It’s very common for people to layer rocks at the bottom of pots to help with drainage. Using rocks for drainage in pots can actually cause more damage to your plants health than good. It’s easy to think that using rocks for drainage allows the water to sit between the rocks and not at the bottom of the soil but in reality, it just causes the water to sit higher and closer to the roots.
Do rocks improve drainage?
Since rocks raise the level of wet soil, using rocks to improve drainage doesn’t necessarily work and can increase your plants risk of getting root rot. Soil is kind of like a sponge and won’t drain any water until it’s completely full. The soil will only start draining when it can no longer hold anymore water so using rocks to assist with drainage doesn’t help or make it happen any faster. Rocks also raise the soil making it sit up further into the pot and since the water will naturally settle at the bottom of the pot, that wet soil is sitting up higher and closer to the roots, making it as if it’s a smaller pot.
Alternative methods for drainage
Using a soil that has better drainage will assist in keeping your plants happy. It’s best to choose a high quality soil that is well draining or make up your own as well as using a pot that has good drainage. Adding perlite to any good quality potting soil will help assist with better drainage as well as aerate the soil.
If you were using rocks to try and stop soil from escaping the pot or you just want to put something at the bottom of the pot to stop soil from washing out you can use paper coffee filters. Coffee filters are designed and used to let water drain through them while keeping solid material from escaping.
Using rocks in pots
If you’re wanting to use rocks with your plants, you can put them in the drainage tray or decorative pots. Using rocks in drainage trays or the decorative pots and placing your plant pot on top will catch water as well as help increase the humidity without your plants roots sitting in any water.
Rocks in non-draining pots
Some people like to put rocks in the bottom of pots that don’t have any drainage holes to use as an internal drainage tray. While for some people this may work, but for others it can just lead to problems like over-watering, poor growth and diseases. Since you can’t see the rocks or if the soil is even draining, you can accidentally overwater your plant, causing it to become waterlogged and increase the chance of root rot. When using pots that don’t have any drainage holes, it can lead to aeration problems within the soil and can cause the plant to have slow/poor growth or to not have any growth at all and with no proper drainage or aeration it can also lead to diseases such as mould.
Using rocks to assist with drainage is very popular and for some people it may work very well but for others it may not and there is that chance that it can cause problems for your plants.