Q&A for How to Care for a Cactus

It's better to underwater your cactus than overwater it. Because they grow naturally in the desert, cacti are hardy and thrive in dry conditions. During the wintertime, you actually don't need to water it at all!

Fortunately, there are many success stories of gardeners rescuing a rotting cactus. You can try doing this by removing all the rotted parts by pruning them away, then initiating a care program to encourage new growth. Tip the plant sideways in its container for 3 days, to allow the cut sections to dry out and heal. Then repot the cactus in fresh cacti soil and either a new container or a fully cleaned old one; position it in the soil only as deep as is needed to keep the cacti upright. Water weekly and keep the cactus in a suitable warm and sunny spot. In a few weeks, it’ll either start returning to normal and grow again or it’ll curl up and be done with. Hopefully it’ll thrive!

If you live where temperatures don’t drop below 5ºC (40ºF), and don’t experience too much moisture, the cactus may be able to cope staying outside. However, if there is a risk of frosts, a likelihood of lots of cold moisture or temperatures fall below 5ºC (40ºF), the cactus should either be under cover or brought indoors. A good time to do this would be before the first frosts appear, or before continuous cold rainfall sets in, so gauge this by what is usual for your area.

A cactus that gets no overhead watering can accumulate both dust and cobwebs over time. While this doesn’t generally harm the cactus, it can be unsightly and isn’t good for indoor cleanliness. To remove webs and dust, use a small paintbrush or similar soft and small brush to gently sweep out the debris from the cactus top and spine areas. Trickier areas might benefit from using a blower brush often used for cleaning camera lenses. Try to do this regularly, to reduce the buildup of fluff on your cactus plant. One last thing: Check that the webs aren't from spider mites; if so, the cactus needs to be treated to remove these pests.

A cactus grown in a container or confined garden space can rot easily when subjected to regular overwatering, especially when the temperature isn’t warm enough to cause excess water to evaporate quickly. Another cause of a rotting cactus is fungal attack, which can be encouraged by overwatering and/or the wrong soil (poor drainage or soil not suited to a cactus). Root rot can occur from both fungal and bacterial invasion. In future, use the right soil for a cactus and take care to water it only every 1 to 3 weeks and only give it enough water to moisten the soil.

Aphids are a nuisance but they’re relatively easy to get rid of––depending on how spiny your cactus is! Use a soap wash (insecticidal soap works well) or an organic aphid spray you can make yourself. Squirt this onto the area where the aphids are. Try to dry the cactus if it seems too wet after the aphids have been dispersed with. Squishing aphids is an option if you can safely access them but the spikes might prevent this. If you have access to ladybug or lacewing beetles, you can use these for organic control as well.

Yes, an old toothbrush and warm, soapy water should do the trick.

Follow the techniques in this article to ensure that it's receiving the best care possible. Some studies have suggested that plants respond well to music, so you could consider playing music for it.

It is recommended that you use a grow light. These can be purchased at your local garden center or off the internet. Just do your research first so you get a good match.

Put onion peels in warm water for 24 hours then spray it in your pot to get rid of them.

It may be a springtail. If so, they are really useful to plants and terrariums because they help by eating dead plants and animals, fertilize soil and can be used as animal food.