Hi all,

so this is a hedge that used to bloom in my parent's garden, not maintained properly by the gardener for a couple of years, and became a mess.

I started trying to bring it back about 4 months ago and cut it back to a bare skeleton. As you can see, it grew very nicely and the leaves are very green and lush. The problem is blooming. After the growth got to the level I wanted, I gave it a break from any fertilizer. Then started using more potassium based fertilizers and also muriate of potash. There were blooms for the first time in almost two years, but the quality, size, and number of blooms aren't back to its former glory just yet.

As can see in the pictures, the blooms are small. Especially the reds which are very tiny. The petals aren't particularly good quality either. Some plants aren't even producing buds, much less blooms. So it's producing blooms again which I'm happy about, but definitely this can't be the end product. Especially since the 2nd to last to the right, has begun blooming with big white blooms.

Location is Trinidad and Tobago. Days avg about 30 Celsius (86f). Nights avg 21C (70f)
Full sun to partial shade (partial shade blooming better)
Soil is between 6.5 to 7ph from beginning to end of hedge.
No pests.
No fungus.
Magnesium sulphate (epsom salt) supplemented.

Do you have fish fertilizer? My hibiscus bloomed like crazy when I used that for them.

As a general research rule, I would check the amount of sunlight, what the weather was like and the nutrients/minerals in the soil if the soil is sandy. A cheap soil test for NPK may be useful if you cannot get a proper soil test done (all you need is to detect whether the NPK levels are too low/high) although it would be nice to also know if other minerals are "off".

You may need to go back to using the fertilizer program that was once used to produce the larger blooms. Some tropical hibiscus also produce smaller blooms when the bush gets very large so again, you may need to tweak the nutrients in that case too. They can also reduce the bloom size due to the environmental conditions (hot and dry; after very heavy rains).

Beautifully done but to me they might be crowded to much. You might want to pot some up and put them
in front of the others with a drip irrigation. Fish fertilizer or a bloom booster might work also.

they have gotten too large for the space, too close together, I would dig them up, divide them, refresh the soil and plant starts back. Also remember that these like regular water and use alot of water to stay lush.