My Castle Lupine is a hardy, long-lived perennial that brings vertical drama to garden borders with spiky flower spikes reaching 24 to 40 inches tall. This open-pollinated cultivar of Lupinus polyphyllus thrives in partial shade across hardiness zones 4 through 8, rewarding gardeners with 150 to 190 days of growth before reaching full bloom. Though it demands patience, this lupine flowers abundantly and holds its blooms exceptionally well, making it one of the most reliable perennials for cut flower arrangements and garden structure.
Partial Shade
Moderate
4-8
40in H x ?in W
—
Low
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Hardy perennials that establish deep, robust root systems and persist year after year with minimal fussing. Johnny's Selected Seeds notes these are long-lived, easy-to-maintain plants that reward thoughtful seed starting with superior flowering. The variety develops strong taproots when given room to expand during seedling stage, which translates directly to vigorous, floriferous adult plants. At 24 to 40 inches, these lupines provide substantial garden presence without requiring staking or constant tending.
My Castle Lupine excels as a cut flower, with spikes that open progressively along the stem, offering long-lasting arrangements. The 150 to 190 day cycle from seed to bloom allows for extended seasonal planning, whether you're growing for early summer color or succession plantings. In the garden, the vertical architecture of these spikes creates striking focal points in borders and cottage garden designs.
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Sow seeds indoors 4 to 8 weeks before your last spring frost. Use deep cell trays such as 50-cell Deep or 32-cell trays to accommodate the vigorous taproots that lupines develop; avoid shallow trays like standard 50-cell or 72-cell unless you plan to transplant quickly. Thin seedlings to one plant per cell once the first true leaves appear, giving roots room to expand. Lupine seedlings tolerate light frost, so they can be hardened off and moved outdoors even when cool weather lingers.
Transplant hardened-off seedlings outdoors after the last spring frost, spacing plants 18 inches apart. These lupines tolerate cool conditions and can go in the ground while nights are still chilly. Ensure transplants are not confined in cells too long, as root-bound seedlings produce inferior mature plants and flowers.
Cut flower spikes for arrangements once 80 percent of the blooms on each spike have opened, a point where the spike still has days of vase life ahead. Cut stems in early morning when flowers are fully hydrated, using sharp shears to take stems as long as desired while leaving foliage intact on the plant.
Deadhead spent flower spikes to encourage additional blooms later in the season. For overwintering perennials, leave flower stems standing through fall and winter to provide garden structure and allow natural seed drop, cutting them back in early spring as new growth emerges.
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