Why Didn’t My Martha Washington Geranium Bloom All Summer?

Question:

I planted a Martha Washington geranium outdoors in spring. Unfortunately, it didn't bloom all summer. Why?

Answer:

Martha Washington or regal geraniums (Pelargonium x domesticum) produce beautiful flowers.  Unfortunately, cool (50 to 60°F), night temperatures are required for flower formation.  Few flowers form during the summer months in Iowa because nighttime temperatures are usually too high.  The common garden geranium (Pelargonium x hortorum) and ivy geranium (Pelargonium peltatum) are more heat tolerant and better choices for Iowa gardens.