There are plastic drainage flat that goes in alot of store bought plants....looks like a frisbee with holes. Personally, I like the more natural, sustainable materials. Best way, I have found, is bark, or big pieces of mulch at the bottom of the pot. Depending on what is growing in the pot, river stones at the bottom also work well. Or a mix of bark and stones. Not only do they help with drainage and root rot, it keeps the the dirt from being right on the holes, make sure you dont cover the holes at the bottom where the h20 will not drain at all. If you add organic matter, such as peet or mulch, it will decay un the boottom and eventually turn to found for the plant. If you use sea shells at the bottom, make sure its home is for a plant native to salt water coast, one or two is okay, but alot of seashells can throw the PH off in the soil. I also have used a pine bark mulch, eggshells, hummus, manure and sand/dirt mix for indoor or outdoor containerplants to gow in and they are happy plants. Hope any of this helps. If you don't transplant the plant to add a mulch or rock bottom, a little cheese cloth on the hole works, or a piece of an old sock. LOL.