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Coccothrinax seedlings


David_Sweden

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End of August 2016 I got 10 Coccothrinax Miraguama seeds from Zadengigant and 15 Rhapis Multifida from Seedman. One week later I discovered that Rarepalmseeds had just gotten some fresh Cocco M so I bought 30 of them plus 30 Cocco Fragrans (but got ~20% extra). In September I "planted" most of them in ziplock bags with damp paper towel (1-2 each) except 21 Cocco F and 33 Cocco M from RPS which I dumped collectively in 2 bags with moist soil. By Oct 16th the first had germinated: Two Cocco F and on Cocco M from RPS. In December I moved them germinated ones to "rootrainers" 10cm deep:

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8 Cocco M and 21 Cocco F, of which 1+5 from paper towel bags. None had leaves yet. The ones from Zadengigant and Seedman never grew. CFLs giving 2-2.5klx. For all my plants I use liquid fert every watering, ½ the recommended dose; with these, no fert until Dec 19th (1/4 dose) and ½ dose from Jan 19th. Over time I lost all but 2 Cocco M and 15 Cocco F.

March 26th I repotted them to pot trays 14cm deep. Growth rate for leaves~1cm/week. May 17th I moved them from the artificially lit corner to a sunny (SSW) window. By mid July they were still perfectly green, but at the end of July some brown dry streaks started to appear:

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Aug 16th I moved them back to the old corner, where they have been since, but now with a CDM spot giving 3-12 klx, and 1st week in Sep it struck my mind I should leach them so I did that and switched to lower dose: Either 1/4 dose or ½ dose followed by pure RO water ½ pot volume. Nov 25th I repotted all but 3 Cocco F to bigger pots using a coir/seramis mix. Some Cocco F had 3-way leaves since long. The brown streaks kept getting worse though, and now all Cocco F have it but none of the Cocco M.

 

Edited by David_Sweden
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170815t.thumb.jpg.0add6cb0b5cebe13eaeb2a  180210t.thumb.jpg.dfeb9d450185ebc3154fc2

Pic from repotting:

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The first several months I thought this could all be explained by too much fert or that repotting should help, but it hasn't stopped. Reading about such spots and possible Coccothrinax sensitivity it sounded like it could be either fungus or dryness, which are like the opposites of eachother.

I read at Palmpedia about how both species live on savannas, and then I though that even if seedlings might not endure dry spells as well as grown ones, considering the time it takes for them to grow and that my seedlings now are almost 1½ years old they must have some drought endurance to survive on a savanna. So I have performed 3 experiments to get wiser:

On Feb 9th I watered all the ones in coir, and again on the 16th except for the one furthest away to the right, lets call this the "dry one". Thus far, I had watered them when slightly moist (using moisture meter), which means 7-8 days in between lately, but now I left them all without water until March 8th. By March 3rd the surface of "the dry one" was finally all dry also at the edges but if I poked at the corners even 1-2mm down it was a bit moist, but just close to the corners. The soil is quite dry at the center I believe. So from Feb 9th to March 8th without water for "the dry one" which is 27 days, and for the others 20 days.

In general I couldn't see them suffering "more than usual" during the dry spell, and mostly I had my eyes on "the dry one" in the corner which thus far had no brown streaks, just a few mm dry tips on 2 leaves; most of all I looked at the perfectly green tip of the leftmost leaf. What I didn't notice at first was 2 thin brown streaks emerging on this leaf at the bottom (it is the plant to the right):

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The corner doesn't get the best ventilation so I added a fan Feb 12th to stir it up. Humidity is regulated to 40-50%RH (but up to 60% RH a couple of hours every morning when I boil water), humidifier is close to these plants but I can't imagine the "steam" (which is cold steam, from ultrasonic transducer) reaching them directly, I can see how it falls to the floor (the humidifier and the CDM lamp is on the loudspeaker):

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The 3rd experiment was to place 2 massively big drops of fertilized water on 2 green leaves (look hard and you will see them at the 2 leaves arcing at the top):

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To this day they remain perfectly green. So I think it is safe to rule out fungus (in combination with high humidity). So I'm thinking the reason should be related to dryness in some way, where by dryness I mean any combination of dry soil, dry air, salty soil, too much fertilizer. Or possibly imbalance in fertilizer (which in turn could be due to high pH). Coir is not as well tried out as peat moss. I added some Ca and Mg to my normal fert. pH is rather high (I measured 6,3 for the coir itself and 5,9 for the coir/seramis mix, using a calibrated digital 2-digit glass probe pH meter and SME method) but I only measured it for the soil mix not with fert & roots.

Right now I am thinking that maybe an even lower fert dose is a good idea, like 1/8 dose (either that or leach very often). And to let it dry out between waterings pretty much although not as much as in my 27 day test, but maybe 2 weeks between waterings. And forget about the fan & fungus.

All in all these are the slowest and most sensitive plants I ever saw, and any tips are welcome. Pity when leaves turn brown now when the nice 3- or even 4-way leaves have started to appear.

 

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Sorry for some typos, pH meter has 2 decimals not 2 digits (and calibrated at pH 4 and 7 after each measurement). Anyway, main point of this thread was hoping to hear of similar experience with the brown streaks, and to share pics of these slow and relatively unusual palm seedlings which look very nice even when very small (which seems to mean over 2 years old due to the sloow speed :wacko:). Meanwhile the Chamaedorea Radicalis planted the same week (seen behind the Coccos) are very fast and never complain about anything, the last ones will leave the rootrainers for bigger pots this week but they don't even mind.

I found some interesting threads on Coccothrinaxes earlier which I forgot to mention: Here main theory is too much fert or lack of water. Here consensus is overwatering (and to give it more sun) nbt MattyB does mention he goes "pretty light on fert " (slow-release) but he doesn't say "very low". Here it sounds possible it got a bit much fert. And here is a healthy Coccothrinax growing on rock with little soil. There are also several threads on fungus (and too much water and moisture) but I don't think that is my problem (and in those cases they seem to get black spots not dry streaks). Makes me see a pattern: They can grow where there is almost no soil meaning very little nutrition and they are maybe even used to that. So maybe they are extremely sensitive to over fertilization (or salinity)?

And I have so far stuck to liquid fert every watering for all plants but for those being watered only every 2 weeks maybe even I should consider slow-release fert to optimize growth - or maybe it doesn't help, soil is probably rather dry after 1 week so it doesn't grow much anyway. Doesn't fix brown streaks in any case.

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