Is there something that can be mixed into topsoil to make it drain well in flower pots?
A combination of: sphagnum moss pearlite vermiculite will lighten top soil, but you'll need a lot.1 part soil to at least 4 parts lighteners suggest you trash the topsoil and buy Potting Soil, cheaper than amending top soil.
If you are using real top soil then you will to add some vermiculite, that is the white pellets in potting soil. You can also use sand but the vermiculite is much lighter. Make your own potting soil with 2 parts compost, 1 part sand and 1 part vermiculite.
Hi Victoria, You can increase the drainage capacity of any soil mix by increasing its porosity. To do that you can mix any relatively large grained material throughout the soil. Perlite is one of the favored porous materials because it doesn't break down or collapse easily, as Vermiculite does. Ground bark chips, sand, fine gravel and coir (coconut husk) are also used to add porosity. The key here is to mix this material throughout the potting soil. The out-dated notion of adding drainage material to the bottom of the pot has been discredited. In fact, all that does is to shorten the rootball, which decreases the porosity and drainage of the soil. It would also add that taller pots, drain better than squaty pots.
