Geraniums are popular flowering plants, widely admired for their vibrant colors and ease of care. They bring cheerful hues to gardens, containers, and hanging baskets alike. Their popularity stems from their versatility and continuous blooming, making them a favored choice for consistent floral display.
Understanding Geranium Varieties
The term “geranium” can cause confusion, as it commonly refers to two distinct plant genera: Pelargonium and Geranium. What most people recognize as common annual “geraniums” in hanging baskets are actually Pelargoniums, often treated as tender annuals. True Geraniums, also known as hardy geraniums or cranesbills, are perennial plants that withstand colder temperatures and return year after year.
Several Pelargonium varieties exist. Zonal geraniums (Pelargonium x hortorum) have upright growth, sturdy stems, and often a distinctive dark band on their leaves. Ivy geraniums (Pelargonium peltatum) have trailing habits and ivy-shaped leaves, ideal for hanging baskets and window boxes. Scented geraniums are cultivated for their fragrant foliage, releasing scents like rose, lemon, or peppermint when touched. Regal geraniums (Martha Washington geraniums) are prized for their large, showy blooms.
Planting and Ongoing Care
Light Requirements
Geraniums thrive in locations that receive ample sunlight. For best blooming, they need at least six hours of direct sun exposure daily. In regions with intense summer heat, providing some afternoon shade can be beneficial to prevent scorching. While they appreciate bright conditions, consistent light is more important than extreme heat.
Soil and Potting
Well-draining soil is crucial for healthy geranium growth, whether planted in the ground or in containers. They prefer a slightly acidic to neutral pH. For potted geraniums, using a quality potting mix and a container with drainage holes prevents waterlogging. Geraniums can tolerate being somewhat root-bound, so frequent repotting is unnecessary.
Watering Techniques
Proper watering involves allowing the soil to dry out between waterings. Deep watering, rather than frequent shallow watering, encourages stronger root development. Potted plants require more frequent watering than those in the ground, as container soil dries out faster. Signs of overwatering include yellowing leaves, especially at the bottom of the plant.
Feeding Your Geraniums
During their active growing season, geraniums benefit from regular fertilization to support growth and flowering. A balanced fertilizer or one higher in phosphorus can promote more blooms. For in-ground plants, a slow-release granular fertilizer applied in spring suffices, while potted plants benefit from a liquid feed every two to three weeks. Over-fertilizing can lead to excessive foliage at the expense of flowers.
Temperature and Humidity
Geraniums prefer moderate temperatures, thriving in daytime temperatures between 70°F and 85°F (21°C-29°C) and nighttime temperatures from 55°F to 65°F (13°C-18°C). They also prefer moderate humidity levels. Extreme fluctuations in temperature or prolonged periods of high humidity can stress the plants and increase susceptibility to problems.
Pruning for Health and Bloom
Pruning is important for maintaining healthy geraniums and encouraging blooms. Deadheading redirects the plant’s energy from seed production to developing new flowers. This practice helps extend the blooming period throughout the growing season.
Pinching back leggy stems promotes bushier, more compact growth. Best done in early spring to encourage branching, it can continue throughout the season to maintain form. Regular pruning enhances the plant’s appearance and improves air circulation, preventing fungal issues.
Addressing Common Geranium Problems
Geraniums may show signs of distress, with yellowing leaves being a common sign. This can be caused by overwatering or underwatering, nutrient deficiencies, or insufficient light. Adjusting watering habits and ensuring adequate sunlight often resolves this. Lack of blooms usually points to inadequate light or an imbalance in fertilizer.
Common pests such as aphids and whiteflies can infest geraniums. These are managed with insecticidal soap or rinsing with water. Fungal issues like rust or botrytis blight occur, especially in humid conditions. Good air circulation and watering at the soil level rather than overhead prevent these problems.
Overwintering Geraniums
For gardeners in colder climates where Pelargoniums are not hardy, overwintering them extends their life beyond a single season. One method is bringing potted plants indoors before the first hard frost. Place these plants in a bright location and water sparingly, allowing the soil to dry out between waterings.
Another approach is to take cuttings from healthy plants in late summer, rooting them indoors for new plants next spring. Alternatively, gardeners can store dormant plants bare-root in a cool, dark, dry location (e.g., basement, garage) after digging them up and shaking off excess soil. This requires re-potting and gradually reintroducing plants to light in early spring.