We'll start putting black cloths over our 2,000 poinsettias in the school greenhouses on Monday. This should be started on the Fall Equinox. It takes about four weeks of covering them from late afternoon to late morning to trick them into setting bud.
Don't leave them on all the time! This is what some people do! The trick is to make sure your plants (both the poinsettia and the cactus) have very short time periods of light. The students cover ours before they go home at 2:30p.m.....then they are uncovered at 9:00a.m.. We use huge black cloths on a structure built over each ghse. bench. Actually, the cloth is thick black landscape fabric.
At home, you could achieve the same results from either placing your plant in a closet for those same hours...or putting near a window in an unused room. Both plants require little water...but cannot be neglected completely.
I'll try to get some pics posted of the kids and their plants!.......p
I had them sitting on the half wall by my front garden and a few morings ago I noticed every single one of them was eaten to a single nub sticking out of the pot.