Have you checked for pests and diseases?

Maybe the soil is too moist? let it dry out in between waterings.

Don't over fertilize, as it could burn the roots.

Perhaps they are not getting enough sun. You mentioned that they get "several hours" of sun a day. Where I am (farther north than you), geraniums need almost full sun to reach peak bloom. They will bloom with less, but never reach their full potential.

Perhaps you water too much. I can't see anything else that you do that would cause your problem. Geraniums don't like to be kept too wet. Mine have gone bone dry for a couple of days on occasions and still they bloom well.

You say your neighbor ignores hers and it blooms well. If yours have got the same sunlight then the problem has to be over watering. Let them go dry and then soak them completely and then don't water until they are dry again

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Here is a link that might be useful: Dating Sites

You can also Google Geranium care and growing. There may be several issues with your plants, lack of enough sun seems to be one of them.

Honestly with mine even in the hot dry parts of summer I would go two or three days without water on mine. I overwintered a couple baskets this winter and I watered them once every week or two and they bloomed and bloomed all winter. Geraniums don't like a lot of water!