Cold hardiness & minimum temperature

Is Tuolumne Fawn Lily (Erythronium tuolumnense)cold hardy? Hardiness zone & min temp

Also called Tuolumne fawn lily, Tuolumne dogtooth violet, Pagoda lily.

More about tuolumne fawn lily

About Tuolumne Fawn Lily

Erythronium tuolumnense · also called Tuolumne fawn lily, Tuolumne dogtooth violet · flowering

Endemic to the Sierra Nevada foothills of Tuolumne County in California, Erythronium tuolumnense is a spring-ephemeral woodland bulb producing bright yellow, reflexed flowers and a pair of plain mid-green, unmarked leaves on reddish stalks — unlike the mottled foliage of many other Erythronium species. It thrives in dappled shade with consistently moist, humus-rich soil and goes completely dormant by early summer. The most critical care point is to keep the bulbs moist even during dormancy, as drying out is fatal. It is not considered toxic to cats or dogs.

Cold limit: USDA 3-9 · RHS H7 (-20 to 20°C)

Watch for — Bulb rot from desiccation or waterlogging: Bulbs perish if they dry out during summer dormancy or sit in waterlogged soil in winter. Plant in well-drained but moisture-retentive soil, apply a cool mulch to prevent drying, and avoid planting in frost pockets where standing water accumulates.

What tuolumne fawn lily's hardiness rating actually means

Yes — tuolumne fawn lily is genuinely cold hardy. Rated RHS H7 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 3-9 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly below about −20 °C. Tuolumne Fawn Lily is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for tuolumne fawn lily as it gets too cold:

It tolerates winter lows to about −20 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can tuolumne fawn lily go outside or overwinter — and where?

Plant it out within USDA 3-9 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when tuolumne fawn lily can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Tuolumne Fawn Lily hardiness — frequently asked questions

Is tuolumne fawn lily cold hardy?

Yes — tuolumne fawn lily is genuinely cold hardy. Rated RHS H7 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Tuolumne Fawn Lily is hardy across USDA 3-9; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature tuolumne fawn lily can survive?

Minimum survivable temperature is roughly below about −20 °C. Tuolumne Fawn Lily is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is tuolumne fawn lily?

Tuolumne Fawn Lily is rated USDA 3-9 and RHS H7 — Hardy in the severest European continental winters.

Can tuolumne fawn lily survive winter outside?

Plant it out within USDA 3-9 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to tuolumne fawn lily below its minimum temperature?

It tolerates winter lows to about −20 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.