I would buy natural gravel or sand that is sold in petshops. Rinse thoroughly before using.I used to have pieces of Water Sprite that wasn't planted. They floated and grew right out of water. And all I had for lighting was a simple incandescent light!

I agree about using a natural substrate, but am also a balanced aquarium lover, so have gone to some extremes with combinations of soil, clay and coarse sand to create them.

However, if you don't want to break down the tank to install a proper substrate, you can grow aquatic plants in totally bare tanks and just about every breeder I know does just that in fry and grow out tanks, using unglazed clay pots. For plants that propigate with runners, shallow azelia pots are best, as you don't need depth so much as surface area for them.

I played around with different sized pots and potting mixtures for quite a while before I came up with what seems to work best in just about every tank, starting with a small roll of fiberglass screening. Cut a piece to fit the bottoms of the pot, then cover it with 1/2 inch of well washed, coarse sand. Dampen and pack the sand.

Follow that with sterilized potting soil to just cover the roots, leaving the crown of the plant well exposed. Then, add more of the coarse sand to cover the soil, up to just a hair below the top of the crown.

Leave at least 1 inch between the top of the sand and the rim of the pot and add just enough of your current nuggets to cover the sand. Unless you keep fish that dig, that's really just to prevent the sand from spilling out when you handle the pots.

But before you pot, get some aquatic plant feeders in tablet form and put one below the roots, but not touching them. If in any doubt, use only a part of one, as too little is better then too much and as the plants sit in the tank, they will absorb nutrents from the water, and one of the reasons why unglazed clay is better for this purpose than plastic. The clay is porous. The other, is weight. It would take a huge aquarium fish to tip one over.

Given enough light, you should get a lot of lush growth.

Thanks for the feedback.

I bought a few potted aquarium plants online and will see how they do for now.
A planted breeder tank seems like a good idea! I think I have an extra 10 gal tank lying around. gotta look for it.