Cold hardiness & minimum temperature

Is Eleocharis acicularis (Eleocharis acicularis)cold hardy? Hardiness zone & min temp

Also called dwarf hairgrass, needle spikerush.

More about eleocharis acicularis

About Eleocharis acicularis

Eleocharis acicularis · also called dwarf hairgrass, needle spikerush · tropical

Dwarf hairgrass is a popular aquarium carpeting plant with thin, grass-like blades that spread by runners to form a lush green lawn across the foreground. Grown submerged under good light and CO2 it carpets quickly and dense. A temperate-to-subtropical spikerush, it is one of the most widely used aquascaping foreground grasses.

Cold limit: USDA 5-10 (cold-tolerant aquatic; grown indoors in aquaria and outdoors in ponds in mild zones) (18-26°C)

What eleocharis acicularis's hardiness rating actually means

Yes — eleocharis acicularis is genuinely cold hardy. Rated RHS H6 and USDA 5-10 (cold-tolerant aquatic; grown indoors in aquaria and outdoors in ponds in mild zones), 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 5-10 (cold-tolerant aquatic; grown indoors in aquaria and outdoors in ponds in mild zones) — 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. Eleocharis acicularis is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for eleocharis acicularis 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 eleocharis acicularis go outside or overwinter — and where?

Plant it out within USDA 5-10 (cold-tolerant aquatic; grown indoors in aquaria and outdoors in ponds in mild zones) 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 eleocharis acicularis can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Eleocharis acicularis hardiness — frequently asked questions

Is eleocharis acicularis cold hardy?

Yes — eleocharis acicularis is genuinely cold hardy. Rated RHS H6 and USDA 5-10 (cold-tolerant aquatic; grown indoors in aquaria and outdoors in ponds in mild zones), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Eleocharis acicularis is hardy across USDA 5-10 (cold-tolerant aquatic; grown indoors in aquaria and outdoors in ponds in mild zones); 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 eleocharis acicularis can survive?

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

What hardiness zone is eleocharis acicularis?

Eleocharis acicularis is rated USDA 5-10 (cold-tolerant aquatic; grown indoors in aquaria and outdoors in ponds in mild zones) and RHS H6 — Hardy throughout the UK and northern Europe.

Can eleocharis acicularis survive winter outside?

Plant it out within USDA 5-10 (cold-tolerant aquatic; grown indoors in aquaria and outdoors in ponds in mild zones) 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 eleocharis acicularis 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.