Giant Dahlia is a stunning open-pollinated cultivar that delivers exactly what its name promises: large, radiant blooms in a vibrant mix of colors. Hardy in zones 7, 11, these compact plants reach 40, 60 inches tall and flower reliably in 75, 90 days from transplant, making them a dependable choice for mid to late-season color. Sow indoors 4, 5 weeks before your last frost, or direct seed after soil warms to 65, 70°F, and you'll have a garden full of showstopping dahlias perfect for cutting.
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7-11
60in H x ?in W
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Moderate
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These dahlias produce genuinely large blooms on plants with a tidy, manageable growth habit, rather than sprawling vines that demand constant tying. The colorful mix keeps you guessing at what you'll get with each plant, and starting from seed is straightforward if you follow Johnny's transplant method: sow in flats, pot up seedlings before they become root-bound, and transplant out once soil has warmed. Harvest blooms before they fully open for longer vase life.
Giant Dahlia is grown primarily as a cut flower. The large, colorful blooms are perfect for arrangements and bouquets, and harvesting them before they fully open extends their vase life significantly.
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Sow seeds 4, 5 weeks before your last frost date. Cover seeds lightly with growing medium and keep the soil surface moist until emergence. Once seedlings develop true leaves, transplant into larger cell packs. Do not allow seedlings to become root-bound and avoid disturbing roots during transplanting, as this slows establishment.
Transplant into the garden after the last frost when soil has warmed. Space plants 9 inches apart. Harden off seedlings gradually before moving them outdoors to reduce transplant shock.
Direct sow after the last frost when soil temperature reaches 65, 70°F (18, 21°C). Sow thinly at a rate of 2 seeds per foot, 1/4 inch deep. Cover lightly but firmly and keep the soil surface moist until seedlings emerge.
Cut blooms before they are completely open for the longest vase life. This technique also encourages the plant to produce additional flowers throughout the season.
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