Pelargonium domesticum, commonly known as the Regal Geranium or Martha Washington Geranium, is a highly popular ornamental plant celebrated for its vibrant, showy flowers and attractive foliage. Its striking appearance, often featuring ruffled petals and intricate patterns, makes it a favored choice for adding dramatic splashes of color to gardens and indoor spaces alike.
What is Pelargonium Domesticum
Pelargonium domesticum is distinguished by its substantial, often bi-colored or patterned flowers, up to 5 cm in diameter with a velvety texture. These large blooms, appearing in clusters, showcase a spectrum of colors including pink, red, white, purple, and sometimes orange, often accented with contrasting veins or blotches. The plant typically grows as a bushy, evergreen perennial, reaching heights of 12 to 36 inches (30-90 cm) and spreads of 12 to 24 inches (30-60 cm). Its foliage consists of rounded, heart-shaped to kidney-shaped, deeply serrated mid-green leaves. Pelargonium domesticum is a hybrid, developed from South African wild species like P. grandiflorum and P. cucullatum.
Caring for Your Regal Geranium
Light
Regal Geraniums thrive in bright, indirect light, requiring at least 4-6 hours of daily sunlight for robust growth and abundant blooms. Gentle morning sun with afternoon shade is particularly beneficial, especially in hotter climates. While they can tolerate full sun, excessive direct light, especially during peak hours, can lead to leaf scorch and faded flowers. Indoors, an ideal spot is a few feet away from a well-lit window or near a window with a sheer curtain to diffuse intense light.
Watering
Proper watering prevents common issues like root rot. Regal Geraniums prefer consistently moist soil, but it is important to allow the top inch or two (2-3 cm) of soil to dry out between waterings. During the growing season, watering once or twice a week may be necessary, adjusting frequency based on temperature and humidity. In cooler periods or during winter dormancy, reduce watering significantly, perhaps to once every one to two weeks, ensuring the soil does not become completely dry.
Soil Requirements
Regal Geraniums flourish in well-draining, fertile soil that is slightly acidic to neutral, with a pH range of 5.8 to 7.0. For potted plants, a suitable potting mix often includes components like peat moss, perlite, and compost in equal parts for good drainage and aeration. Adding coarse sand or clay pebbles can further enhance drainage and airflow. When planting in garden beds, amending heavy or clay-like soil with organic matter such as compost or well-rotted manure improves its structure.
Temperature and Humidity
These plants prefer cooler conditions for optimal growth and flowering. Ideal daytime temperatures typically range from 60°F to 75°F (15°C-24°C), with nighttime temperatures ideally between 50°F and 60°F (10°C-16°C). Consistently cool nighttime temperatures are important for bud setting. High temperatures, especially hot and humid summers, can stop flowering.
Regal Geraniums appreciate moderate humidity levels, as overly humid conditions can promote fungal issues. In dry indoor environments, a humidity tray can provide some moisture, but misting should be used cautiously to avoid leaf diseases.
Fertilizing
During the active growing season, from spring through summer, fertilize Regal Geraniums every two to four weeks. A balanced, water-soluble fertilizer with an N-P-K ratio like 10-10-10 or 20-20-20, or one specifically formulated for blooming plants (often higher in phosphorus). Dilute liquid fertilizers to half the recommended strength to prevent nutrient overload and root burn. Cease fertilization in late fall or winter when the plant enters dormancy.
Pruning for Health and Blooms
Regular pruning maintains the plant’s shape, encourages bushier growth, and promotes continuous flowering. Deadhead spent blooms by removing them just above the first set of leaves below the flower. This directs energy towards producing new buds rather than seed development. Additionally, prune back leggy stems to encourage new shoots and a more compact form. Remove any yellow or diseased leaves to maintain overall plant health.
Propagating Regal Geraniums
Propagating Regal Geraniums is achieved through stem cuttings, with late spring or early summer being the ideal time when the plant is actively growing. Select healthy, non-flowering stems. Using clean, sharp scissors or shears, cut a 4-6 inch (10-15 cm) piece of stem just below a leaf node, ensuring each cutting has at least three sets of leaves.
Prepare the cutting by removing the leaves from the lower half to prevent moisture loss and potential rotting once planted. Dipping the cut end into rooting hormone encourages faster root development. Plant the prepared cutting into a small pot filled with a well-draining potting mix, burying the leaf nodes where the lower leaves were removed. Water the soil gently to settle the cutting, keeping the mix moist but not waterlogged, and cover the pot with a plastic bag or clear cover to maintain humidity. Roots typically emerge within two to three weeks, and new leaves indicate it is ready for transplanting into a larger pot.
Common Problems and Solutions
Root rot is a frequent problem, caused by overwatering or inadequate drainage. Symptoms include wilting, yellowing leaves, and soft, decaying stems. To remedy, ensure pots have drainage holes, allow the soil to dry between waterings, and consider repotting with fresh, well-draining soil after trimming affected roots.
Pests like aphids, whiteflies, and spider mites can infest Regal Geraniums. Whiteflies often manifest as small white insects on the undersides of leaves, while spider mites may cause fine webbing and parched leaves. Aphids are small, soft-bodied insects that cluster on new growth. Insecticidal soap or neem oil spray can treat these infestations, applied according to product instructions.
Yellowing leaves may indicate overwatering, underwatering, or nutrient deficiencies, particularly nitrogen. Leggy growth with sparse leaves often results from insufficient light. Moving the plant to a brighter location can help correct this. Flower bud drop can occur due to sudden temperature changes, improper watering, or high humidity.