We recommend ZZ Plants to relatively new plant parents because of their easy care requirements. They aren’t as sensitive and delicate than some other plants and still look incredible in every room. However, if you find that your plant is starting to turn a little yellow, this will be your plant telling you that something isn’t quite right. The most common causes of yellow leaves on ZZ Plants are: overwatering, drainage issues, underwatering, too much sunlight, nutrient imbalance and temperature extremes.
Overwatering can cause yellow ZZ leaves
If the leaves on your plant have turned yellow you are most probably overwatering. Another thing to look out for that is caused by overwatering is whether those yellow leaves are starting to drop from the plant.
Overwatering is one of the main plant killers as you might not always be able to tell before it is too late. ZZ Plants don’t like to be sitting in a lot of water for long periods of time as this can lead to root rot meaning the plant becomes unstable and also cannot get needed nutrients from its root system. Waterlogged soil also gives off quite a damp and musty smell so make sure to check this every so often too.
If you think that your plant is waterlogged, check the moisture of the soil immediately and adjust watering accordingly. We also recommend replacing the potting soil straight away (rather than waiting for it to naturally dry out) so that the roots can begin to recover. Cut away the rotten roots and dead leaves so that the plant focuses on regenerating healthy growth. Make sure that you always wear gloves when handling your ZZ Plant as they have calcium oxalate which can cause skin irritation and also stomach pain (if ingested).
A yellow ZZ Plant can also indicate drainage issues
Sometimes it may not be your watering schedule that is causing your plant’s leaves to turn yellow, but the poor draining of the soil and pot. You can very easily increase the amount of drainage by mixing in a small amount of perlite. This will make it far easier for water to flow through and out of the drainage holes of your pots (you should also check to make sure your pots have drainage holes). Another easy step is to add a few small stones or pebbles to the bottom of your pots, this helps in making sure that the drainage holes are never blocked by soil or any loose debris.
Although clay or terracotta pots can be a little bit more expensive or breakable, their upsides are much more than just the aesthetic. The clay they’re made of is permeable which means that some of the water in your soil can evaporate through the sides of the pot. This isn’t the case for the plastic pots that most use, which instead hold in all of that moisture. So sometimes it is worth investing a little more to make sure that the roots of your ZZ Plant are not sitting in too much moisture.
Underwatering might also be causing yellow leaves
If your ZZ Plant’s leaves have turned yellow, dry and crispy (starting from the tips) it may be because you have not given it enough water for a while. Although your plant won’t die on you suddenly if you forget to water it every once or twice, or make it go a little longer without water whilst you are on holiday, consistent underwatering will start to have an impact on your plant’s health. It is important to keep an eye on the moisture levels of the soil so you know when your plant is ready for watering.
Make sure to check the moisture in the soil before you water your ZZ Plant. There are two really easy ways to make sure that it definitely needs water. First check the moisture at the top of the soil, if it is still damp then wait a few days before watering again. You can also lift up your plant carefully to check the weight of the plant before and after watering. You will then start to be able to gauge how heavy the soil is when it is in need of water.
If you find that your plant feels very dry, water it a little every other day for a week. Your first instinct might be to give it loads of water straight away but this can actually be harmful to your plant if the soil goes from one extreme to the other. Yes, plant’s can get shocked too by a sudden change in environment. So instead you want to reintroduce frequent watering for a week or two and this should solve the problem.
Luckily underwatering won’t instantly kill your ZZ Plant so you have time to rectify the problem before it is too late. If you trim away the yellow and dried leaves, any new growth should hopefully be healthy and luscious green!
Yellow leaves can be caused by too much sunlight
Lighting is always important to your houseplants and ZZ Plants are no different. If your plant is getting too much bright light you’ll start to notice yellowy patches throughout the leaf. You may also notice some brown tips on the leaves. This is due to the sunlight burning the leaves which is unfortunately irreversible. Try moving your plant into a slightly shadier place, and if there’s no improvement move it a little further again until you find it’s the perfect spot. You can carefully trim away the burnt yellow and brown leaves so your ZZ Plant can focus its energy on new healthy growth.
Nutrient imbalance can cause some yellowing
ZZ Plants can actually be a little sensitive to fluoride that you find in tap water. Over time, this may be causing harm to the roots which often shows itself in yellow leaves. If you live in a hard water area, it may be that your plant is reacting to high levels of chemicals in the water.
There are a few ways to make sure that the water you give them is free of both these chemicals. Firstly you can leave a jug of tap water for around 24 hours to allow for a lot of the chemicals to evaporate. Another method is leaving a tray outside to collect rainwater to give to your houseplants to make sure chemical levels are lower than the treated water that comes out of your tap. Some plant parents also have a filter system for their houseplant water but we find that the methods above work just as well!
Your ZZ Plant could be in an area where it’s getting a little too much light, or it’s getting too hot. The perfect spot for your plant is just a touch further inside a bright room, potentially an east-facing window if there’s a good spot available.
If you’re not already, make sure to open your windows every now and then to make sure that the air in your room is circulating properly. This reduces the risk of hotspots forming in the room where your ZZ Plant is sat.
It is also important to keep your plant away from AC or heating vents/radiators as these temperature extremes can be very harmful to your plant and result in various issues, including yellowing leaves. The ideal temperature for your plant is between 18°C – 24°C, so it shouldn’t be too difficult to keep in a good range. You can always pick up a digital thermometer to check the spot your ZZ Plant is in.
It could indicate a pest infestation
If you notice yellowing patterns on your ZZ Plant it may be caused by pests, most commonly in this case Aphids. You are more likely to get these if you keep your plant out over summer but they may also become infected in your home so watch out for these. Aphids camouflage themselves well so carefully inspect each leaf if you suspect they are present.
If you do notice Aphids on the leaves, first remove the most infected leaves and dispose of them immediately. Then wipe down the remainder of the plant with a warm soapy cloth whilst wearing gloves.
These are the main reasons why your ZZ Plant is developing yellow leaves. If you have caught the problem early and fix whatever it is that is causing the discoloured leaves, then your plant should return to full health pretty quickly. Be mindful that plants do naturally develop the odd yellow leaf which will drop off every few months, more so in winter. So just keep an eye out for the rate at which the leaves are changing colour and don’t be alarmed if you see the odd one.
Written by Joanna Turner