Use & Care NotesCompanion Plants
Rule of Plum Daylily: Near-Black Plum Beside Silver Lavender
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Rule of Plum daylily has 3-inch flowers in one of the deepest purples found in daylilies, almost black in shade, with a small yellow-green throat and slightly crisped inner petals. Even the unopened buds are nearly black-purple, so the plant looks dramatic before a single flower opens. It is a new introduction, registered in 2025.
Rule of Plum at a glance
| Trait | What to expect |
|---|---|
| Botanical name | Hemerocallis 'Rule of Plum' |
| Flowers | Very deep plum purple, about 3 inches, yellow-green throat |
| Buds | Nearly black-purple |
| Size | Scapes about 27 inches; foliage about 16 inches tall, 18 to 24 inches wide |
| Bloom | Starts late June, peaks early July, occasional late repeat |
| Hardiness | USDA zones 3 to 9 |
| Light | Full sun to light part shade |
| Fragrance | Light and sweet, noticeable up close |
Dark plum and silver
Rule of Plum is a daylily in lavender's own color family, only several shades darker. That is what makes it useful. Next to lavender's silver-gray leaves and lighter purple spikes, the near-black plum flowers read as deep shadows that give the planting depth. It blooms with the lavender, from late June into early July, so the effect lands right at peak season.
To keep dark flowers from disappearing into the green, give them a light background. A white or pale pink companion behind or beside them, or simply lavender's silver foliage in front, makes the plum glow. Its compact size works in the middle of a bed or in groups between lavender. Sketch it in the Companion Plant Planner.
Planting and care
- Planting: soak the bare root fans, set the crown about an inch below the surface and water well.
- Sun: at least six hours. Light afternoon shade helps the dark petals hold their color.
- Water: regularly the first season; then it handles heat, clay and dry spells.
- Tidying: snap off each day's faded flowers and cut bare scapes to the base.
- Problems: leaf streak in wet summers; crown rot in soggy soil.
- Dividing: every few years in spring.
Fall and winter
Rule of Plum is a dormant type, so its foliage dies back completely in fall. It is fully hardy in Michigan. Clean up the dead leaves after a hard frost and keep it out of low spots where water stands. The Care Calendar can remind you when to do it.
Frequently asked questions
Is the flower really black?
It is very deep plum purple. In shade or low light it can look almost black, and the buds are nearly black-purple.
Are daylilies safe for cats?
No. All parts are toxic to cats, so keep that in mind if you have one.
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