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Why Soil Drainage Is Important
Effects of Poor Soil Drainage
How to Improve Soil Drainage
If you’ve given your houseplants everything they need to survive and you still can’t seem to keep them alive, there is one key thing you may be missing: proper soil drainage. Although water and soil are both essential when it comes to keeping your greenery healthy, failing to provide a way for the water to escape can lead to root rot and even death. Everything from the type of containers you use to the amendments you add to your soil can contribute to how successful your plant’s drainage system is.
Related: The Best—and Worst—Times to Water Indoor and Outdoor Plants, According to Gardening Experts
Why Plants Need Proper Soil Drainage
Proper drainage in potted plants contributes to their longevity. Now growers know that when plants breathe through their leaves, they inhale carbon dioxide and exhale oxygen. “What many people decide know is that the roots of a plant must be able to perform the same process,” says Josh Brown, owner of Predatory Plants. “Waterlogged soil without proper drainage effectively smothers the roots and prevents them from breathing.”
When the soil becomes waterlogged, the air spaces in the dirt become filled with water instead of oxygen. “These oxygen-filled spaces are needed for the roots to function and absorb water and nutrients from the soil,” says Melinda Myers, a gardening expert.
Effects of Poor Soil Drainage
Several things can go wrong when soil becomes waterlogged and a plant’s roots can’t take in oxygen. “Oftentimes in containers with poor drainage or no drainage, there can be a build up of water and salts—which are excess nutrients and minerals in the water or left over in fertilizer—that can cause stress on the plant,” Brown says.
This can cause root rot (one of the most common side effects of improper drainage), which most commonly results in yellow or brown leaves. Additionally, when the soil gets too wet, it becomes susceptible to fungus and can attract harmful insects.
How to Improve Soil Drainage in Potted Plants
If you’ve noticed signs of root rot in your houseplants and believe it’s due to improper soil drainage, there are a few simple ways to remedy the common issue.
Use Pots With a Drainage Hole
When you water your plants, some excess water should come out of the bottom of your container. If that’s not happening, it’s likely your vessel doesn’t have a drainage hole. “Most clay, terra-cotta, or stone materials are usually prepared with a drainage hole when baked for curing,” says Adrienne R. Roethling, the director of curation and mission delivery at Paul J. Ciener Botanical Garden. She adds that plastic pots sometimes come with a stamped hole that has to be knocked out using a screwdriver or a hammer.
For pots without drainage holes, Roethling recommends drilling a hole in the bottom using a proper drill bit or looking for an alternate vessel altogether.
Add Amendments to Your Soil
Adding a chunky bark or a more porous material to your potting mix will help keep the roots from sitting in water. When looking for amendments to add to your soil, Brown recommends using shredded bark, peat moss, perlite, or long-fiber sphagnum moss.
Shredded bark: A mix of shredded tree fibers that have been ground down, shredded bark ranges in size from chunky to fine. It is commonly used to grow potted plants.
Peat moss: A soil amendment harvested from peat bogs, peat moss retains water and helps provide moisture to roots between waterings. “One thing to note is that peat moss becomes hydrophobic when it gets too dry, so be careful to make sure the media containing peat stays moist,” Brown says.
Perlite: A white, unstructured volcanic rock, Roethling says perlite is a better option for drainage because of its irregular shape. Additionally, perlite is porous, which is good for air flow and helps water move through and out of the soil.
Long-fiber sphagnum moss: Like peat moss, Brown says sphagnum moss is often used for water retention in soil. Its looser texture prevents soil compaction and is great for growing tropical plants.
Repot Your Plants
Another way to prevent your plants from getting waterlogged is by repotting them annually. Start by emptying all of the contents out of the container, then loosen the roots and use a ground fork to release the soil, as well. “Place the plant back in the pot and tease the loosened soil around the roots,” says Roethling. “Use your fingers. Do not compact the soils with your palms or fists.”