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?

Thanks!

BINGO

Ml2u answered it succinctly but completely. These need to be outside / inside a solarium which gets sun all day (if they had to be, which in your case they don't). If there's something about your environment which prohibits having Feros outside all day in their growth season (now), isn't there a way to combat it? Your present growing conditions are fairly well unsuitable for this genus of cactus.

Artificial lighting is unfortunately just too expensive to rig up, but that would work, I assume.

I'm getting the feeling that trying to grow healthy Ferocacti and Echinocacti indoors, in Wisconsin, without supplemental lighting is just a little too much to bite off. Oh well, I guess my choice of cacti are poor companions with the Wisconsin environment. After all, they are meant to be grown in the Southwest! :)

Thank you for your help.

This is FL signing off. :)