How To Flower...Or Forcing To Flower.

Hi my friends:
I have many Hibiscus plants, some of them as old as 2 years, but not a single flower at all. Anyone knows how to force them to flower?

Many thanks :)

Can you tell us a little more about the conditions you're keeping them in (indoors/outdoors, sun/shade, how much water, how much/what kind of fertilizer)? And do they look healthy otherwise or are their leaves looking sickly, insects munching them, etc?

Hi my friend:
I keep them outside, only 3 hours direct sunlight in 20 gal plastic pots, plenty of water (one day in between), leaves are deep green and pretty healthy, no bugs. I use Vigoro fertilizer, both water soluble (every 2 weeks) and time released (every 3 months). I hope this will help :)

My first suspect would be the amount of light. 3 hrs is not a lot and while many hibiscus probably appreciate a little shade during the hottest part of the day, they may bloom better if you can get them a little more sun.

Second suspect would be the fertilizer--I don't know what's in Vigoro fertilizer, but hibiscus actually prefer ferts with a little less phosphorus than many other plants so if it's got a high middle number that's probably not helping you either. And you might check on whether your total amt of fertilizer is appropriate or not. I only use a time release on mine and they bloom great, and I know if plants get too much nitrogen they'll tend to put out a lot of green growth at the expense of flowers so since you're using the time release plus regular fertilizer every couple weeks that may be too much, I'd probably do one or the other but not both.

My last thought would be the pot size--I don't know how big your plants are but 20 gallon pots are very large and if your 2 yr old plants are about the same size as mine that is way too big of a pot. What happens in that case is the plants spend all their time and energy growing roots to fill up the giant pot instead of blooming, so a smaller pot might get you blooms faster (having a pot that's way too big for a plant also makes it much easier to accidentally overwater--doesn't sound like you are right now since you'd be seeing leaves turn yellow and fall off, but it's definitely something to watch out for)

Thanks a lot for the advice my friend:
One thing I noticed when pruning, they grow back really fast and greener, also lot of leaves. The leaves are totally healthy and BIG. I'll stop using that fertilizer and look for another that encourages flowering if it exist.
Question:
Can I prune the roots so it can fit in a smaller container?

If you need to prune the roots to get it into a smaller container then it doesn't need to be in a smaller container anymore :-) (Although if it was a small plant when you put it in the container, the time it spent growing roots to fill the container could be partly why it's taking so long to bloom)

The fast growth but no flowers does make it feel like you could probably cut back on the fertilizer a bit. I wouldn't necessarily switch though, just cut back (I'd pick either the controlled release or the water soluble, but don't do both. And if you choose the water soluble one, read the directions and make sure you're not giving it more than what the label says). If you do switch, don't go for one of the typical "bloom booster" fertilizers, those have lots of phosphorus which encourages blooms for other plants but makes hibiscus unhappy.

Thanks for all the advices my friend. I will let u know how is my progress.