Cold-hardy annuals can be sown or transplanted before the last spring frost
Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
Cold hardiness. Hardy crops tolerate hard frost and half-hardy crops tolerate light frost, so they can occupy the ground weeks before frost-tender crops are allowed in. The offset is measured from the last spring frost.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
… withstand freezing temperatures and hard frosts without injury
As early as 2-4 weeks before the date of the average last spring frost
Plus 2 working notes on how the sources were read. Every note is in the data download.
Where this rule stops
For spring sowing only. The three- and two-week leads sit inside Colorado State's planting table (hardy 2 to 4 weeks, half-hardy 0 to 2 weeks before the last frost). The two-week lead is that table's earliest edge, so in a cold spring wait a little longer.
Plants it applies to · 68
Fruiting vegetables · 14, Salad & greens · 12, Roots & tubers · 9, Beans & peas · 9, Herbs · 7, Flowers · 7, Cover crops & soil builders · 7, Onions & garlic · 3
Fruiting vegetables · 14
+6 moreShow fewer
Salad & greens · 12
+4 moreShow fewer
Roots & tubers · 9
Cover crops & soil builders · 7
Read next
- Understanding your frost datesYour last and first frost dates are the clock the whole garden runs on. What they mean, why they're a probability, and how they decide when each crop can go out.
- How to read a planting calendarA planting chart that says "sow in April" is wrong for most of the country. The skill worth having is reading any calendar as an offset from your own frost dates. Here's how, at both ends of the season.
- Starting seeds indoorsWhich crops need a head start, how many weeks before your last frost to sow them, and the list of what you should sow straight in the ground instead.
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Advice on what to do added
- Sources updated
- Details updated
- Wording made clearer
- A person read the sources and confirmed it
- Sources updated
- Added to the rules
More ways Milpa can help
When do I plant? · What grows well together? · Plan my garden · What can I plant now? · Something wrong in the garden? · Keep a garden diary · Heard a tip?
Cite this page
Milpa Gardens. “Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself.” Evidence grade: Promising. https://milpa.garden/rules/cold-hardy-annuals-can-be-sown-transplanted/
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
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How we grade evidence
- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
- Promising
- The mechanism is named and the literature backs it. A few questions are still open.
- A good hunch
- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
- Contested
- The evidence points both ways, or no study has tested it, so the planner does not enforce it.
- Refuted
- The claim did not survive its sources. It is kept so the folklore can be answered.