Over 200 different species of geraniums exist. These popular flowers, which come in a huge variety of sizes, shapes, colors and even scents, are most often grown as annuals, although they can be wintered over in some climates. Geraniums can be planted in hanging baskets, containers or as bedding plants. When proper care, they will provide you with vibrantly colored blooms all summer long and even into the fall in some climates.
Wait for a day in the spring, when all danger of frost is past and the ground is thawed and warm.
Choose a planting site that has well-draining soil and is exposed to at least 6 hours of sunlight per day. If you live in an area that has very hot summers, choose a site that gets some afternoon shade, as too much exposure to hot sun can cause geraniums to fade and wilt. Containers should have drainage holes and be at least twice as wide and deep as the plant's root ball. Mildly acidic soil (pH level 6.0-6.5) is best.
Dig a hole as large as the young geranium plant's container. Gently ease the root ball out of the container, and place it in the hole. Back fill the hole and tamp down the soil, then water thoroughly. If planting your geranium in a container, line the bottom with gravel to aid in draining, then fill with soil until the top of your geranium's root ball is level with the rim of the container.
Fertilize your newly planted geranium with a fertilizer rich in phosphorus, which is represented by the second number in the nutrient count on bags of fertilizer. A fertilizer with the numbers 10-20-10, for example, is a good choice. Phosphorus is important for strong root development. Continue to fertilize your geraniums with the same fertilizer every month.
Add a layer of mulch after planting to prevent weed growth and help the soil maintain moisture. Water your young geraniums throughout the growing season as soon as the top layer of the soil dries out.