How to Stop Root Rot In LECA

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One of the main reasons people switch to from soil to semi-hydroponics/LECA is due to the ease of watering.

Working out when to water is difficult enough to work out, but when you have a LOT of plants it becomes a military operation ESPECIALLY if you have to fit all of your plant care into one day.

Obvs plants don’t do the kind thing, which would be to arrange their watering schedule so they all needed watering on the same day.

With leca, you can top up reservoirs whenever you like. I mean, it’s not always ideal – some plants need the shower method, and others may need extra top-ups in summer, or if they’re tiny and growing.

But leca is NOT necessarily an easy way to grow plants, and they can be susceptible to to the same issues as plants in soil. Leca is just another substrate, and it suits some people better than others.

Some of the people it can suit are those that struggle with overwatering because you technically can’t overwater a plant in leca (for the water would overflow and you’d get a wet floor) BUT the bad news is that plants in leca can still get root rot. Overwatering causes root rot, but only because it contributes to an environment that root rot can thrive in – it’s not the direct cause.

Can plants in LECA get root rot?

Yes. The bacteria that cause root rot can still thrive in leca BUT it’s more difficult for it to do so. The great thing about leca is the amount of airflow it allows around plant roots. Root rot bacteria are anaerobic, so thrive in oxygenless environments.

More oxygen = fewer bacteria.

That being said, it can still happen, and I’ll explain how as we go through the various methods of preventing root rot.

If you can understand how root rot flourishes, you can reduce it, and as you get more experienced with switching plants over to semi-hydro you’ll probably find that your root rot rates (say that five times fast) drop over time.

That being said, there are dozens of factors that can influence how leca affects your plants: everything from the health of the plant to the mineral composition of your water, so there’s a certain amount of trial and error here (boo).

If you have a plant you’re particularly attached to, perhaps don’t make it your first foray into leca. I recommend people start by propagating cuttings in leca first so they can get more of a feel for whether it’ll suit their lifestyle, before going to the trouble of moving whole plants over.

How to prevent root rot in LECA

These are not hard and fast rules by the way. Some plants are more than happy to still with their roots in stagnant water, whereas some get root rot overnight. This is just the deal with working with living things.

However, if you stick to these rules if you can, you’ll reduce the chance of getting root rot.

Don’t let the reservoir touch the roots

One of the things that drew me to leca over ‘proper’ hydroponics was the lack of changing the water, or running pumps. The water is held in the leca, and wicked up from the reservoir over time. Aeration comes from the, er, air, rather than a pump.

The general rule is that the water reservoir should be the bottom third of the pot (some people draw a line on the inside of the pot, but most of us just eyeball it) HOWEVER roots grow down over time, so can end up sitting in the water.

Now, this is usually absolutely NOT an issue, because the roots get plenty of oxygen from the middle part of the set up (I shall draw a little diagram)

Even if the roots grow further into the water, they can get plenty of oxygen

However, for whatever reason, sometimes plants that are more prone to root rot can still develop it if the roots grow into the water. It’s not species-specific, it just…happens. Which isn’t really helpful other than to make you feel better.

Keeping the roots out of of the water can be a pain, but you can just trim the roots if you’re lazy (provided it has a decent-sized root system), or take the plant out of the leca and rearrange the roots so that they’re higher in the pot.

Roots grow towards water, so this may become a bit of a chore over time, so there is an alternative option:

Use the shower method for watering

I don’t use the shower method because, for me, it defeats the purpose of using leca. The shower method is basically exactly the same as watering a plant in soil – you water the leca thoroughly, maybe let the water sit for a few minutes, and then remove any excess.

This is a great method if you like to water, for example, every week BUT it can lead to dehydration in summer if it gets super hot, and it’s difficult to tell if the leca is wet or dry when there’s n reservoir.

The shower method is great for organised people that love routine, but terrible for people like me that thrive on routine BUT if that routine is interrupted (because life) then spiral into panic and can barely function as a human.

Clean the roots as well as you can

This is really key. Any soil that’s left on the roots can provide a lovely environment for root rot bacteria to thrive.

It’s not imperative to get off every molecule of soil. There comes a point when the cleaning work you’re doing is more harmful than helpful to the roots.

Plants do have their own defenses against root rot so it’s not a case of dirty roots immediately and definitely causing root rot – it’s more than it increases the chances.

Root rot will take over an unhealthy plant quicker, so bear that in mind. If you’re transitioning a plant because you think it’ll help with root rot or pests then you need to keep an extra close eye on the roots and nip any rot in the bud quickly.

I would recommend rooting any unhealthy plants in water first, just so you can keep a close eye on the roots without having to disturb any new growth.

