Why indoor plants keep dying, and how to stop it

December 27, 2024

If you have killed a few, you are in extremely normal company, and it is almost never because you neglected it. Most indoor plants that die are killed by attention rather than by the lack of it. Here are the four things that actually do it, roughly in the order they do it.

1. Too much water, which looks exactly like too little

This is the big one and it is cruel, because a drowning plant and a thirsty plant look the same from the outside. Both droop. Both go yellow at the bottom. So you see a droopy plant, you water it, and you finish the job.

The difference is in the soil. Roots need air as well as water, and soil that stays wet has no air in it, so the roots rot and then the plant cannot take up water even though it is sitting in it. That is why an overwatered plant wilts.

What to do instead of guessing: lift the pot. A pot with wet soil in it is noticeably heavier than the same pot dry, and once you have felt the difference twice you will never need a moisture meter. In a small pot, a finger a few centimetres in works as well. If it is damp, walk away.

Most indoor plants would rather be a bit dry than a bit wet, and in winter they want much less than in summer because they are barely growing.

2. Nowhere near enough light

Light drops off far faster indoors than it looks like it does, because your eyes adjust and a light meter does not. A plant sitting on the windowsill and the same plant two metres back into the room are in completely different conditions, even though both spots look bright to you.

Bright indirect light means the plant can see a big patch of open sky without the sun shining directly on it. A useful test is whether you could comfortably read a book there in the middle of the day without turning a lamp on. If you couldn't, neither can the plant.

A plant stretching with long gaps between the leaves and getting leggy is asking for more light. Scorched pale patches mean the opposite.

3. The pot

No drainage hole is the most common mistake in the shop. A lovely ceramic pot with a solid base means the water has nowhere to go and the bottom of the mix stays swampy. The easy fix is to leave the plant in its plastic nursery pot and slip that inside the nice one, then lift it out to water.
Too big a pot kills as well. A small plant in a huge pot is surrounded by wet mix its roots cannot reach for weeks, and that stays wet long enough to rot. Go up one size at a time.
Empty the saucer. A pot standing in water is the same problem as no drainage.

4. The mix

Garden soil in a pot compacts and goes airless, which brings you right back to problem one. A proper potting mix is built to stay open.

Worth knowing when you are buying: a premium potting mix complies with the Australian Standard AS 3743 and the bag will say so, where a bag simply labelled potting mix may not. It is the difference between a mix that holds structure and one that slumps into mud in a few months. For anything that hates wet feet, a snake plant or a ZZ, mixing in some perlite or using a cactus and succulent mix instead is the easy upgrade.

And feed it far less than you think

A plant that has just come home has controlled release fertiliser in its mix already, so leave it for a couple of months. After that, a liquid feed every few weeks through spring and summer, at half the rate on the bottle, and nothing at all over winter. Fertiliser does not fix a sick plant, and a plant that is sick from root rot will be finished off by it.

Shop related products

Brunnings Premium Potting Mix 36L. Complies with AS 3743 and holds its structure rather than slumping.
Brunnings Cactus and Succulent Potting Mix 5L. Free draining, and the right mix for anything that hates wet feet.
Brunnings Perlite 5L. A handful through a standard mix opens it up and keeps air around the roots.
Brunnings Orchid Potting Mix 15L. Coarse and open, for orchids and anything else that wants to breathe.

The rest is in the Brunnings range and the garden centre.

Did you know we also stock pots, saucers and a range of indoor plant foods in the shop that aren't all listed online. Bring a photo of the plant and the spot it lives in and we will work it out with you, or give us a ring on (08) 8536 4333.