LECA DOESN’T Prevent Pests – It Just Makes Them Easier to Deal With

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No, but it can basically eliminate some, and make others easier to manage.

The main reason I started researching switching to a semi-hydroponic system was the thrips on my Thai Constellation. I’m a naturally frugal person that gets stressed and overwhelmed easily, so I couldn’t let my nearly £100 plant die.

I KNOW that a LOT of people pay a lot more than that for plants, but that’s not something I can afford to do currently – more for mental health reasons than financial ones. I also think there’s plenty of awesome, cheap plants, so there’s no need to spend a fortune on them.


I soon learned that leca isn’t the pest elimination system I was hoping it’d be, but there are a few properties it has that mean that once you have the pests, getting rid of them is much easier.

If you’re interested in reading about my house plant pest elimination strategy, read this post. It’s especially good for those of you that don’t want to/can’t use any chemicals on their plants. I mean, you can (I do), but you don’t have to.

Will switching to leca get rid of Fungus gnats?

Fungus gnats don’t really bother me. Since I started bottom watering, I only get a few.

But according to a lot of the house plant Facebook groups I’m in, a LOT of people HATE gnats. If that sounds like you, Leca may be the answer to your prayers.

You see, fungus gnats, aren’t that interested in your plants. They’re after the rotting matter and fungus (hence the name) to feed on. They also need the soil in which to lay their eggs. So if there’s no soil, there’s no gnats. Perfect.

Unfortunately, this is going to mean a lot of work if you have a lot of plants. Transplanting from soil to leca can be a difficult and time-consuming undertaking, and if you want to get rid of all the gnats, you’ll need to get rid of all the soil.

I’m going to generalise a bit here, and say that gnats tend to be a problem for new plant parents. Not always, but that seems to be the trend. They like moisture and damp soil, so overwatering (a common mistake newbies make) can cause them to appear in droves.

But if you have an idea of what you’re doing, have a chronic gnat problem, and are interested in getting started with a new challenge, the leca life may appeal to you.

How about thrips? Can thrips survive in leca?

Ugh, thrips.

I’ve heard accounts from people that switched leca and never saw thrips again, and an equal number of people that say that thrips show up whether you plants are in soil, leca, or whatever.

Whilst I have had thrips on my plants that are in leca (and just water) I do find that they’re a lot easier to get rid of in leca.

The problem I have with thrips is that they’re incredibly persistent. It can take literally months of diligently showering and spraying them with neem oil for them to leave, and then they return once you stop.

In leca, they’re don’t seem to be so…tenacious. Once you’ve eliminated them all, they don’t seem to be so hell-bent on returning, which begs the question, how do you eliminate them?

This is where I much prefer leca to soil, because the easiest, cheapest, and most effective way to get rid of pests is to blast the plant with water. I use my shower. But you run the risk of overwatering if your plant is in soil.

Overwatering isn’t a risk with leca (once it’s fully transitioned, anyway). You can just take the inner pot out, shower away, and put it back in the cache pot.

Even if you don’t have a shower (some people bath, I don’t judge), you could fill the sink with water, take the plant out of the leca and submerge the whole thing. Drown those suckers.

Yes, you’ll have to be careful with the roots, but at least you won’t have soil everywhere.

Spider mites

Spider mites don’t care about leca, as you can see here:

this little Dracaena *was* thriving in leca. I’m confident she’ll shake off her spider mites.

If you look at the newest full leaf, you can see the colour looks like it’s been attacked with an eraser. The new one emerging looks very sad too.

Spider mites lay their eggs on the undersides of leaves (they look like white powder), and they go through their whole lifecycle on the plant’s leaves. They couldn’t give two hoots about the substrate that being used.

So if spider mites are your issue, leca won’t help the initial infestation. Same rules applies with dealing with them once they’ve arrive though. Though I don’t believe a humid environment will deter spider mites, they don’t like getting wet, because it destroys the webs they build.

Unlike real spiders, spider mites don’t construct webs to catch prey. Their prey is our poor, unsuspecting plants. They build them for protection. No webs = exposed mites. I assume it’s protection from predatory bugs, so they probs don’t need the webs anyway, but if they rock up to my plants and start building their webs, I’m not going to stand by and just let them.

I seem to have gone off on a tangent.

Showering off plants is a great way to get rid if spider mites. Having your plants in leca makes it easier to shower off your plants.


Some scale 100% won’t care about leca, and they won’t be deterred by a shower. You’ll have to pick them off.

Thankfully, a few of the more common type of scale insects (like mealybugs) do lay eggs in the soil, and shower off easily, so transferring your plant to leca will make that whole process easier for you.


Pretty much the same as thrips – some people swear by leca, some people don’t notice any difference.

My issue with aphids and leca is that I only get aphids on plants with roots that I can’t clean easily: namely ferns. Luckily, ferns love water, so I transferred them to terracotta pots and shower them as often as I remember to.

Caroline Cocker

Caroline is the founder and writer (and plant keeper) of Planet Houseplant

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