Pelargoniums are popular flowering plants, bringing vibrant color to gardens and homes. Though often called “geraniums,” they are distinct from the true Geranium genus, though both belong to the Geraniaceae family. These familiar bedding plants are Pelargoniums, valued for their versatility.
Understanding Pelargoniums
Pelargoniums are diverse flowering plants native to South Africa. They thrive in warm, sunny climates, exhibiting heat and drought tolerance. Centuries of hybridization have created numerous cultivars with varied forms and flower colors.
Several main types of Pelargoniums are commonly grown. Zonal Pelargoniums (Pelargonium x hortorum) have upright, bushy growth, often with a distinct dark band on their rounded leaves. Ivy-leaved Pelargoniums (Pelargonium peltatum) trail with fleshy, lobed leaves, suitable for hanging baskets. Scented-leaf Pelargoniums, from various species, are grown for aromatic foliage that releases fragrances like rose, lemon, or mint when touched. Regal or Martha Washington Pelargoniums (Pelargonium x domesticum) are known for large, showy flowers with ruffled petals and intricate patterns.
Essential Care for Pelargoniums
Pelargoniums need adequate light. Most varieties thrive in full sun, requiring at least six hours daily for optimal flowering. In hotter climates, afternoon shade protects them from excessive heat; Regal Pelargoniums may prefer partial shade. Insufficient light leads to leggy growth and reduced blooms.
Proper watering is important; Pelargoniums prefer to be kept slightly dry. Allow soil to dry out between waterings, avoiding complete aridity. Overwatering causes root rot, so deep, less frequent watering is more beneficial. Ideal soil is fertile, well-drained, with a slightly alkaline to neutral pH. Potting mixes should contain perlite or vermiculite for drainage.
Regular fertilization supports abundant flowering. Apply a balanced liquid fertilizer every two to three weeks, or a slow-release fertilizer in spring and mid-summer. Once flowers form, switch to a high-potassium fertilizer, like tomato feed, every 10-14 days to encourage more blooms. Pelargoniums prefer warm temperatures and are sensitive to frost, hardy in USDA Zones 10-11. Temperatures below 50°F (10°C) cause cold damage, leading to yellowing leaves and stunted growth.
Pruning and Propagating Pelargoniums
Pruning Pelargoniums encourages bushier growth and more blooms. Deadheading, removing spent flowers, directs the plant’s energy to new blooms instead of seed. Pinching back shoot tips in spring or early summer promotes a denser, more compact habit by encouraging side branching and preventing legginess.
Propagating Pelargoniums from stem cuttings creates new plants. Use non-flowering side shoots, 4-6 inches long. Remove lower leaves and allow the cut end to dry for a few hours to form a callus. Place cuttings in moist, well-draining rooting medium or water; rooting occurs within two to three weeks. Once rooted, pot young plants individually.
Addressing Challenges and Winter Care
Pelargoniums may encounter pests and diseases. Common insect pests include aphids, whiteflies, and spider mites. Aphids cluster on new growth, whiteflies are found on leaf undersides, and spider mites cause webbing and leaf discoloration in dry conditions. Root rot (from overwatering) and fungal spots like rust or gray mold are common diseases. Regular inspection and good air circulation help prevent issues.
In colder climates, where Pelargoniums are not hardy perennials, overwintering is essential. Bring potted plants indoors before the first frost, placing them in a bright, cool location with reduced watering. Another option is to store dormant plants: dig them up, shake off excess soil, and hang them upside down in a cool, dry, frost-free area like a basement. Alternatively, take stem cuttings in late summer to overwinter smaller plants indoors for a fresh start next spring.