GardenBiennial Root Vegetable · zones 2–11 · 7 varieties
Rutabaga
Brassica napus (Napobrassica group)
Brassicaceae — the same plant family as cabbage, radish, broccoli, cauliflower and 12 more here. Relatives share pests and diseases, which is why rotation plans group by family.
Rutabaga (Brassica napus (Napobrassica group)) is a biennial root vegetable for USDA zones 2–11. It wants full sun and pH 6–6.5 soil, with about 1–2 in of water weekly. It matures in about 90–100 days from sowing. Watch for flea beetles and clubroot. Below: its full sourced profile from 7 extension sources, plus a planting calendar timed to your frost dates.
Typical dates for zone 6b — set your zone or ZIP for yours. This calendar assumes the crop is direct sown. Timing is a guide from the crop's sourced growth stages; confirm with your local frost dates and extension before you sow.
What we will not put a number on
We do not give a feeding rate for this crop, and that is deliberate rather than a gap. The figures published by extension services are pounds of nitrogen per acre for a production field — they do not convert safely to a raised bed or a pot without knowing your soil test and your fertilizer's analysis, and guessing errs toward burning roots. It is also why every chart you find online disagrees with the next one.
We give watering as a depth per week rather than gallons per plant, because that is how it is actually measured and how the published figures are written. A gallons-per-plant number depends on your spacing, your soil and whether the plant is in a pot — so it would look more precise than it is.
Site & soil
- Hardiness zones
- 2–11
- Sun
- Full sun
- Soil pH
- 6–6.5
- Soil texture
- Sandy, Loam, Well drained
- Frost tolerance
- Hardy
No published figure for the temperature frost starts to hurt it, the temperature that would kill it and a heat limit. We looked — where a number is missing here it is missing from the research, not skipped. The crop’s frost and heat tolerance above still applies.
The plant
- Mature height
- 1–2 ft
- Mature spread
- 8–12 in
- Growth rate
- Slowest
- Spacing in row
- 4–8 in
- Between rows
- 18–24 in
- Planting depth
- 0.25–0.5 in
- Container size
- 3–5 gal — low end is the minimum, high end is betterest
- Support
- Self-supportingest
- Grown from
- Direct sow
Water & feeding
- Water needs
- Moderate
- Water per week
- 1–2 in/wk
- Critical water
- Root sizingest
- Feeding
- Moderate
Timing & fruiting
- Days to maturity
- 90–100 days from seed
- Harvest cues
- Root shoulder visible
Planted again for autumn
- South Carolina — Piedmont
- Jul 15 – Sep 30
- South Carolina — Coastal Plain
- Aug 15 – Oct 15
Published by the extension service for its own regions, and quoted here for those regions only — converting them would mean assuming a frost date somewhere else. The chart says when, not whether to sow seed or set out plants, so we do not either. Only South Carolina so far.
- Sow by
- late Jul typical · zone 6b
90 days to maturity from sowing, counted back from the first frost above. Not published for anywhere in particular: it is your own frost date and this crop's own figure, which is why it works wherever you are. A days-to-maturity figure is a catalog number for a good season rather than a promise, and a cold month moves it.
Edible parts per source: root, leaf.
Compiled from the extensions cited below. Which ones actually show up depends on your region — your extension's local list is the last word.
| Variety | Type | Days | Color |
|---|---|---|---|
| American Purple Top Heirloom | Purple Top | 90–100 | Purple |
| Gilfeather Heirloom | White Fleshed | 90–100 | White |
| Helenor | Purple Top | 90–100 | Bicolor |
| Joan | Purple Top | 90–100 | Purple |
| Laurentian Heirloom | Purple Top | 90–100 | Purple |
| Marian | Purple Top | 90–100 | |
| Purple Top Yellow Heirloom | Purple Top | 90–100 | Purple |
- Clemson Cooperative Extension, Home & Garden Information Center
- Johnny's Selected Seeds
- Missouri Botanical Garden
- NC State Extension
- University of Minnesota Extension
- Utah State University Extension
We compile bare facts from these university-extension and horticultural sources, never copied prose. 16 of the 20 values on this page carry a citation. The rest are marked est; hover one and it says why — either nobody publishes a figure we could point at, or a person set it and attached no source. Figures vary with climate and seed source; confirm with your local extension before you buy.
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