Where frost is rare, sow so the crop grows through months that suit it.
As recorded: Where frost does not end the season, a crop does best sown so that the months it grows through average between its lowest and highest temperature, long enough for it to reach harvest. Where every month is warmer than a cool-season crop's highest, its coolest months are its best chance, with care.
A good hunch A person has checked it against its sources. If you skip this, you lose real yield. The planner suggests it.
How it works
A crop grows and makes its harvest within a band of warmth: in months colder than its band it grows too slowly to finish, and in months hotter than it a cool-season crop bolts and turns bitter while a warm-season crop drops its flowers.
What to do about it
Sow in the months the app names. Outside them, grow a crop whose months they are, or a variety bred for the heat or the cool.
The evidence
Evidence: checked against 9 sources in the research-based literature.
The 9 sources
Optimum Temperatures for Different Vegetables
Average monthly temperatures for cool-season crops during their growing period: 60-65F. This includes, carrots, parsnips, spinach, lettuce, broccoli, and garlic to name a few.
Group D: These vegetables thrive in areas where the mean monthly temperatures range between 15 and 18°C. They are intolerant to temperatures between 21 and 24°C, and tolerate weak frosts. This group includes spinach, lettuce, broccoli, beetroot, Brussels sprout, cabbage, radish, rhubarb and watercress.
Summer. As temperatures rise, cool-season crops bolt and become bitter.
Night temperatures below 60° F. and above 75° F. or day temperatures above 95° F. can cause pepper flowers and small fruits to drop.
In the Top End climate lettuce plantings are restricted to the cooler months from April till July. Hot weather makes the plants to bolt, as they do not form a head but flower instead.
Cabbages are a cool climate crop and their planting in the Top End is restricted from the end of March through to July.
Onions can be grown only in the cooler months in the Top End, which limits planting from the end of March to the end of May.
Leaf types grow well in Florida; grow crisphead type only in coolest months.
Where this rule stops
It reads each month's normal mean, the average of its normal daily high and low, so a cold snap or a heat wave is not seen. Its crop limits come from one table that does not say what its numbers measure; they are read as monthly averages, so every date it gives is an estimate. It does not read the wet season.
Plants it applies to · 37
Fruiting vegetables · 12, Salad & greens · 10, Roots & tubers · 6, Beans & peas · 4, Onions & garlic · 3, Herbs · 2
Fruiting vegetables · 12
+4 moreShow fewer
Salad & greens · 10
Beans & peas · 4
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Details updated
- Details updated
- Added to the rules
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Cite this page
Milpa Gardens. “Where frost is rare, sow so the crop grows through months that suit it.” Evidence grade: A good hunch. https://milpa.garden/rules/where-frost-does-not-end-season-crop/
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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.