Overwintering Cacti in apartments

(Question)

Next winter I would like to overwinter my cacti so that I can induce blooming for next year. I live in an apartment so I cannot bring the temperature down to what is required for the winter dormancy. Are there any tips that anyone can give to replicate this dormancy and have the possibility of blooms next spring?

(Answer)

Thank you for contacting Toronto Master Gardeners for advice in getting your cactus to bloom.

Cacti fall into 2 major categories – desert cacti and jungle/forest cacti.  You do not indicate which you are trying to get to bloom so both are included in this answer.

An example of a jungle/forest cactus would be the one commonly known as a Christmas cactus.  This cactus needs a dormant period of about 6 to 8 weeks or until buds begin to form.  During this time, watering is reduced; the plant is not fed; it is subjected to 12-14 hours of darkness each day and cool temperatures of about 12C.  The dormant period should begin in October.  Once buds form, the plant can be moved to a location with bright, indirect sunlight.  Flowers can take up 12 weeks to appear after the buds have formed.

Desert cacti include Mammillaria, Opuntia, Cereus and Echinocactus among others.  They originated in desert conditions where they had bright sunshine.  As houseplants, they need these bright sunny conditions in order to thrive.  They also need a dormant period if they are to bloom.  During the dormant period, which should begin in the fall, eliminate feeding and reduce watering to the point that the plant almost begins to shrivel.  Continue to give the plant a very sunny location at same time as giving it cooler temperatures (12-13C).

You will be challenged to give your cactus the conditions that it requires to bloom.  Not only can you not control the temperature in your apartment, our winter light conditions are not optimal.  Light can be supplemented through the use of artificial lights.  Try placing your potted cactus on a windowsill where the air may be cooler and away from any heat source.

Some cacti do not bloom until they reach a certain stage of maturity.  However, if your cactus was in bloom when you purchased it, it obviously is mature enough.

You might be interested in the Toronto Master Gardeners Guide on cacti.  Click here.