Obviously, the plants don’t know about calendar dates and the earth’s axis so they tend to be governed by the weather and temperatures and flower when they feel the time is right. We can have a certain amount of surety that in the spring months the temperatures will warm up (though it has been known to snow in May!). At this time some plants will begin to flower, taking advantage of early pollinating insects and beginning the process of reproducing.
One of the most brilliant things about geraniums is how they will generally grow anywhere. There are of course always a few exceptions and some will have more particular requirements.
Being as some geraniums will have a short seasonal flowering period, such as spring or summer and some will go nearly all year long, it really depends on the individual plant and the weather. The reason I mention the weather is that if it is particularly hot or dry this will be more gruelling for all your garden plants and will take its toll on the plants vigour and therefore reduce the flowering period.
