Indoor Barrel Cacti: Light Exposure?
Hi! I have been contemplating whether or not a southern window exposure is good enough for indoor barrel cacti grown here in the Midwest. Light intensity is far lower here than in the Southwest. Thus, I am concerned that my barrel cacti may not be receiving suffient light.
My cacti are all within a foot of my south-facing window, and I rotate each plant 180 degrees once each day. On average, I would say they get about four hours of direct sunlight, and the rest of the time it's only reflected light (from the lawn, trees, etc.) that is half the intensity of our direct sun. In my view, this is not enough, since all of the cacti are getting half of the amount of sunlight they could be getting (since only about half of each plant's surface is exposed during the day). Also, I just hope to get them enough light to grow healthily, not worrying about flowering.
I would love to grow them outside, but they get heavily infested with spider mites, scale, etc., even within a couple hours believe it or not.
I would love to know if the current amount of sunlight is sufficient. If not, could anyone recommend an effective pest repellant for plants?