In article , eetmail-
says...
Any gravel or sand 2-3 mm or smaller that allows plants to root in it is
fine for a basic planted tank. Plants can't root and spread in pebbly
gravel. If you use plain gravel, you need to put laterite (an iron rich
clay) tablets at the roots of crypts and swordplants. There are some
new high-tech substrates, Fluorish, Eco Complete, and Onyx, which are
porous clay with minerals plants need at a particle size designed for
plant roots. If you use one, you don't have to fertilize the substrate.

I used Eco-Complete mixed with sand and was very satisfied with it. It
is a little pricy, but sure makes the plants happy.

BTW, as we've discussed here before, if you take traction sand and sieve
out the really fine stuff, you've got the right size of coarse sand or
fine gravel you need for plants. It may be too late to get any this
spring unless you live in the far north, but it's hard to beat the
price. IIRC, I paid $5 for a 60 pound bag.

--
Homo sapiens is a goal, not a description