Greenhouse: Greenhouse Citrus, 1 by stressbaby

stressbaby wrote:
Tammy asked about a CHC-based (coconut husk chip) potting medium for citrus. I thought I would give the mix and some links and information in a new thread. Sorry if it's too long and complicated.

First a disclaimer: I'm no citrus expert. What I know about container citrus culture is more from my failures than my successes. And from reading. Lots of reading.

Why CHC? It holds something like 7 times its weight in water, yet it drains exceptionally well. It breaks down very slowly over years, as compared to months for pine bark, so a CHC medium will not compact. This is important for root rot-prone plants like citrus. It is hard to overwater this mix. Those who have used it for a while claim terrific results with greenhouse citrus.

Why not use CHC? The mix without the additives has virtually no nutrient value, so plants are totally dependent on the gardener and his/her additives for nutrition. And the ingredients are hard to find. And it is a pain to prepare this mix.

Here is the (KFC) Original Recipe, courtesy of Millet, formerly of the GW:

4 parts presoaked, rinsed CHC, either small (1/4" chips) or medium (1/2" chips)
1 part peat

To remove salts from the chips, they should be soaked and rinsed three times. I do this in a 5 gallon bucket, but others do this in a kiddie pool in the yard. On the final rinse CaNO3 and Mg SO4 (epsom salts) should be added.
Here is a link describing the process: http://ladyslipper.com/coco3.htm
Here is a link with the CHC source I use: http://www.growstuffplus.com/IBS/SimpleCat/Product/asp/produ...

To 1/2 cu ft (3 gallons) of the above mix you add:

18g STEM (soluble trace element mix)
18g soluble fertilizer without minors
110g dolomite
130g 12 month slow release 23-4-8 fertilizer

This will make enough mix for a 12" clay pot.

I made some adjustments in my mix. I used CHC, peat, and composted manure at ratios of 3:1:1. This mix can be a little soggy if you are not careful with the water, and so with my next batch I'll probably go to a ratio of 4:1:1 or 5:1:1. To 1/2 cu ft of this mix I added:

100g dolomite
15g (2tsp) Micromax, a slow release trace element mix
2T Miracid (no minors)
60g (4T) Osmocote PLUS 3-4 month 15-9-12 fertilizer

Yeah, I know, sounds like chemistry class! But this mix is working great for my new trees. I went way low on the fert and the minors in my first batch 3 months ago and my two older trees suffered badly. I repotted those two yesterday.

Most people still use a water soluble fertilizer once a month or so for additional feedings. I'll add iron every couple of months to the water, too.