Cold hardiness & minimum temperature

Is Oak Leaf Lettuce (Lactuca sativa 'Oak Leaf')cold hardy? Hardiness zone & min temp

Also called oak leaf lettuce, oakleaf lettuce.

More about oak leaf lettuce

About Oak Leaf Lettuce

Lactuca sativa 'Oak Leaf' · also called oak leaf lettuce, oakleaf lettuce · edible

Oak leaf is a loose-leaf lettuce with soft, lobed, oak-shaped leaves prized for cut-and-come-again harvesting. It is fast, cool-season and shallow-rooted, thriving in moist, fertile soil with steady moisture. Grow it in spring and autumn, sow successionally every two to three weeks, and pick outer leaves to keep plants productive for many weeks.

Cold limit: USDA Annual; grown in zones 2-11 as a cool-season crop · RHS H2 (10-20°C)

Watch for — Bolting in heat: Rising temperatures and long days send plants to seed, turning leaves bitter. Sow in spring and autumn, choose shade in summer, and keep moisture steady to delay flowering.

What oak leaf lettuce's hardiness rating actually means

Oak Leaf Lettuce is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA Annual; grown in zones 2-11 as a cool-season crop — 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 1 to 5 °C — tolerates cold but no real frost. Oak Leaf Lettuce shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for oak leaf lettuce as it gets too cold:

Down to roughly about 1 to 5 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can oak leaf lettuce go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA Annual; grown in zones 2-11 as a cool-season crop or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 oak leaf lettuce can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline oak leaf lettuce

Oak Leaf Lettuce is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Oak Leaf Lettuce hardiness — frequently asked questions

Is oak leaf lettuce cold hardy?

Oak Leaf Lettuce is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA Annual; grown in zones 2-11 as a cool-season crop (and sheltered UK gardens) oak leaf lettuce can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature oak leaf lettuce can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Oak Leaf Lettuce shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is oak leaf lettuce?

Oak Leaf Lettuce is rated USDA Annual; grown in zones 2-11 as a cool-season crop and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can oak leaf lettuce survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA Annual; grown in zones 2-11 as a cool-season crop or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect oak leaf lettuce from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.