There are a few reasons why your Monstera is growing lighter green leaves than usual, these three being the main ones:
- New leaves actually emerge lime green and darken with age
- Pest damage can leach colour from the leaves (particularly thrips)
- Your Monstera has a nutritional deficiency
If your plant has yellow leaves, I have an article on that here, and for those of you with leaves with brown or black spots, click here.
New growth on Monstera tends to be light green
When Monstera leaves are newly emerged, they’re lighter in colour than the rest of the plant. That’s the natural colour of the plant’s new growth – a vibrant lime green.
The reasons for this are fairly dull:
1. Young leaves (leaflets, if you will) are still developing their chloroplasts. Chloroplasts are the part of the plant that contain chlorophyll (the stuff that makes plants green). As they develop, the plant gets greener.
2. Young leaves are thinner, so they don’t have as many layers (and therefore as much chlorophyll) as older leaves. Light is also better able to pass through them and make them seem even lighter.
As your Monstera leaf ages, it should start to harden and darken to a deeper green. If it doesn’t, then you may have a problem with your plant.
How long does it take for new Monstera growth to turn green?
It varies, probably depending on how fast your plant is growing overall. If you’re after tips on how to get your plant to grow faster, check out this article.
In general, it takes a couple of weeks for a fully unfurled leaf to harden off. Try not to touch the leaves too much in this time. Even the lightest touch can damage them.
Not a lot, but the damage you inflicted to your poor, defenceless plant will always stick out like a sore thumb to you.
Trust me – I manhandle most of my new leaves. They have marks. Do as I say, not as I do.
What if new Monstera leaves don’t darken?
If the leaves aren’t getting darker after a few weeks, then that can be an indication that your plant isn’t happy.
I would always check for pest damage before running to the fertiliser.
It’s surprising how similar thrips damage and chlorosis (lack of chlorophyll) can look.
Thrips damage tends to be concentrated more in one area, and looks like someone has tried to remove the green of the leaves with an eraser.
Side by side, I can see differences in the two forms of damage, but they looked similar enough to fool me (not hard though).
Get yourself a magnifying glass and check for thrips. They look like grains of rice – the larvae are pale green and the adults are fast moving and come in various shades.
Thrips are a pain because they’re so tenacious – getting rid of them is really difficult.
I always assume I have some somewhere.
Thrips seem to particularly love aroids – especially Monstera, but I have found that you can have a few thrips on a Monstera and not have them do it too much damage. I always wipe them off and clean my plants regularly, but I don’t panic if I see them.
They hide in the veins of your plant, which is why the damage looks like it radiates out from the middle of the leaf. it can almost make it look likes it’s meant to be there,
It ain’t.
By the way, thrips are particularly attracted to any damage on your plant – don’t touch those baby leaves! But if you’re hunting for them, check any ripped or damaged sections first.
I have a few articles on getting rid of house plant pests – a specific one on thrips here, and a more general house plant pest routine here.
The key to getting rid of house plant pests is consistency, and keeping up with the treatment for WEEKS. Keep checking, even after you’re sure they’re all gone.
My Monstera adansonii (the plant in the photo on the left) had thrips for a bit which is why I didn’t consider chlorosis. And then it kept producing these mottled leaves despite very few thrips, which stopped when I fertilised it.
I have a whole post on fertilising plants here, but I use a seaweed fertiliser, diluted to half the recommended strength*. I water first with clean water, and then again with the fertiliser water.
Watering damp soil reduces the chance of root burn.
The reason I prefer to assume that its pest damage rather than chlorosis, is that fertilising can wait. But by the time you’ve fertilised your plants and waited to see if there’s any change an infestation could be brewing.
*Ok, I don’t measure. At all. I just put a teeny tiny drop in a teapot full of water.
What is chlorosis and why does it turn leaves light green/yellow?
Chlorosis occurs when a plant isn’t producing enough chlorophyll, resulting in less green leaves.
It’s generally a result of a lack of nutrition – in house plants at least.
Lack of nutrition can be caused by:
- Root rot, since the root can’t absorb nutrients properly
- Being root bound, since there can be too many roots and not enough soil
- Depleted soil – which is why we add fertiliser
- No fertiliser in semi-hydroponic set ups – I use these nutrients for my semi-hydro plants, though many people swear by just rainwater or aquarium water.
You may prefer to add some nutrients to the soil in the form of worm castings, which last longer than water in fertilisers, but I’d advise against DIY fertilisers.
Your plants will probably LOVE banana peels and egg shells but so will fungus gnats! Like I said, I use a seaweed fertiliser, but any house plant fertiliser will do.
Can I get light green leaves to turn darker?
If the leaf is light green because it’s new, then sure. It’ll darker by itself over time.
Thrips damage is (in my experience at least) irreversible. It doesn’t appear to affect the lifespan of the leaf though, so don’t panic too much. Just think of them as battle scars.
As to whether chlorotic leaves will turn green again…the juries out.
Rumour has it that if you’re quick enough, they can green up again, but that didn’t happen to me. Well, maybe one new leaf got greener, but there are some signs of chlorosis remaining.
I also found that the leaves quickly turned yellow and died.
This makes sense – leaves that don’t have as much chlorophyll can’t photosynthesise as much, and are therefore of less use to the plant. If the plant is ready to drop a leaf it’ll drop one that isn’t pulling its weight photosynthesis-wise.
In terms of the overall health of the plant, I think it’s fine.
The roots are healthy and it’s growing quickly, it may need to be chopped and propped to get rid of the bare bottom (lolololololol) stems, but that’s hardly the end of the world.
Final thoughts
I’m a pretty lazy plant parent, and there are many plants in my collection that haven’t been fertilised at all this year. I was hoping (based on nothing) that fertilising was a kind of optional extra.
And it kind of is.
In plants that are growing happily.
The important thing is to be quick off the mark if plants aren’t growing happily, which I *kinda* was.
I’m also very suspicious all the time that there are thrips. Because most of the time there are.
