Optimum soil blends for indoor use.

There are today a lot of soil blends on the market. Various vendors offer mixes with such things as worm castings and bat guano. However, none of them state the percentage content of such substances, and they never will. So, if you want to know exactly what is in your soil, you must blend it yourself.

The starting point of any blend is what percentage of various base ingredients to use. I like to keep things simple so I blend pre-fabricated products to attain specific performance goals within the context of minimal expense.

In this case, Pro-mix BX is half the price (once expanded) of coco coir (Botanicare brand). The coir has the benefits of both easily wetting and holding a lot of water. Using a 5:2 ratio of Pro-mix to coir results in a blend that fully retains the watering benefits of coir. Could less coir be used? The less coir used the better, on a cost basis. (Note that this mix is amended with worm castings, guanos, and whatever other organic amendments that I have available. These additives affect the water retention properties of the mix.)

Pure Pro-mix does not re-wet easily, even after the initial saturation. Using it in pure form in ebb/flow hydro, it can take an hour of low-level flooding to get it decently saturated. In contrast, coir will wick up the max amount of water possible in less than ten minutes.

Any comments on peat/coir ratios or pre-fabricated blends are appreciated.

I want to use square pots w/organic mix on an ebb/flow table. The pots will only be flooded to maybe an inch or so depth with plain water. A little experience with Botanicare high pith Cocogro indicates that the coco will wick up plenty of water in a short time period.

Despite considerable research, I have not found a soil mix recipe that meets my criteria:

1. Includes cocogro for wicking and water retention.
2. May include pro-mix bx or equivalent, only if needed.
3. Includes either an organic fertilizer and/or organic amendments that are sufficient for the full growth cycle with only plain water.

In the past, I have had excellent results with pro-mix amended with guanos, worm castings, and some Rainbow Mix Grow organic fertilizer watered from the top. Problem with this recipe is, the pro-mix does not wick up water from the bottom very well. I've flooded it for an hour and it still wasn't as wet as top-watering.

So I added cocogro at a 2:5 ratio (coco/pro-mix). This ratio holds plenty of water and wets easily, but the plants are not responding favorably. That makes me hesitant to use an amended "coco only" mix as I think that might be too dense a mixture.

Any ideas for recipe improvement appreciated.