Can I Use Garden Center Lava Rocks In My Hob Filter As Media?

*Flower pots don't need gravel in the lesser.* (Adobe Stock)

I've ever been told to put a layer of gravel in the bottom of a flower pot earlier planting. Is this really necessary?

Actually, information technology'due south a myth, merely information technology's 1 that fifty-fifty I believed for many years. The common belief is that a layer of gravel in the bottom of pots will improve drainage and keep the soil from spilling out, and besides, that'due south how we've always done it, then it must exist right.

Here are the facts well-nigh using gravel in potted plants.

Why Gravel Doesn't Improve Drainage

The gravel myth is based on a mistaken idea that it will increase drainage. Follow my logic hither and see if nosotros can debunk this idea:

Gravel vs. Soil: Gravel does drain h2o – obviously, water runs through gravel faster than soil. However, the opposite is as well true: soil holds water amend than gravel.

Soil Acts Like a Sponge: Water won't run out into the gravel, or out of the pot, or anywhere, until the soil is saturated. If you don't believe me, try laying a sponge on superlative of a pile of gravel, and so pour h2o into the sponge. Does the gravel make the sponge drain faster? No, the sponge fills up, and it won't drip until it tin can't concur another drop.

Not Enough Soil: Just like with a sponge, water naturally settles toward the bottom of the soil. But considering you've partially filled your pot with gravel, that soggy soil lesser is at present higher (and closer to your plant's roots). Basically it's like having a smaller pot!

Poor Results: Then, you end up with an unhappy, crowded plant sitting in too wet soil, and yous've wasted valuable pot infinite with gravel that's doing no good.

Drainage Fabricated Easy:

Your plants volition be happier if you lot uniformly increment the drainage of the soil itself. Choose high-quality potting soil that is well draining. And if your plants need even more drainage, instead of putting gravel in the bottom of your pot, attempt mixing in perlite, PermaTill, or organic matter into your potting soil to increase drainage throughout the pot.

Gardening Tip

If you're worried nigh soil washing out of the bottom of your pot, put a paper coffee filter, a piece of screen, or a shard of pottery over the holes before adding clay. Usually, though, drainage holes are pocket-sized plenty that this isn't a problem.

How to Use Gravel with Potted Plants

If you lot desire to put gravel to work with your potted plants, use information technology outside the pot. Put a layer of gravel in your plant'southward drainage tray, or down inside a decorative planter, and then sit your plant pot on superlative. The gravel will hold water and increase humidity, while keeping your constitute's roots up out of the puddle.

*Gravel comes in handy when sitting a plant inside a decorative planter.* (Adobe Stock)

Gravel in Not-Draining Pots

The best type of flower pot has drainage holes in the bottom, and you should always shop for pots that drain. Merely for pots that don't have holes, some people put gravel in the bottom of the pot, to create a sort of internal "drainage tray" to collect h2o under the dirt. Some people are able to get this to work, simply it tin cause problems, including:

Overwatering: You can't meet the gravel, so how do you know how much h2o is downward there? If water builds up, the soil will turn into a soggy mess, and your institute will be on the fast runway to root rot.

Poor Growth: H2o, nutrients, and air motion through soil using capillary activity, sort of like a straw. If you plug the bottom of a harbinger, it stops working, and when yous plug upwards the lesser of your constitute's soil (by trapping it in a not-draining pot), it stops working, too.

Disease: If y'all've ever opened a container that's been in your refrigerator too long, you've learned immediate what happens when moisture and organic material are trapped in a space with no air menstruum. A moldy mess!

Further Information

Potted Seedling Humidity Helper (video)
Flower Containers for Beginners (commodity)
Choosing a Container for Planting (University of Illinois Extension)