Clay in house plant soil

Hello All
I would like some feed back on an idea i have. That being incorporating some clay into house plant soil. The reason for doing this is - in my theory - to increase the ability of your houseplant soil to retain fertilizer I'm thiniking primarily nitorgen or other things that are fast dissolving.

The obstacle of course would be that the soil no longer drains well. However my own experience is that soil mix with compost and rock dust - with the addition of a few percent clay - actually increases its ability to drain if left to mingle for a week before use. I actually used a higher percent clay in one trial - with one 3rd clay rich garden soil, one 3rd peat and one 3rd sand (i think this was the mixture but can't remember precisely -i may have used some perlite or vermiculite, but about 1/3 clay rich garden soil). The resulting mixture increased in drainage to this day - it is now very dense but drains fine.

I also believe the clay can bring out different genetic expression in some house plants so may be neat to try.

My ultimate goal is to be able to feed my houseplants kitchen scraps in some form or other as organic fertilizer, maybe compost.

One more thing to add, rock dust increases the drainage of clay as we'd all expect - even in small proportions like 1/5 clay to rock dust (can't tremember exactly). However rock dust is kindof hard to come by sometimes. So i also tried wahsed ashes which also increase the drainage, i belived because of its shape, not chemistry. However, i am a little reluctant to start adding much ash to my house plants as I don't know much about it's (at least in my mind) relatively potent chemical action.

Just thought i would post this to see if anybody wanted to add anything or perhaps do some experiments themselves, i personally suspect something useful could come of it. I noticed the most common soil science for tropicals is soiless type soil, and noone is talking about adding clay - rather silica gel...why not just add some clay.

Hi Mike,

For my indoor gardening under lights I use Premier ProMix BX, a commercial potting medium (and a product of Canada). It works well for me, so I have no need to experiment.

The philosophy there is "if it is not broke, don't fix it." Don't forget, plant roots need oxygen. And a reasonable pH.

But do keep us informed of any breakthroughs in your experiments.

ZM

Yeah, I like promix too. I've heard good things about it and it seems to work quite well. But i plan on doing some further experiments with the clay addition to basic potting soil. Clay, river silt, black dirt (hopefully that term isn't offensive around here - just kidding).

What happens if you leave the plants in the promix for five years, and how long can it go unfertilized?

This message was edited Jul 2, 2021 3:25 AM

Hi Mike,

I have no idea what happens if you leave the plants in ProMix (or anything else) for five years. I grow only annuals in pots. Primarily zinnias and tomatoes. And some of them get set in the garden after a month or so.

" ...and how long can it go unfertilized? "

ProMix contains only a very small amount of nutrients, enough to support new seedlings for only a few days. I water it with soluble nutrients, including some Calcium nitrate.

I breed zinnias as a hobby, and I can grow zinnias indoors under lights from seed to home hybridized seed in ProMix. I use a complete formula of soluble nutrients in the water I use. I can grow two generations of zinnias indoors during the Winter (in ProMix). In addition to another two generations outdoors (in garden soil). That lets me breed new zinnias that are not available commercially.

ZM

Promix typically lasts one to two weeks after applied, depending on the rate at which the manufacturer mixes it, the amount of water delivered to plants, and plant uptake.

Hi Mark,

I don't "apply" ProMix. I fill pots with it and grow plants in the pots. And I do water the ProMix with water with dissolved added nutrients, because the ProMix has very little nutrients, by design. If I transplant the plant to my garden, the ProMix becomes part of the garden soil.

ZM

This message was edited Jul 22, 2021 9:55 AM