Geraniums, belonging to the genus Pelargonium, are among the most popular flowering plants in US gardens. Known for their vibrant blooms, aromatic foliage, and adaptability, they thrive in various climates. While true geraniums (Geranium spp.) are hardy perennials, the commonly cultivated "geraniums" in the US are tender perennials or annuals, often grown for their showy flowers and ease of care.
Zonal geraniums are the most recognizable variety, named for the dark "zones" on their leaves. They produce large, rounded flower clusters in shades of red, pink, white, and purple. These plants prefer full sun and well-draining soil, making them ideal for borders, containers, and bedding displays. Popular cultivars include 'Americana Red', 'Maverick Star', and 'Ringo 2000'.
Ivy geraniums are trailing varieties with glossy, ivy-shaped leaves and cascading growth habits. They excel in hanging baskets and window boxes, producing prolific blooms in spring and summer. Colors range from soft pastels to deep purples. Notable cultivars include 'Blizzard Blue', 'Tempo Hot Pink', and 'Summer Showers'. They thrive in partial shade and require consistent moisture.
Scented geraniums are prized for their fragrant foliage, which releases aromas like rose, lemon, mint, or cinnamon when touched. While their flowers are smaller, their leaves are often used in potpourri or culinary applications. Varieties include 'Attar of Roses' (rose-scented), 'Citronella' (mosquito-repellent), and 'Lemon Fancy'. They prefer sunny locations and light pruning to maintain bushiness.
Regal geraniums, also called Martha Washington geraniums, feature large, ruffled flowers with striking color patterns. They bloom profusely in cooler spring temperatures and prefer partial shade in hot climates. Popular cultivars include 'Lord Bute' (deep purple with white edges) and 'White Glory'. They require well-draining soil and benefit from deadheading to prolong flowering.
Unlike tender Pelargoniums, true hardy geraniums are perennial and survive freezing temperatures. They offer delicate, five-petaled flowers and lobed foliage, thriving in USDA zones 3–9. Notable varieties include 'Rozanne' (long-blooming blue), 'Johnson's Blue' (violet-blue), and 'Bloody Cranesbill' (deep magenta). They are low-maintenance and ideal for ground cover or woodland gardens.
Angel geraniums are compact hybrids with small, pansy-like flowers and serrated leaves. They resemble regal geraniums but are more heat-tolerant and suitable for containers. Colors often include bi-colors like lavender and white. 'Angeline' and 'Debbie' are standout cultivars. They perform best in morning sun and afternoon shade with moderate watering.
Less common but noteworthy varieties include 'Stellar' geraniums (star-shaped flowers), 'Phantom' (dark-eyed blooms), and 'Tulip' geraniums (semi-double flowers resembling tulips). These niche varieties add diversity to gardens and are often sought after by collectors.
Most geraniums thrive in full sun (6+ hours daily) and well-draining soil. Water when the top inch of soil is dry, and fertilize monthly during the growing season. Deadhead spent blooms to encourage reblooming. In colder regions, tender varieties can be overwintered indoors or propagated from cuttings.
Geraniums may face issues like whiteflies, spider mites, or fungal diseases such as botrytis. Prevent problems by ensuring good air circulation, avoiding overhead watering, and using insecticidal soap for pests. Hardy geraniums are generally more resistant to diseases.
