Plan to mix it 50/50 with peat. Which sand is the right one? I have the choice of:
- Pool filter sand
- Play sand
- All-purpose sand
- Paver sand
- Desert sand
Peat is the problem. Any sand. Not peat!! Use Perlite, Diotameaous earth or Turface, pine bark fines, but NOT peat! Peat is the thing that dries and makes the water pool on top, drain down the sides, and NEVER get to the plant! It's OK if you are making a hypertufa pot, but for a soil... BAD!!
But Janie said she uses a 50/50 mix of peat and perlite for her propagation boxes with a high rate of success. I gotta do what Janie did! Here's a link to the famous thread: Janie's Easy Propagation Chamber
the peat has to stay moist. whenever you let it dry out, it forms a crust and repels water. In the propagation chamber, because the lid stays on most of the time, and because of the reservoir in the middle, the peat will never (or should not) dry out. When I use sand, I use washed play sand - any type or sand should work. The chamber uses the same principle as the 'Forsythe pot' only it has a cover to better retain humidity.
Just be sure that the sand you get did not come off of the beach. If it has sea salt in it, it will probably kill your plants.
If you happen to be in an area where you can buy decomposed granite, that works well, because it is course grained.
Your sand is for drainage, so the fine sand is less useful than a larger grained sand (if that helps).
I just mixed up a batch of sand with coir and a little bit of Miracle Grow potting soil. It looks nice, but this is the first batch, so I don't know yet how it works.