Potting soil for palms

David Schweden · 21.07.2014 10:31

I wonder if you can give me/us some guidelines on soil to use for palms? We all need to know what soil to use when potting up.

I have received some palms from you in a very coarse mix that from the top looks like mostly gravel, and some quite heavy with much soil (peat and/or loam), and one small pot with gravel and peat on the top.

I read at multiple sites and books how important drainage is to palms. But apparently that's just one more myth. I read in A C Bunt's classic book on potting sol from 1988 how plants have different requirements on aeration, from 2% to 20% air filled pores, and palms and roses have among the lowest requirements, 2-5%.

But there might be another reason for coarse material: With palms most growers recommend to keep old soil when potting up (which might be 2 years apart, and never for big palms) and add new soil around root ball, which means the old soil should be designed to last for many years. The only stuff that lasts so long is coarse minerals. And I read you need enough coarse material to assure powdery materials (like clay and humus) doesn't fill all gaps, since air is in those gaps. Most people use peat based soil mixes, but those will break down as will bark etc. But you also need some ingredent for water retention and CEC (cation exchange capacity).

So one idea I have is to use e g 2-3 mm sized sand/grit and mix it with humus (or maybe clay if I could find some that is clean). A bit tricky to find humus as well but peat mixes with light and dark peat are available, as is bark mulch (although composted only for about a year, full of big bits), maybe I could sieve that? And add some humus to the top each year and let it migrate downwards by watering it?

That's my thoughts on a long lasting mix. But maybe you have something quite different in mind?

(Maybe you already wrote about this, but I searched for Umtopfen and Erde and found nothing.)

ufa · 21.07.2014 23:29

Hi,
as you've mentioned correctly, organic materials like peat and humus will break down after a few years.
From my experience, humus / compost in deeper layers gets mouldy (might be ok if aged for a few years), therefore I prefer peat if I want to mix in organic material. I suppose, bark dug in breeds even more fungi (and the decomposition of bark binds nitrogen temporarily).

Water retention capabilities are well provided by loam or clay, while a substantial addition of sand to the loam or clay will break up the otherwise too heavy and dense stuff. I am with you (or your source) that (most) palms would not need an airy substrate (however, your / the individual palm kind's mileage may vary).

The mixture I pot my (bigger) palms into is thus (approx., by mass parts): 5...6 loam / loamy soil from my garden, 2..3 sand (very fine grained I used to use), 1 lava grit (sold for gritting pavements in winter, at least around here), 1 peat.
I use to add some organic fertilizer ("Blood, Fish, and Bone" stuff).

ufa

Palme Per Paket · 22.07.2014 20:22

Hi David,

Please check these threads for more info on substrates:

http://www.palmenforum.de/viewtopic.php?id=2545

http://www.palmenforum.de/viewtopic.php?id=837

http://www.palmenforum.de/viewtopic.php?id=2228

Here are also some instructions on how to mix yourself.

Best, TOBY

David Schweden · 03.08.2014 18:04

Thanks.

Here's some more info I found:

I read that in time there will be roots in all of the pot coarse enough to do the job that the coarse peat etc did for aeration, so the goal should be to design the soil so that it breaks down at a rate that matches that. I also read that at that point, powdery contents like humus will be washed out anyway.

And that microbial activity is important for best growth, most of that is much less important for a potted plant with mineral fertilizer, but not all. So for that reason all-mineral is less good. And that one could try it anyway but then probably need organic fert to make it work well, and that gives you a new set of problems.

The two most long lasting organic materials are peat and uncomposted bark, I think I'll use mainly one of those plus coarse sand.

I also saw Tobias S published a book aa while ago which is freely available as pdf on this site in where he describes 2 recipes on soil, one for palms from dry areas and one for those from wetter areas. It differs slightly from that on the link he gave us above. Still loam though. I'm hoping to avoid that.

Tobias mentions coconut substrates as alternative to peat (and bark), I read coconut fibres have CEC and water holding capacity rather similar to peat, don't know about longevity though, peat has wax built-in which prolongs its life as soil substrate and bark has some other such protection. And my data is for coco fibres not coco shells (Coir) for that I have no data. I have been able to find Kokohum on German sites but not CocoBlock and it doesn't say if it's fibres or shells. I'll probably use peat anyway, at least that's my main plan for now.

Alcibiades · 03.08.2014 20:31

Hello David,

i already told you my preferred potting mix on Palmtalk. smile

I have made bad experiences with Kokohum last year and i wont use it again. If you want a potting mix for very young palms i would start with a a base of Perlite and sand. Add Pinebark, barkhumus, peat moss, lava and pumice.

LG; Jakob

David Schweden · 10.07.2017 18:40

Palme Per Paket schrieb:

instructions on how to mix yourself.

Hope Toby sees this!

I just wonder why you add quarz sand if you already put Vermiculite or Seramis in there? Why not just replace the quarz sand with more Vermiculite? Is it because quarz sand is sharp so that it produces bigger cavities? Or because you want some more weight?

Thanks

David in Sweden

Palmenforum.de

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#1 21.07.2014 10:31

Potting soil for palms

#2 21.07.2014 23:29

Re: Potting soil for palms

#3 22.07.2014 20:22

Re: Potting soil for palms

#4 03.08.2014 18:04

Re: Potting soil for palms

#5 03.08.2014 20:31

Re: Potting soil for palms

#6 10.07.2017 18:40

Re: Potting soil for palms

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