Regal geraniums, also known as Martha Washington geraniums, are flowering perennials valued for their large, ornamental flowers and ease of care. Plants bloom during late spring, producing flowers in shades of red, white, purple and pink. Each flower usually consists of white and a second color, depending on the variety. Native to South Africa, regal geraniums require warm temperatures throughout the year to thrive, making them common houseplants in temperate regions. Container-grown plants are usually found in nurseries and garden centers in late winter and early spring.
Keep regal geraniums in a location that receives bright morning sun and partial afternoon shade, such as an east-facing window. Maintain average temperatures of 60 to 80 degrees Fahrenheit during spring and summer, while the plants are actively growing.
Water regal geraniums once every five days to keep the soil consistently moist, but not soggy. Reduce the frequency of watering during winter to once every seven to 10 days, allowing the top 1 to 2 inches of soil to dry slightly between applications.
Feed regal geraniums once every one to two weeks using a liquid houseplant fertilizer at half the rate recommended by the manufacturer. Water both before and after applying to prevent root burn or injury, and to help the nutrients penetrate the soil.
Cut the plant back to 4 inches in height immediately after flowering ends in summer. Re-pot the plant in a slightly larger container with fresh potting soil, and water lightly once per week to prevent the soil from drying out completely. Cease fertilizing until mid-summer.
Transfer the plant outdoors during fall, when nightly temperatures drop to about 55 degrees Fahrenheit, for six weeks. Move the plant back to its original position and resume regular care after the six weeks have passed. This period of cool weather is necessary for regal geraniums to bloom the following season.