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