Geraniums are popular flowering plants, celebrated for their bright blooms and relatively straightforward care requirements. The plants commonly grown in gardens and containers are technically Pelargonium species, which are tender perennials treated as annuals in many climates. These South African natives offer many colors and foliage patterns, making them a fixture in summer landscapes and window boxes. Their appeal lies in their long flowering season and ability to thrive with consistent care.
Setting the Stage: Light and Soil
Geraniums perform best with ample sunlight, requiring at least six hours of direct sun daily to promote vigorous blooming. While they can tolerate some partial shade, too little light results in leggy growth and fewer flowers. A sunny location protected from intense midday heat is ideal for maintaining plant health and flower production.
Soil composition is important, as geraniums are sensitive to standing water around their roots. They require a planting medium with excellent drainage. A standard, well-draining potting mix is suitable for containers, but heavy clay soil should be amended with organic matter, perlite, or coarse sand to improve aeration and drainage for in-ground planting.
Geraniums prefer a soil pH that is slightly acidic to neutral, ideally between 6.0 and 7.0. This range ensures the plant can efficiently absorb necessary nutrients for growth and flowering. Containers must always have drainage holes to allow excess water to escape, preventing root rot.
The Art of Watering and Feeding
Monitoring soil moisture is crucial, as overwatering is the primary cause of plant decline. Use the “dry-out” approach: allow the top inch or two of soil to dry completely before watering again. When watering, soak the soil thoroughly until water runs out of the drainage holes, ensuring the entire root zone is saturated.
Container plants require more frequent watering than those in the ground because pot soil dries out faster. During high heat, container plants may need daily checks to prevent root desiccation. Avoid overhead watering, as wet foliage encourages fungal diseases.
Geraniums benefit from regular fertilization throughout the active growing season to sustain continuous flowering. For container plants, apply a balanced, water-soluble fertilizer (e.g., 10-10-10 or 20-20-20) every two to four weeks. Once flowering begins, switching to a high-phosphorus formula (e.g., 15-30-15) helps maximize bloom production. Slow-release granular fertilizers can also be incorporated into the soil at the beginning of the season.
Routine Maintenance: Pruning and Deadheading
Deadheading, the removal of spent flowers, encourages a continuous flush of new blooms. Allowing old flowers to remain causes the geranium to divert energy toward producing seeds rather than new buds. To deadhead properly, remove the entire flower stalk by pinching or snipping it back to the nearest leaf node or the main stem.
Regular pruning maintains a dense, bushy shape and prevents the plant from becoming long and sparse. For young plants, encourage branching by “pinching back” the growing tips of the stems. More aggressive pruning should be performed in late summer or early fall to shape the plant and prepare it for dormancy.
To manage size, cut the stem back by about one-third to one-half, making the cut just above a leaf node where new growth can emerge. This structural maintenance rejuvenates the plant and increases growing points, leading to a fuller appearance. Always use clean, sharp shears to make precise cuts and minimize the risk of introducing disease.
Seasonal Care: Overwintering Geraniums
Since Pelargonium species cannot survive freezing temperatures, gardeners in colder climates must preserve their plants over winter. A common method is to bring potted geraniums indoors before the first frost and treat them as houseplants. Prune the plant back by about a third to a half and place it in a bright, sunny window where temperatures remain between 60°F and 65°F.
During the winter months, the plant’s growth naturally slows, so both watering and feeding should be significantly reduced. Water only when the topsoil is completely dry, and suspend all fertilization until new growth resumes in the spring. Another option is to store the plants in a dormant state by digging up the plant before frost, shaking the soil from the roots, and placing them bare-root in a paper bag or hanging them upside down.
These dormant plants should be stored in a cool, dark, and dry location, such as a basement or garage, where temperatures stay between 45°F and 50°F. The bare roots require minimal moisture; check them monthly and lightly mist them if they appear shriveled. Taking 3-to 4-inch stem cuttings in late summer is also a popular way to propagate new plants, ensuring a fresh supply for the following spring.