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Trillium
Trillium
Trillium blooms from April through May.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Trillium
Plant it in full shade. It prefers moderate water. It is hardy in USDA zones 4–8. Expect it to reach about 12 in tall and 12 in wide at maturity, in roughly 3 years (not yet checked).
What this means
Written with AI assistance and not yet checked plant by plant against recorded sources, so treat every fact above as a starting point. Its scientific name was checked against botanical registries, an audit keeps its values consistent with the rest of the library, and a July 2026 review re-read the main facts of every plant then in the library against horticultural authorities without recording a source for each, which is why none of that counts as checked here. The source-by-source check is working through the whole library in the open, and a checked plant says so in this row.
When to plant Trillium
Plant Trillium in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 6, the middle of its hardy zones 4 to 8, spring means March to May and fall means August or September. Once settled, it blooms from April to May.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Trillium get?
12 intall5 ft 7 inan adult12 inwideSee Trillium in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Trillium
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Trillium about 12 in apart, center to center, so each plant has room to reach its full width.
Add Trillium to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Good to know about Trillium
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note. A note reports what its source says; where that differs from a fact above, the fact above is this entry's stored value, and its mark says whether it has been checked.
Safety
The berries and rhizome are mildly toxic if eaten, rich in steroidal saponins that upset the stomach. NC State rates the poison severity low. per NC State and Frontiers in Chemistry
Worth knowing
Ants plant the next generation: each seed carries a fatty treat called an elaiosome, so ants haul it off, eat the treat, and leave the seed to grow. per Illinois Extension and Ecology and Evolution
Never cut the leaves
The three green leaves are its only food-making surface for the whole year. Cut or mow them and you starve the rhizome; let them die back on their own. per NC State
Vanishes by mid-summer
By mid-summer the whole plant yellows and vanishes underground until spring. Mark the spot so you don't dig into the dormant rhizome by mistake. per NC State
Deer browse it heavily
White-tailed deer browse it heavily, stripping both flower and leaves. That prevents seed and starves the rhizome, so fence it or expect local decline. per NC State
Never dig from the wild
Buy only nursery-propagated plants and never dig or pick trilliums from the wild. Such transplants rarely survive, and colonies recover on a timescale of decades. per Illinois Extension and USDA Forest Service
What pairs well with Trillium
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Northern Sea Oats
Takes part shade to full shade and moderate water; blooms in midsummer, extending the bed's season; its seed heads stand through winter, for structure and the birds; taller at 3.5 ft, for the layer behind it.
Rhododendron
Takes part shade to full shade and moderate water; overlaps, then carries the display into early summer; evergreen, so the bed keeps its shape through winter; taller at 6 ft, for the layer behind it.
Goatsbeard
Takes part shade to full shade and moderate water; blooms in early summer as this one finishes; taller at 4 ft, for the layer behind it; both are North American natives.
Hellebore
Takes part shade to full shade and moderate water; opens in late winter and overlaps into this one's season; evergreen, so the bed keeps its shape through winter; a soft color beside the white.
Camellia
Takes part shade to full shade and moderate water; blooms in midwinter, before this one opens; evergreen, so the bed keeps its shape through winter; stands well above at 6.5 ft, a canopy to plant beneath; they only overlap in zones 7 to 8.
Meadow Rue
Takes part shade to full shade and moderate water; blooms in early summer as this one finishes; taller at 4 ft, for the layer behind it; a soft color beside the white.
Wishbone Flower
Takes part shade to full shade and moderate water; blooms in early summer as this one finishes; lower at 10 in, for the front of the border; a soft color beside the white.
Snowdrop
Takes part shade to full shade and moderate water; blooms in late winter, before this one opens; lower at 5 in, for the front of the border; its white flowers settle the white.
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Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.