This Is A Popular Alternative To Soil — But Does It Actually Keep Plants Alive?

Another reason someone might use LECA or another type of pebble is if they want to improve their soil’s drainage. The idea is that placing them at the bottom of a pot (underneath the soil) can help store any excess water and keep it from drowning a plant’s roots.

This technique gets mixed reviews: While some people claim it can help prevent overwatering, others say that it can actually do more harm than good, due to something called the perched water table.

“Basically, there’s a difference in medium between the rocks and the soil, so all the water will saturate at the bottom of the soil instead of settling where the rocks are,” explains plant care expert and chemistry teacher Paul Thompson, M.A. “Now, you’ve moved that level of saturation up higher, to where the roots are.” This can cause water to choke the roots and lead to rot, which is hard to bounce back from.

There is, however, one thing that can basically ensure you won’t overwater your plants, whether you’re using LECA or not: a drainage hole.

When keeping plants indoors, you’ll want to recreate the outdoor environment they’ve adapted to. And, as Thompson reminds us, “in nature, plants can easily get rid of excess water because they have the whole ground. But when you’re talking about a tiny little volume, it’s so important to have that drainage so extra water can drain out.”

Marie Viljoen, the urban gardener, author, and chef behind 66 Square Feet (Plus), agrees, cautioning, “Do not go for a pot without drainage holes. If it doesn’t [have any], drill a hole in it… That’s the No. 1 thing a container needs.”

Drainage holes also provide a visual cue that you’ve given your plant enough water. Once you see it trickling from the bottom of the pot, it’s a sign your soil is moist enough. Without one, it’s impossible to know if your plant is still thirsty—or on the verge of drowning.

Isabelle Palmer, city garden designer and founder of The Balcony Gardener, admits that the few times she’s tried to place plants in decorative pots without drainage holes, they’ve died. “After a while, it just becomes such a moist environment that the roots rot and it kills the plant,” she says. “I would never do that again.”