Algae and LECA: Is It Harmful?

You’ll probably notice some algae once you’ve had a plant in LECA with a clear vessel. It’s that pesky green coating. The good news is that algae is seldom harmful to your plant. But it can be visually unappealing, and there are a few things you can do to prevent it.

The easiest answer is; don’t use clear jars. It sounds obvious, but it’s the only surefire way to prevent it. The cache pot method should prevent algae growth, assuming the outside pot is not clear. Since I’m someone who loves using clear vessels, I’ve had to learn to embrace the algae. There are a few things that I do to help deal with it.

Firstly, repot it once it gets bad; I had a Paraiso Verde in a glass cup that ended up with a thick coating of green slime along the whole vessel; even once I repotted it, the algae was so bad it was stuck on the roots.

As you can see in the pic below, the algae is still all over the roots even though it’s been repotted.

plant in leca with algae

In the future, I plan to not wait as long to repot it if algae is really building up. That being said, constantly repotting isn’t great for your plants either. I’ll generally let the algae build up in smaller vessels and wait until the plant needs to be upgraded to deal with it.

I also tend to mostly use clear vessels for smaller plants, which outgrow their containers quicker and need to be upgraded sooner. This is the easiest way to prevent it, in my experience.

My peace lily is the only plant I have in a large clear container (actually a trash can off Amazon, which works flawlessly). I just ended up putting it on a bottom shelf so you don’t see the algae buildup as much.

Ensure you are cleaning your LECA between repots; it helps kill the algae and delay more buildup and is also just a good practice in general. I got into detail about how I wash my LECA here. Also, I’ve noticed that direct sunlight or very high-powered grow lights promote algae growth. Remember that low-light plants will have less buildup in transparent vessels.

Some people use hydrogen peroxide to try and manage the algae, which does work. I will generally do this if I notice it getting bad but don’t want to change its vessel right away. Hydrogen peroxide is generally good for your plants anyways, it increases oxygen.

I have cut off some of the algae covered roots when repotting on occasion, though I generally don’t. I tend to leave healthy roots alone if possible, but it can be done if necessary.

I did try adding some AlgeaFix, which is a product to control algae build up in fish tanks, as an experiment. It did nothing noticeable, but didn’t hurt my plant either.

Overall, I tend to embrace the algae in my smaller clear vessels, but avoiding clear vessels might be the best idea if it bothers you cosmetically.

Feel free to message or DM me with questions. Love to talk all things plant and will gladly help you on your plant journey.

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