Cold hardiness & minimum temperature

Is Mustard Spinach 'Savanna' (Brassica rapa var. perviridis 'Savanna')cold hardy? Hardiness zone & min temp

Also called Savanna mustard spinach, komatsuna cultivar.

More about mustard spinach 'savanna'

About Mustard Spinach 'Savanna'

Brassica rapa var. perviridis 'Savanna' · also called Savanna mustard spinach, komatsuna cultivar · edible

'Savanna' is a vigorous komatsuna (mustard spinach), a fast, leafy Asian green with smooth, glossy dark-green leaves on crisp stems. It tastes milder than mustard and richer than spinach, stands both heat and cold better than true spinach, and is slow to bolt. Crop it as baby leaf in weeks or grow on to full bunches.

Cold limit: USDA 2-11 (grown as a cool-season annual) · RHS H4 (10-25°C)

Watch for — Bolting: Slow to bolt but still runs to seed in prolonged heat or after a cold check followed by warmth. Sow in cool windows and harvest young.

What mustard spinach 'savanna''s hardiness rating actually means

Hardiness works differently for mustard spinach 'savanna': it is grown as a seasonal crop, not overwintered. The question is not "what zone" but "how long is your frost-free growing window". Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 2-11 (grown as a cool-season annual) — 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

As an annual crop, its "minimum temperature" is the first hard frost — that is the end of the plant's life, not a survivable low. Many types are also damaged by light frost (around 0 °C).

Concretely, for mustard spinach 'savanna' as it gets too cold:

Light frost (around 0 to −2 °C) damages or kills tender summer crops outright; cold-hardy types take a few degrees of frost.
The plant does not "survive winter" — its life cycle simply ends, by design, when frost arrives or it finishes cropping.
A surprise late spring frost can also kill young transplants set out too early, before the season even starts.

Can mustard spinach 'savanna' go outside or overwinter — and where?

Time it to your frost dates: sow or plant out after the last spring frost, and aim to harvest before the first autumn frost.
In short-season zones, start it indoors or under cover to stretch the effective growing window.
Hardier crops in this group can be sown for an autumn or overwintered harvest in mild zones — check the specific crop.

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 mustard spinach 'savanna' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Frost protection for borderline mustard spinach 'savanna'

Mustard Spinach 'Savanna' is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Use fleece, cloches or a cold frame at each end of the season to dodge a borderline frost and add growing weeks.
Have row cover ready for an unexpected late spring or early autumn frost.
Know your local last- and first-frost dates and count back the crop’s days-to-maturity to schedule the sowing.

Mustard Spinach 'Savanna' hardiness — frequently asked questions

Is mustard spinach 'savanna' cold hardy?

Hardiness works differently for mustard spinach 'savanna': it is grown as a seasonal crop, not overwintered. The question is not "what zone" but "how long is your frost-free growing window". A seasonal crop, not a perennial. Mustard Spinach 'Savanna' is grown 2-11 (grown as a cool-season annual); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature mustard spinach 'savanna' can survive?

As an annual crop, its "minimum temperature" is the first hard frost — that is the end of the plant's life, not a survivable low. Many types are also damaged by light frost (around 0 °C).

What hardiness zone is mustard spinach 'savanna'?

Mustard Spinach 'Savanna' is rated USDA 2-11 (grown as a cool-season annual) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can mustard spinach 'savanna' survive winter outside?

Time it to your frost dates: sow or plant out after the last spring frost, and aim to harvest before the first autumn frost. In short-season zones, start it indoors or under cover to stretch the effective growing window. Hardier crops in this group can be sown for an autumn or overwintered harvest in mild zones — check the specific crop.

How do I protect mustard spinach 'savanna' from frost?

Use fleece, cloches or a cold frame at each end of the season to dodge a borderline frost and add growing weeks. Have row cover ready for an unexpected late spring or early autumn frost. Know your local last- and first-frost dates and count back the crop’s days-to-maturity to schedule the sowing.