Let’s talk about drainage layers! The myth that a drainage layer is important for your potted plants has been around for decades and is believed and shared by tons of great plant parents (it was even on an episode of Mr. Rogers!), but they’ve been shown to not actually help your plants and can even harm them! Keep reading to learn all about it!
Putting a layer of gravel or pebbles or potting shards at the bottom of a pot will improve drainage and/or can take the place of a drainage hole in a pot without one.
Drainage layers do NOT improve drainage, they actually make it worse. Studies have shown that water does not move easily from a finer to a more course material, so it’s difficult for the water to move from potting mix (a finer material) to the drainage layer (a courser material). That means using a drainage layer will actually keep your potting mix more waterlogged, not less.
So in a pot with a drainage hole, a drainage layer is actually keeping your potting mix from draining well and releasing the excess water out of the hole. In a pot without a drainage hole, it’s actually even worse. Not only does the water in the potting mix not drain well into that drainage layer, but the initial water that actually makes it down there has nowhere to go, especially in pots made from non-porous materials.
This means there’s a little pool of water at bottom of the pot that is waiting for your plant’s roots to grow down into it and if they can’t drink it up fast enough, they’re going to suffocate and get root rot. The bottom line is that even though this has been something recommended in many books, by many companies, and many people, drainage layers just aren’t doing any good and actually can do harm.
And if you still have doubts, remember: no grower ever grows a plant in a pot with a drainage layer or in a pot without many drainage holes! If this was a good system, the people who make their money off of growing healthy plants really quickly, efficiently, and well would be doing it.
The Bottom Line:
So, you’ve got a gorgeous pot without a drainage hole... Now What?
- Use the gorgeous pot as a cache pot, keeping your plant in a plastic grow pot with plenty of great drainage holes and slipping it into the pot without a drainage hole as a decorative cover pot. Remove the grow pot to water.
- Drill at least one, preferably several, holes in the bottom of the pot.
- If the pot is clear glass and you don’t feel comfortable drilling it, use a clear, plastic liner with holes as the “grow” pot so you can still see straight thru to the potting mix (orchids are often sold like this).
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