Native to South Africa, geraniums are a staple annual flower in gardens in most parts of the world. Their brightly colored red, pink, fuchsia, coral and white flowers bloom continuously until killed by frost in the garden. Geraniums also grow well indoors to provide color during the bleak winter months.
Geraniums growing indoors in pots do best when fertilized with a water-soluble houseplant fertilizer. Feed them every month during spring and summer. When autumn arrives, begin to feed them only every other month until spring.
Add fertilizer directly to the soil of geraniums growing in containers outdoors. Add 1/2 tsp. granulated, well-balanced, complete garden fertilizer along with 1 tsp. dolometic limestone per each 8-inch pot. Mix well before transplanting geranium seedlings.
Incorporate granulated garden fertilizer labeled 5-10-5 (for the percentages of nitrogen, phosphorus and potassium) into the soil of the garden bed before planting. Apply 2 lbs. of fertilizer for every 100 square feet of garden bed. Every four to six weeks during the growing season, side dress geraniums with a 10-10-10 fertilizer by sprinkling 2 lbs. for each 100 square feet of garden bed.