How to Care for a Cactus Indoors

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Cacti can make great indoor plants however they are definitely on the harder side. At markets they are often too cute to pass by, but plant parents often face some difficulty. The main problem is that cacti need lots of sun which is difficult indoors particularly if you don’t have southern facing windows. 50% of sunlight is reflected by the glass of windows (more or less depending on what kind of glass it is), which greatly handicaps windows facing in any other direction. If your cactus doesn’t get enough light it will either not grow or it will start to grow very stretched out. You can always buy grow lights to supplement any light deficiency you might have.

Care Instructions for a Cactus:

 

Note: Desert cacti require more light and less water than jungle cacti.

 

Water

  • Water thoroughly until it runs from the bottom. Let soil fully dry before watering again.
  • Waterings should be consistent during the growing season of spring and summer. As always, consider pot size, soil mixture, humidity, temperature, and airflow before watering. Generally this is not the case, and on average an every other week type of schedule suits most people. For some, during a very hot and dry spell, a cactus may need to be watered once a week or more. Watering should not happen on a fixed schedule, and should take into consideration these many factors.
  • During the winter dormancy, refrain from watering until you see it shrinking or wrinkling – this could be months but might happen sooner with jungle cacti. Misting dormant cacti, or cacti with damaged roots (from repotting) is okay as well if they start to look thirsty

Here is our in-depth post on watering plants. 

 

Sun

  • Full sun – indoor cacti will likely want as much sun as you can give it
  • Southern facing windows

 

Your cacti will love being outside in the summer if you have any outdoor space. You will see them grow much faster than if you leave them inside. However, you will need to gradually move them over, only putting them outside for a couple hours at a time, slowly increasing over the course of about two weeks. Otherwise your cacti can burn (it will start to look singed/brown in large spots on areas facing the sun). This can be tedious, but you will see a large difference in growth. You can also try to shade the cactus, with a shade cloth or something else, and gradually lift the shade over time.

 

Soil

Soil should be loose and airy. Pre-made cacti/succulent potting mixes are widely available – This is my favorite brand. Sometimes I find store-bought mixes can hold too much water. I often recommend adding perlite, pumice, or grit to the soil mix, or making your own mix, just to be safe from overwatering. Here is a custom soil recipe that I recommend:

 

1 part Turface®
1 part compost
1 part coco-coir (add some pine bark for an even looser mix)
2 parts perlite/pumice (better option)

This is what a good cactus soil looks like:

 

As you can see it’s comprised of many large pieces of different things. Small pieces, dust and materials which hold too much water have been sifted out or not been used. The water held in the pores of the pumice, or by the pine is enough for the cactus.

 

Here is our in-depth post on soil. 

 

Pot

  • Clay unglazed pots are usually best unless the plant is very small.
  • Cacti like smaller pots than other plants, so don’t be so quick to pot-up.

 

Fertilizer

  • Use a fertilizer high in phosphorous (higher middle number) if possible. I recommend this one. – It’s organic with lots of great micronutrients, and is less potent than chemical fertilizers, which is better for your cactus, and the environment!
  • Fertilizing is best done at the beginning of the growing season.

 

Temperature & air

  • Temperatures between 40°- 50° F (4.5° – 10° C) are encouraged during the winter for better growth and flowering during the growing season (spring/summer). Putting cacti against a cold window or in an unheated part of the house will suffice.
  • Airflow is very important for staying pest and disease free.

 

Dormancy

  • Dormant season is during fall-winter when temperatures and moisture are low.

Want to learn the basics of indoor gardening? Check out these posts:

Everything You Need to Know About Water

Everything You Need to Know About Light

Everything You Need to Know About Soil

Everything You Need to Know About Fertilizer

Everything You Need to Know About Plant Pots

How to Repot Plants

How to Get Rid of Pests Naturally