Regal geraniums are the aristocrats of the Pelargonium world, with showy flowers in shades of pink, purple, lavender, and red that often feature striking speckles and splotches. These hybrid plants, derived from crosses between Pelargonium grandiflorum and Pelargonium cucullatum, grow 12 to 36 inches tall on somewhat woody stems clothed in heart-shaped to kidney-shaped leaves with crinkled margins. Hardy only in zones 10-11, they're treasured as seasonal bloomers in cooler climates when grown as annuals, valued for their dramatic flower clusters that emerge reliably from consistently cool nights.
18
Partial Sun
Moderate
10-11
36in H x 24in W
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Moderate
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Regal geraniums demand cool nighttime temperatures to perform their best, which is why they shine in spring and fall rather than summer heat. Their flowers are genuinely showy, arriving in clusters with distinctive markings and speckles that feel almost painted. Grown as potted plants for deck and patio displays, they transition beautifully indoors as houseplants during the cooler months, making them more of a seasonal treasure than a year-round commitment.
Regal geraniums serve as seasonal flowering plants for container gardening on decks and patios, thriving in spring and fall when nighttime temperatures stay cool. In frost-free zones, they can be overwintered as houseplants to enjoy their showy blooms indoors during winter months. Many gardeners treat them as annuals, purchasing potted specimens in flower and enjoying them for a season before replanting.
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Transplant purchased potted regal geraniums outdoors after the last spring frost, when both day and nighttime temperatures are reliably mild. Space plants 12 to 24 inches apart to accommodate their mature width.
Deadhead spent flowering stems promptly to maintain a tidy appearance and encourage continued blooming. The somewhat woody growth habit means plants may become leggy over time; pinching back stems in early spring helps promote bushier, more compact growth.
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“Regal geraniums, also known as Martha Washington geraniums, represent a deliberate hybridization program combining two South African Pelargonium species: Pelargonium grandiflorum and Pelargonium cucullatum. These crosses created a distinct class of geraniums valued for their large, ornate flowers and compact growth. The common name 'Martha Washington' likely reflects their popularity during the early to mid-twentieth century, when they became fixtures in American homes and gardens, though the breeding work took place primarily in European horticultural centers.”