Opuntia Microdasys needs more light, but how much?

[ed_zeppelin]

How much light is too much/not enough? I just bought my first cacti last spring. A variety of them and they seem to be doing well for the most part. This one in particular was very healthy until fall came to Oklahoma and I moved them all away from the cold window. Now it has suffered the effects of not enough light. New growth is long and flimsy. A couple of others look a bit droopy, but not much. I would like to gradually give it more light, but I am afraid the heat of a east-facing windowsill will kill my cacti? I really have no other place but this one window or on the opposing wall about 10ft away. I have read that cactus roots will become to hot in a windowsill, so I guess I am concerned that I am wasting my time trying to grow them in what may be less than ideal conditions.

[greenknight]

Opuntias need as much sun as possible. To keep the roots cool you can either use light-colored pots or set the pots inside larger pots, big enough to leave an air space around them.

If they get enough light in the Spring and Summer, that's what matters. Your problem is they've been growing in the Fall and Winter, when they should have been dormant. You need to let them dry out by Fall so they stop growing. Ideally, you'd keep them quite cool and give no water until Spring - growing them indoors you likely will need to give them a little water to keep the roots alive, like a little spritz from a spray bottle once a month or so.

Most cacti can take quite cool conditions when they're dry and dormant, many can stand some frost. There are a few tropical species which need more warmth, but most common cacti do best if kept cool during the dormant season. Opuntias generally are frost-hardy, Opuntia macrodasys fa. alba (the kind with white fuzz) is more tender, though.

[7george]

I have been keeping O. microdasys in similar climate at west-facing windowsill and roots are not a problem if no heating elements are located under that window. They can stay severe drought and first start dropping their dry pads and need 1 - 1.5 year to die if not watered in a pot. But glochids made me quit growing this species further more.

Well, and if you don't have any outdoor summer space for this plant better save it's spot for other cacti.

[greenknight]

Calgary is a long way north of Oklahoma, the sun's not as intense. Opuntias are much happier if the can spend the Summer outdoors, though.