A new soil mix question

[JT in Japan]

All, 

I've been re-reading all the excellent advice in other threads re: soil mix. Especially the epic "your soil mix" (http://www.palmtalk.org/forum/index.php?/topic/48442-your-soil-mix-tell-us/&page=3)

 

But I have a situation that isn't addressed, and that I'm worrying about. I'm about to purchase a truck load of soil from a professional hibiscus grower, and he tells me that it's about 30% peat, and he worries it's maybe too water-retentive for my palms. I want to buy the mix because it's the right price, and I also want to use it for all my repotting, across 4 different palms. I'm going to pot up about 600 seedlings, of 4 genera: Arch. cunninghamiana, 2) Phoenix reclinata 3) phoenix rupicola, and 4) trachycarpus fortunei.

 

A couple of questions:

1) if it's good enough for hibiscus, is it good enough for me? This story says "Hibiscus does not grow well in wet, waterlogged conditions, preferring soils that are moist but well-drained. Loam and sandy loam soils tend to be the best." (http://homeguides.sfgate.com/type-soil-hibiscus-flowers-41769.html). That sounds perfect for palms, no? And this guy makes his living on his plants, so I assume he's doing it right.

 

2) rather than settling for just "good enough," what can I add to the mix to a) lessen the water retention, or increase the drainage?

 

Thanks,

JT

[JT in Japan]

I took a sample of the mix and put it in a couple pots and watered it. After two hours, the volume had shrunk by 1/3 (absorbing a lot of water), and when I turned the pot, the mix held its own shape very firmly. It feels really moist, fully saturated. To my uneducated eye, this is really wet soil.

[Hamal]

So it is 30% peat, what is the rest? It looks like it might contain a lot of loam. I would check the drainage, which to me is most important.

My soil mix contains 30% peat as well for palms like you mentioned, but 70% is a mineral substrate with optimal drainage. In my case it is crushed burned clay, but you can also use pumice or something similar. The peat retains most of the water, while the crushed burned clay oxygenates the substrate and hold only very little water. Without the peat it would be dry in less than 12 hours in the sun.

[Phoenikakias]

Agree with Hamal. Your soil looks to my eyes to wet!

[Monòver]

May be this soil is too wet, but you will plant Archis, they love water. And Trachycarpus, reclinatas and rupicolas are like stones, strong palms.

I think this soil will be good for you if you plant the seedling now in a small pots. This soils could be dangerous in a cold and wet winters, but if you plant now, the palms will grow and the next winter you will have "big" palms in a small pots. This is good, because the drainage will be better and the palm could drink the excesive moisture.

But i think if you mix more perlite or burned clay, will be the best.

[JT in Japan]

I like your suggestions, Antonio, but I think the mix is just too absorbent. But you make a good point about the trachycarpus and Phoenix... Maybe they're strong enough to handle a summer of heat and water? They're all about 8 months old by now. I have to think more.

jt

[Phoenikakias]

4 hours ago, JT in Japan said:

I like your suggestions, Antonio, but I think the mix is just too absorbent. But you make a good point about the trachycarpus and Phoenix... Maybe they're strong enough to handle a summer of heat and water? They're all about 8 months old by now. I have to think more.

jt

Better water more frequently than risk a root rot even by using smaller pots.

[earthworm73]

I have had good luck with a formula of 5:1:1 (5 parts pine/conifer bark, 1 park "soil" (peat, coco, compost), and 1 part perlite (large size). This will hold enough moisture but allow for very good drainage and oxygen for the roots. Just adjust the percentages as need for individual palm species.

[Hamal]

I doubt your 5:1:1-mix will have really good drainage. It also depends on the size of the bark.

The problem with too much organic stuff in the substrate is that organic material will decompose, some sooner (like potting soil), some later (like pine bark or coco coir). Once that happens, it clogs the substrate and there is no more drainage. So it is key to use as little organic substrate as possible.

The other advantage of a substrate consisting of mineral components like pumice for the most part is, you can water and fertilize as much as you like. Even your neighbor who waters your plants while you are on vacation will not be able to water too much. You just tell them to do what you do, i.e. soak your plants every day.

[earthworm73]

3 hours ago, Hamal said:

I doubt your 5:1:1-mix will have really good drainage. It also depends on the size of the bark.

The problem with too much organic stuff in the substrate is that organic material will decompose, some sooner (like potting soil), some later (like pine bark or coco coir). Once that happens, it clogs the substrate and there is no more drainage. So it is key to use as little organic substrate as possible.

The other advantage of a substrate consisting of mineral components like pumice for the most part is, you can water and fertilize as much as you like. Even your neighbor who waters your plants while you are on vacation will not be able to water too much. You just tell them to do what you do, i.e. soak your plants every day.

Hamal I get what you are saying and that's true. The size of the bark is important that's why "fines" are better than "nuggets" etc. Believe me it does offer way better drainage than your standard bag o potting soil etc. The 5-1-1 mix is temporary and only good for a season or two at most due to the eventual breakdown. I have a small trachy that I'm not quite ready to plant in ground in that mix for the past season and a half and the peat based ingredient has broken down but most of the bark still looks like bark...albeit "tired".  For something more permanent I would go with something with more minerals and no peat-y stuff. Hamal I respect your input based on your obvious results.