Water: Simply- when watering, you want to emulate what happens in your cactus' natural habitat. Usually an arid desert, but sometimes you may have a jungle species.
When rain does occur, it comes down heavily for a day or so and then does not rain again for many days, months or even years in some extreme locations.
Cacti enter dormant season - water once every two months.
Make absolutely sure soil is dry before watering. Dip your finger down into the soil to the second knuckle- if you feel any moisture hold off for a week.
*Make sure you thoroughly water when you do water.
Cacti enter growing season - water once every two to three weeks.
If you've begun fertilizer treatment- fertilize with quality product every five to six weeks. Not too much!
*Make sure you thoroughly water when you do water. With proper soil drainage you should see a considerable amount flowing out of the drainage holes at the bottom of the pot.
Cacti enter summer season - water once every two to three weeks.
Hold off on the fertilizer! These babies are laying off the growth as their habitat heats up.
*It’s always recommended to do a quick Google search of your specific cacti to educate yourself with their exact needs including water and sunlight preferences.
Light: Sunlight is absolutely essential for all cacti and again- you want to do your best to emulate the conditions in your cacti’s natural habitat.
As a general rule- it’s always best to put your cacti in the most well lit location possible.
It’s almost impossible for a cactus to get too much light in an indoor environment.
Most of these bad boys are evolved to be a-ok in the harshest of desert sun with absolutely no shade. Bringing them indoors shortens their daily in-sun duration as well as direct intensity as a pane of glass is now present between the sun and the specimen itself.
Placement of cacti can slightly alter these directions. If specimen is in strongest direct southwest light soil will naturally dry quicker than if specimen is placed in a less lit or hot location.
Rotation is also an extremely important task to keep each cactus healthy. Rotate your cacti every two to three weeks to make sure they get an even amount of sun and shade. Uneven light can cause serious issues over time- yellowing, bleaching or a general off-color appearance can be a cause of uneven lighting conditions. Take care to prevent yellowing and discolor due to under-lit conditions as well as bleaching and scarring due to excess heat and direct light on only one area of the cactus.
Etiolation is a concern with bringing cacti indoors and subsequently receiving too little light. Essentially, the appendages of the plant grow unhealthily and in an awkwardly uncharacteristic way to ‘grab’ the sunlight it’s not receiving. This is usually a last-ditch effort to find adequate light before finally dying.
Alternatively, if transitioning a cactus from a lower or inadequate lighting condition it’s best to transition slowly as it will be prone to scorching and scarring.
*It’s always recommended to do a quick Google search of your specific species to educate yourself with their exact needs including water and sunlight preferences.