Giant Hyssop Agastache is a fragrant perennial flower that blooms from early summer through late fall, reaching 24 to 36 inches tall with a naturally spreading habit. Hardy in zones 5 through 5, this low-maintenance heirloom thrives in full sun and tolerates drought once established, asking for little water or fussing. The showy flower spikes are excellent for cutting fresh or drying, and their sweet fragrance draws hummingbirds, butterflies, and other pollinators reliably throughout the growing season.
2
Full Sun
Moderate
6-9
36in H x 24in W
—
High
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This is a flower that genuinely earns its name; the tall, airy spikes of blooms tower above other perennials, creating visual impact without demanding constant attention. The fragrance is immediate and honeyed, noticeable from several feet away. Because it tolerates both drought and deer, it thrives in challenging garden spots where many ornamentals would struggle. The extended bloom window, stretching from June well into November, keeps pollinators and hummingbirds visiting long after most perennials have faded.
Giant Hyssop is grown primarily as an ornamental flower and herb, valued for its tall, airy spikes that add vertical interest to borders and meadow gardens. The blooms are excellent for cutting fresh into arrangements and dry beautifully for winter displays or dried flower crafts. Gardeners also naturalize it in loose, informal plantings where its ability to self-seed lightly creates a relaxed, cottage-garden effect. The plant's pollinator magnetism makes it especially useful in gardens designed to support butterflies, hummingbirds, and beneficial insects.
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Sow seeds indoors in pots 6 to 8 weeks before your last spring frost. Sprinkle seeds on the soil surface and press lightly, as they require light to germinate. Keep the soil evenly moist by placing a humidity dome over containers, or lightly cover the seed tray with fine vermiculite. Maintain temperatures between 65 and 70 degrees Fahrenheit. Seeds typically sprout within 14 to 30 days.
Once seedlings have developed their first true leaves and all danger of frost has passed, harden off plants by gradually exposing them to outdoor light and temperature fluctuations over 7 to 10 days. Transplant into the garden in full sun, spacing plants 2 inches apart.
Direct sow seeds in the garden after all danger of frost has passed. Sow seeds on the soil surface and press them in lightly; do not cover, as they need light to germinate.
Giant Hyssop requires minimal pruning. Deadhead spent flower spikes regularly during the growing season to encourage continued blooming and shape the plant. In late fall or early spring, cut back the previous year's growth to ground level if desired for tidiness, though leaving stems standing through winter provides structure and shelter for overwintering insects.
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