Geraniums are one of the more popular bedding plants for gardeners. They come in a multitude of colors and combinations. They are cool weather tolerant and relatively pest-free. Still, there are reasons why geraniums may not bloom.
Geraniums need a minimum of six hours of direct sunlight each day. If they are planted in a shady location, they won’t produce blooms. Consider moving the plants to a sunnier location and their vigor should return.
Geraniums prefer a fairly steady temperature range. Daytime temperatures of 70 to 80 degrees Fahrenheit with night temperatures of about 60 degrees are ideal. Hotter temperatures can prevent blooming. Consider planting geraniums at a different time of year or moving the plants indoors during peak summer heat.
A general fertilizer with a ratio of 10-10-10 or 5-10-10 can be used at a rate of 2 lb. per 100 square feet of soil. An alternative is to mix 2 tsp. of 20-20-20 fertilizer in 1 gallon of water and apply a good dousing once every three weeks. More than this can cause geraniums to fail to bloom.