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Firstly, don’t panic. Your plant’s roots coming out of the soil is NOT a big deal, and even if it were, there’s probably an easy fix.
Some plant roots just naturally come out of the soil.
Take Phalaenopsis orchids – all of their roots are technically aerial roots.
Their primary function is different to that of subterranean roots because they’re looking for something to grip onto to secure themselves. Their roots go in every direction, so if your orchid looks a little wild, don’t worry, it’s supposed to. They don’t actually need soil at all.
Your plant needs repotting
This is the primary reason that roots begin to grow out of the soil. There’s nowhere else for them to go, so they start popping out of the top.
Interestingly, not all plants do this. only a couple of my plants do this – my two rubber plants and my Schefflera. I have no idea why.
The only thing I can think of is that perhaps Schefflera/rubber plant roots prefer to either dry out a bit OR (more likely) like a bit of warmth.
Aroid roots don’t particularly care about light or heat – they just crave water.
When it comes to aroids, the roots just grow out of the drainage holes. In general, aroid roots are more pliable and are happy to squeeze between the nonexistent gap between the inner and outer pots. However, Rubber plant roots in particular get really woody as they age.
All you have to do is move the plant into a bigger pot and add some fresh soil. It’s up to you whether you agitate their roots or not – I don’t – just moisten the new soil and the roots will grow into it.
If there are still roots popping up above the soil, you may just have a weird plant
The soil is too dense
Another reason that you have roots popping up above the surface is that the soil is too dense for the roots to grow into.
Again, this depends on the plant, but in general, roots like to follow the path of least resistance. If the soil at the bottom of the pot is a solid lump of clay then it’s easier for them to grow out of the top, even if that’s not their preference.
If the soil is so dense that the plant is choosing to send roots out into the big wide world rather than into the safety of the substrate, then I'd consider either getting rid of the old soil or adding a TONNE of amendments to it.
Also, rehydrate it.
You’re not watering deeply enough
House plant enthusiasts seem to have frightened themselves into underwatering because they’re constantly bombarded with memes about the dangers of overwatering.
When it is time to water, we need to make sure that the substrate is evenly wet all the way through, so the roots will grow evenly through the soil. If you don’t, the roots may prefer to grow out of the soil, rather than into it.
NB just because you evenly moisten the soil doesn’t mean the roots will grow nicely. Sometimes (read:often) house plant roots will grow vertically down through the soil and out of the drainage holes, for no reason other than that they can.
It’s a pain, and I used to painstakingly rearrange them into the pot but now I just leave them to their own devices.
The surface your plant is on is too hot
To be honest, this is unlikely to be something that affects me, BUT it can happen. All my surfaces are white or wood so don't really absorb heat, but if you have steel furniture that gets pretty hot, it can end up heating your substrate and making it a pretty inhospitable environment.
There are a couple of reasons this happens. The first is that it’s just…too hot, but also if the substrate is too hot, then it’s likely to be pretty dry too. So dry, in fact, that the roots would prefer to grow out of the pot.
Subterranean roots like to grow underground. Not only is it the best way for them to get moisture and nutrients, but it keeps them protected from the elements and predators.
However, at a certain temperature, the roots would prefer to take their chances on the outside and will grow out of the top of the pot.
The way I’m writing about this makes roots sound a lot more autonomous than they actually are, but you get the point. Once the substrate is too hot/dry for the roots, they’ll start to grow away from the heat, and back towards the plant.
if you suspect that your plant's roots are growing out of the top of the pot because it's too hot, then I highly recommend you move your plant, or at least put a barrier between the pot and the hot surface OR cover the window with a sheer curtain to block out some of the rays.
If the surface is so hot that your roots have done a detour, then it’s highly likely your plant’s leaves are going to suffer at some point, if they haven’t already.
Your plant is an epiphyte
I mentioned this at the start but I’m gonna mention it again because a lot of people asking why roots are coming out of the top of the soil are asking about orchids.
And the answer is that…that’s how they grow.
The roots don’t grow down towards the moisture like other roots, they spread out all around the plant so they can anchor it more securely.
Not all orchids are epiphytes. The orchid family is the second biggest of the plant families, and orchids grow in a tonne of different ways but the Phalaenopsis is one of the most common orchids you'd buy as a house plant, and their roots grow wild.
So wild, in fact, that the fake ones even have fake roots coming out of the top of the soil.
I actually keep my orchids bare root, so there’s no soil or water or bark or anything, and can confirm – the roots grow however they like. I started it in a narrow-ish-necked vase and quickly had to switch it to a kilner jar.
Other epiphytes, like Hoya, are less inclined to grow this way.
I have no idea why.
They might be one of those quirks of nature that are equally happy growing in soil (completely different to how they grow in the wild) as they are growing on a tree.
That being said, they can be very fussy about being repotted - I repot shallower rooted plants very infrequently because they really don't like the fuss and upheaval and...they don't really need it.
Don’t worry if your house plant’s roots are coming out of the top of the soil. There are several reasons it might be doing this but all of them are easy to fix and are unlikely to cause long-term issues.