I have a hibiscus in a pot I bring in each winter because it's not a hardy type. I've had it at least 5 years and some years it blooms and some it doesn't. This year it doesn't even appear to be getting any buds. Since the blooms seem to be hit or miss, I didn't trim it last fall when I brought it in thinking maybe I was trimming it incorrectly. Anyone know how to make it bloom? It's an absolutely gorgeous foliage bush, but I want blooms.
I assume it's a tropical (Hibiscus rosa-sinensis)? And does it look healthy (leaves nice & green, no bugs, etc)? Assuming it's healthy, the two first things I would look at are how much sun it's getting, and how you're fertilizing it.
Tropical hibiscus need a decent amount of sun & heat to bloom well, so if you've got it in an area that's too shady that could be why it only blooms sporadically (although with the heat--I've found if we have extended periods of high temperatures they will also not bloom as well...mine do best when we are warm (90's) rather than super hot (100+).
On the fertilizer side, too much nitrogen can stimulate lots of green growth at the expense of blooms, and hibiscus don't like a lot of phosphorus so if you've been feeding it with a "bloom booster" type of fertilizer that can actually have the opposite effect. Trimming it shouldn't matter, they bloom on new wood so if you trim it before bringing it inside in the fall that shouldn't hurt its chances of blooming the following year.
ecrane3 - yes, it's a tropical. It gets plenty of sun, but our temp has been over 100 for 10 days now AND it's sitting on concrete by my pool, so that could be part of it. BUT I had no idea about the "bloom booster" type of fertilizer having the opposite affect and was using that trying to force blooms. So what should we be feeding our tropical hibs?
You can buy special hibiscus fertilizer from some of the retailers that sell tropicals, but if you don't want to do that, just look at the ratio of N-P-K that's here and try to find a regular fertilizer that has a similar ratio. This one for example is 17-5-24 http://www.hiddenvalleynaturearts.com/acatalog/fertilizer.htm Don't worry about matching the numbers exactly, the principle to follow is the middle number being much lower than the other two.