We’ve all heard the advice to put gravel in the bottom of a plant pot, and some of us may even have done it. But gravel doesn’t improve drainage in any meaningful way, and you’re probably better off without it.
What Gravel Is Supposed To Do
Plants’ roots shouldn’t stay wet too long. Some plants like “well-drained” soil, where water doesn’t stick around very long. Others can tolerate more water, but unless a plant is truly aquatic, it won’t want to sit very long in a puddle of dirt soup.
Gravel does drain better than soil, because there are large spaces between the rocks. So what? Your plant isn’t planted in gravel, it’s planted in soil. The soil will hold just as much moisture whether there’s gravel beneath it or not.
Why You Should Skip The Gravel
If you fill part of the plant’s container with gravel, you’re reducing the amount of space for soil. Now the plant’s roots have less room to grow.
In a plant with a drainage hole, water will saturate the soil before dripping down the gravel and out through the drainage hole. Without the gravel, the soil still gets saturated, but then drips right out the hole. The gravel adds nothing to the equation.
Without a drainage hole, you might think the gravel creates a reservoir for water to pool underneath the soil. But the soil will be touching the gravel anyway, and will tend to seep in between the rocks over time.
Use a Coffee Filter If You’re Worried About Dirt Falling Out
Gravel’s other purpose is to put some space between the soil and the drainage hole. But we live in modern times, and we have better technology for that job than rocks.
Block the hole with something that lets water through, but not dirt. Some options:
- A coffee filter
- A piece of window screening
- Mesh fabric
The coffee filter will break down over time, but by that point the dirt will have settled and it will be less likely to fall out the bottom of the container.
What To Do If Your Pot Has No Drainage Holes
It’s hard to maintain good drainage without a hole in the bottom of the pot, so you really only have three options:
- Water very carefully. If you never over-water the plant, it doesn’t matter. Good luck.
- Create your own drainage holes. In a plastic pot, drill or poke holes with a suitable tool. For a ceramic pot, use a masonry drill bit.
- Use two pots. The outer pot, without a hole, can be your heirloom pottery. But inside that, use a pot with drainage holes. It can be the super cheap, lightweight plastic kind that costs cents at a garden store.
If you use two pots, you can easily take out the inner pot at watering time. Or put gravel at the bottom of the outer pot if you must, where you know the dirt won’t seep into it and you can inspect and empty it at any time.