What is LECA?

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I’m going to start by explaining my choice to not capitalise Leca. Er, I don’t want to, and it looks a bit aggressive. That’s it really.

If you’re wondering why I’ve suddenly starting banging on about leca and semi-hydro etc etc recently, it’s because I started getting into it during the summer when I was inundated with thrips and I thought it’d get rid if them (it won’t).

Unfortunately, I didn’t get as far as I’d like in my journey because the UK government introduced the Eat Out to Help Out scheme so I was usddenly VERY busy and came down with a ‘mysterious’ illness. It was covid, but I didn’t know it was covid.

My symptoms were just feeling very run down and breathless – no temperature, cough, or lack of taste/smell. I did have blotchy toes though, which I now know is a sign of covid. Luckily, I wear a mask at work and my work was fastidious about handwashing and sanitising. Phew.

ANYWAY.

This is about leca, or growing house plants in a semi-hydroponic system.

What is LECA?

Leca is little pebbles. Instead of soil, you plant your plant in pebbles. Yes, they roll all over the floor BUT you can pick them up easily.

Whilst there are different grades and qualities of leca, it seems to be a matter of personal preference – no more having to mix half a dozen ingredients together to make glorified dirt.

Rather than watering your plant until water runs out of the bottom, you keep your plant and the leca in a net or nursery pot, and keep that in a cachepot (finally a use for all of those planters that don’t have holes!)

What does leca mean?

Leca is an acronym, standing for Lightweight Expanded Clay Aggregate. Basically, it’s clay pebbles that have been heated (I’m guessing that’s when they expand). They’re light because they’re porous, which makes them great fr absorbing water.

How do you convert plants from soil to leca?

This really deserves a whole post of its own and this article goes into it a bit, but in a very small nutshell:

  1. Wash your leca
  2. Wash all the soil off your roots. As much as possible. This is the hardest bit for me, because I’m lazy.
  3. Put the plant in the leca. you want the roots to end about two thirds of the way down the leca, so the bottom third of the leca is rootless
  4. Water the plant by filling the bottom third of the pot with leca. We don’t want to roots to sit in the water until the plant has developed water roots (which are white and fuzzy)
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Why use Leca rather than soil?

I have whole article of whether leca is better than soil, and there isn’t really a concrete answer. There are pros and cons to both.

I’ve enjoyed transitioning a few of my plants, and I intend to continue my quest next year but that’s because I’m a bit of a nerd that loves that kind of stuff. Bear in mind that this is part of my job, so I can justify wasting spending a lot of my time messing about with my plants.

If you like mixing up soil, like repotting, and are generally happy with your plant care, you’re not missing out on anything spectacular with leca.

However, if you like a challenge, and have a lot of plants that you’d really like to get on some kind of schedule, then consider switching to semi-hydro. You can’t really overwater them once they’re established, so you can pick a day of the week and get all of your watering out of the way in one day. That’s one of the things that drew me in.

Oh, and if you’re battling against hordes of fungus gnats, leca may be worth a try, since fungus gnats will struggle to lay eggs in leca.

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Does leca absorb water?

Yes, this is why it’s great for growing plants in semi hydro. Having your plants in leca is kind of like bottom watering your plants – but all the time. The leca wicks up the water from the reservoir of in the cachepot and allows your plant’s roots to absorb it.

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How come plants in leca/hydroponic systems don’t get root rot?

Root rot is caused by a couple of things: lack of oxygen and bacteria. Whilst bacteria can be a problem, the gaps between the pebbles allow for a lot of air flow, so plants get more oxygen than if they were in soil.

One of the fundamental changes plants go through when you switch them to leca is that they shed their soil roots, and grow new white, fuzzy water roots – specially adapted to get oxygen out of water.

(This is why it’s possible to grow plants in just water – read how here – but you need to vigilant about changing the water, otherwise your plant won’t get enough oxygen and the roots may rot).

Root rot caused by bacteria can also be an issue with switching to leca, if (like me) you’re not great at getting the soil off the roots.

I like to keep my plants in plain water for a few days – not only does it get the ball rolling on the plant growing water roots, but it softens the caked-on soil and makes it easier to remove.

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How do you water leca?

This is the great thing about leca. Rather than having to wait for your plant to tell you when it’s thirsty, you can just keep the water reservoir topped up.

It can be annoying when you set an hour or two aside to water your plants, only to find a that a significant proportion of them aren’t *quite* ready, and only will be on the days when you have to work a 14 hour shift.

With leca, that’s not an issue. You can top up the water resrvoir whenever’s convenient. Maintenance is pretty simple in my experience – it’s the transitioning that’s the tricky part.

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Do you need to soak leca?

I don’t, but many people recommend it.

Whilst using soaked leca won’t harm a lot of plants, there are some that would really pretty to start off in dry leca – especially more succulent plants like hoya.

I don’t soak my leca, but I do wash it thoroughly. I put it in a colander , take it outside, and blast it with the hose. Try not to rinse dirty leca water down the sink – your pipes will not thank you.

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My experience with leca

My experience with leca has been pretty good so far. I’ve mainly experimented with pothos and syngonium and they’re doing well. I have a couple of maranta that I switched over in a last-dicth effort to rid them of thrips and it kind of worked…but they’re not looking so hot.

In fact, one of them lost all it’s leaves, but new growth is coming in, so fingers crossed.

I also, bizarrely have my *dead* Fiddle-leaf fig in leca at the moment. I don’t know why. Leca’s many sterling qualities do NOT include ‘bringing plants back from the dead’ but I live in hope.

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Final thoughts on leca

I’ve enjoyed learning about leca and all the nutrients and pH and crap like that, but it’s not something that’s necessary to do (unless the fungus gnats are really that bad). Still, it’s fun, and it’s got me quite excited about learning to grow veggies in semi-hydro/hydro set ups. I’m gonna get me an aerogarden and become self-sufficient.

Feel free to leave any leca-related questions (or any questions tbh) in the comments below, and I’ll get back to you as soon as I can.

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