

Who really knows what they didn't like,just trying to give ideas but since you do have been using mulch,you probably know the problems I mentioned.

Pine bark isnt oily in general,doesnt give me any such sense,at least the ones i have been using. Maybe when heated a lot from the sun you can get a slight oily feeling but nothing worth mentioning. And after some rains,it starts absorbing water well and fast,aiding in its breakdown.

Wish your palms fast and good growth!

tnx for your wishes, wish you the same!

[tank]

Pine bark is acidic and will lower the ph of your soil. I assume this is universal for all pine species. I pretty much use pine bark exclusively at my house.

[Jonathan]

Just out of interest - has anyone tried wood ash on C. media?

When I saw them in habitat in North Queensland they were always growing in fire prone grassland or light Eucalypt forest.

They invariably had burnt black trunks, so there would be a large ammount of potasium in the soil I would think.

Wood ash is alkaline...which would seem to suggest the opposite of what you guys are suggesting with the pine bark.

Wondering whether the effect you are noticing is from K rather than pH?

Pine bark seems to have naturally high K levels.

Check out this abstract http://hortsci.ashspublications.org/content/25/9/1074.4.short?related-urls=yes&legid=hortsci;25/9/1074-c it would be interesting to read the rest of this.

Loran Whitelock in his book 'The Cycads' says of C. media..."Cycads observed in areas where no fire has burned for several years look unhealthy and do not produce large crops of seeds".

So if you really love your C. media - set fire to it!

Cheers,

Jonathan

[Phoenikakias]

Jonathan that sounds very interesting! Your explanation could complete the whole puzzle, given that this year I have provided palms subjected to pine bark mulching with extra potasium and magnesium fertilizer, if overrated potasium (caused by the mulching) can cause the symptoms I have described above. Your explanation fits also to the treatment of palms after removal of pine bark, since dolomite is known to contain mainly magnesium and calcium and potasium in overdose can bind magnesium from the palms.

[Jonathan]

My sandy soil is low in every element and acid pH as well, so I'm using ash from our fire whenever it needs to be cleaned out, right around the palms.

Not sure if it makes any difference yet, time will tell.

Certainly there has been no negative effect at this stage.

Cheers,

Jonathan

[tank]

Just out of interest - has anyone tried wood ash on C. media?

When I saw them in habitat in North Queensland they were always growing in fire prone grassland or light Eucalypt forest.

They invariably had burnt black trunks, so there would be a large ammount of potasium in the soil I would think.

Wood ash is alkaline...which would seem to suggest the opposite of what you guys are suggesting with the pine bark.

Wondering whether the effect you are noticing is from K rather than pH?

Pine bark seems to have naturally high K levels.

Check out this abstract http://hortsci.ashspublications.org/content/25/9/1074.4.short?related-urls=yes&legid=hortsci;25/9/1074-c it would be interesting to read the rest of this.

Loran Whitelock in his book 'The Cycads' says of C. media..."Cycads observed in areas where no fire has burned for several years look unhealthy and do not produce large crops of seeds".

So if you really love your C. media - set fire to it!

Cheers,

Jonathan

Jonathan,

Just to clarify, pine bark and needles are acidic. Wood ash is basic. In a pine ecosystem (at least in the SE US) the soil is typically acidic and fire dependent. After a fire event the thought is that the ash causes the top layer of the soil to be basic, inhibiting germination and growth of plants that would compete, giving time for the established plants to put on new growth and then shade out the competitors. Wasn't sure if you were saying pine tree "material" is basic.

Helped a friend do a couple of controlled burns on his property and its amazing to see the new lush growth afterwards. Seranoa repens will have all of their leaves torched off and their trunks charred after a burn and within a few days will explode in new growth. Burn basically cleans away non fire dependent species that could compete. In our area these are typically laurel and water oaks. I imagine the same thing is happens with these fire dependent cycads. Often seed germination is dependent on fire as well.

[Jonathan]

Jason,

I wasn't saying that pine is basic, I know its acid, just that the guys here may have been attributing the effect of the pine park on the cycads to pH decline rather than K increase.

Interesting about Serenoa, makes you think there must be a lot of cultural tricks that we could try if we knew more about particular species natural habitat.

Cheers,

Jonathan

[tank]

Jason,

I wasn't saying that pine is basic, I know its acid, just that the guys here may have been attributing the effect of the pine park on the cycads to pH decline rather than K increase.

Interesting about Serenoa, makes you think there must be a lot of cultural tricks that we could try if we knew more about particular species natural habitat.

Cheers,

Jonathan

Jonathan,

Here is a cool picture of what it looks like a week or so after a burn. The picture is from Southwest Florida, near the coast.

http://www.naplesnews.com/photos/2013/jan/03/432847/

[Jonathan]

Jason,

That's pretty full on isn't it! They must be tough little buggers alright.

A lot of the Livistona species I saw in Queensland were also burnt, particulary nitida, muelleri and fulva.

I imagine that species like Jubaea and some of the dry habitat Madagascar palms would have similar adaptations.

Cheers,

Jonathan