Maximise air flow

There are a couple of ways of doing this. One is the more obvious option – put the plant near an open window or fan. The other is less obvious but works well.

If you’re using a nursery pot rather than a net pot, poke a load of holes in the sides with a knife (be careful).

Use a small bowl or tray to hold the reservoir, rather than a pot, ideally short enough so that if the cache pot is full to the brim, it only goes a third of the way up the leca. That way, you’re maximising the amount of air that can get through the leca.

here I just used a shallow tupperware as reservoir

Try various additives

Semi-hydroponics is fairly new to mainstream house plant care, so you have to root around in various forums to find this stuff out. Basically there are LOADS of chemicals and potions that you can add to your nutrient water to reduce the chance of root rot.

These vary a LOT – not only the products used, but the amounts used and the combinations. Some people add everything in together, others prefer to cycle different products month by month.

Hydrogen Peroxide

Hydrogen peroxide is a very popular addition to nutrient water, not only because it will kill bacteria, but because it adds oxygen into the water. Hydrogen peroxide is basically water with an extra oxygen atom added. More oxygen is good and can make roots grow faster so can be a great addition even if you don’t have any root rot.

Just be aware that if you expose hydrogen peroxide to light it’ll lose its extra oxygen and you’ll be left with expensive water. If you’re using a glass as an outer pot you can cover it with black paper to keep to stop that oxygen from bailing.

Superthrive

I’m planning a full article on Superthirve because it’s one of those products that a third of the house plant community swear by, a third claim is snake oil, and a third confused people who either don’t use it or use it but don’t really know why.

I like Superthrive. I’m currently experimenting with different propagating methods, and Superthrive in water yielded the second-fastest results (after nutrient water). So it definitely does something.

I don’t recommend lazy people use Superthrive, because it can make the water go a bit…gelatinous, so you need to clean your pots regularly. It’s good for me because it forces me to do it (and this is my job, so I really should be cleaning my pots) but if you’re not gonna, leave the Superthrive out.

Warmth – light – humidity

The key to great plant growth. Improving your warmth, light and humidity helps in two ways, but more or less for the same reason.

They help your plant grow faster, so it will develop a larger root system thats less susceptible to root rot.

Secondly, it’ll grow more healthily, and be better able to fend off bacteria without developing root rot.

How to treat root rot in leca

It’s all well and good going on about how to prevent root rot, but sometimes despite our best efforts, it turns up anyway. Things beyond our control, such as travelling resulting in a bit of neglect, and, er, winter can thwart our best efforts to keep our plants healthy.

So what do you do if your leca plant gets root rot?

Reclean the roots

Dirty roots is most likely the cause of your root rot, especially if it’s a recent transition. Even if you’re pretty sure you cleaned them thoroughly, another quick clean won’t hurt (but be gentle). I have a whole section on cleaning the roots in this article.

Clean the pots/change the water

Bacteria can be pretty resistant so a quick rinse may not suffice. Wash your pots and leca in hot soapy water and rinse well. Just make sure to remove the plant first (though you could dip the roots in tepid soapy water for an extra clean).

Trim any brown mushy roots

Roots that have been infested with rot tend to come apart pretty easily, so I just gently massage the root and remove anything loose. If there are stringy bits left behind I leave those on – sometimes the outer casing of the root comes off as part of the process of switching to soil roots, so I leave the stringy bits.

To be perfectly honest I have no idea if they can reform (probs not) or will just drop off later, but I assume that the plant knows what it’s doing.

Sterilise the plants

Hydrogen peroxide is a great option here, due to its gentle cleansing properties and extra oxygen. Adding it to the water reservoir is a great option too, but you can just soak it for a few minutes (one tablespoon per 250ml of water is a good ratio.

Final thoughts

I’ve transitioned tonnes of plants to leca, and never had a case of root rot that I couldn’t shift with relative ease. In my experience, the most risky time is the transition, so as long as you keep a close eye (or develop water roots in water rather than leca) once you have a decent root system established and keep up with general maintenance, you’re all good.

This is NOT the case with soil – some plants just seem obsessed with rotting (Thai Constellation, I’m talking about you) and won’t stop until you move them into leca or water.

There are a lot of horror stories about leca and root rot (especially pothos, which transition fine for me) but I don’t think it’s any worse than dealing with root rot in soil. It’s actually easier and cheaper, because you can sterilise everything rather than chucking it away.

The actual issue seems to be that people assume that root rot isn’t possible with leca – kind of like how they think that switching to leca will eliminate pests.

This unfortunately isn’t true, but I do think leca is easier to deal with when it comes to troubleshooting problems.

Caroline Cocker

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

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