Cold hardiness & minimum temperature

Is Threadleaf Tickseed 'Moonbeam' (Coreopsis verticillata)cold hardy? Hardiness zone & min temp

Also called Moonbeam Coreopsis, Whorled Tickseed, Thread-leaf Coreopsis.

More about threadleaf tickseed 'moonbeam'

About Threadleaf Tickseed 'Moonbeam'

Coreopsis verticillata · also called Moonbeam Coreopsis, Whorled Tickseed · flowering

Coreopsis verticillata 'Moonbeam' is a long-blooming prairie perennial producing a months-long display of soft, pale yellow daisy-like flowers from early summer to autumn above delicate, thread-like foliage. It is highly drought-tolerant once established, requiring little maintenance. Considered non-toxic to pets based on ASPCA data for Coreopsis.

Cold limit: USDA 3-9 · RHS H6 (-20-35°C)

What threadleaf tickseed 'moonbeam''s hardiness rating actually means

Yes — threadleaf tickseed 'moonbeam' is genuinely cold hardy. Rated RHS H6 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. 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 about −20 to −15 °C. Threadleaf Tickseed 'Moonbeam' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for threadleaf tickseed 'moonbeam' as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 threadleaf tickseed 'moonbeam' 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 threadleaf tickseed 'moonbeam' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Threadleaf Tickseed 'Moonbeam' hardiness — frequently asked questions

Is threadleaf tickseed 'moonbeam' cold hardy?

Yes — threadleaf tickseed 'moonbeam' is genuinely cold hardy. Rated RHS H6 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Threadleaf Tickseed 'Moonbeam' 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 threadleaf tickseed 'moonbeam' can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Threadleaf Tickseed 'Moonbeam' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is threadleaf tickseed 'moonbeam'?

Threadleaf Tickseed 'Moonbeam' is rated USDA 3-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can threadleaf tickseed 'moonbeam' 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 threadleaf tickseed 'moonbeam' below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.