Why do geranium buds turn brown and not open?

too much water. This will happen if geraniums are planted in an area of little sun, then it rains day after day. Also happens if geraniums are in pots but overwatered. Soil must have spaces for air in order for buds to form & open. An overwatered geranium will show stress first in its extremities, which are the buds. Plant in a sunny location with good drainage. If planting in pots, use clay pots and allow soil to become fairly dry before watering. Geraniums will recover quickly once the soggy soil problem is solved.