Garlic is planted in autumn, not spring
Garlic is planted in autumn, not spring. The cloves go in the ground several weeks before it freezes, root, and overwinter. The weeks of winter cold below about 40 °F vernalize the clove, and that cold is what triggers it to form a bulb the following spring as the days lengthen. Planted in spring, garlic misses the cold and bulbs poorly.
As recorded: Garlic is planted in autumn, not spring. The cloves go in the ground several weeks before it freezes, root, and overwinter. The weeks of winter cold below about 40 F vernalize the clove, and that cold is what triggers it to form a bulb the following spring as the days lengthen. Planted in spring, garlic misses the cold and bulbs poorly.
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
A garlic clove will not form a bulb until it has been vernalized, held for roughly six to eight weeks below about 40 °F. The bulb itself does not develop during that cold; it is only induced by it, and forms in spring as days lengthen and temperatures rise. Fall planting delivers the cold naturally over winter with the clove already rooted, so growth resumes early and a full bulb sizes up by early summer. It is the same biennial vernalization that prematurely bolts a spring-sown cool-season crop, but with the sign reversed. There the accumulated cold buttons the plant into an early flower and ruins it; here, in a crop sown in autumn to be harvested as a bulb, that same cold is the intended trigger.
What to do about it
Plant cloves in the fall, roughly late September through November in most regions, several weeks before the ground freezes so they root before winter. Set them pointed end up, about 1 to 3 inches deep and 4 to 6 inches apart, using the largest cloves for the largest bulbs. Once the ground has chilled, mulch with a few inches of weed-free straw to blunt winter heaving and injury. Match the type to the winter. Hard-necked garlics prefer cold-winter regions, and soft-necked are better adapted to mild-winter areas.
How much it matters: No yield figure is stated or estimated. The sources give the vernalization window (about six to eight weeks below 40 °F) and report that the highest yields come from large cloves planted in fall; the penalty for spring planting is poor bulbing and the crop does not fail, and because the timing is entirely the gardener's, the rule only advises.
The evidence
Evidence: checked against 3 sources in the research-based literature.
The 3 sources
Garlic cloves require a period of 6-8 weeks of cool weather after planting (below 40 F) to undergo vernalization ... by low winter temperatures
Plant cloves ... in the fall (October to early November)
Garlic | B=180-210 | 4-6 in
Plants it applies to
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How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Details updated
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- Added to the rules
Cite this page
Milpa Gardens. "Garlic is planted in autumn, not spring. The cloves go in the ground several weeks before it freezes, root, and overwinter. The weeks of winter cold below about 40 °F vernalize the clove, and that cold is what triggers it to form a bulb the following spring as the days lengthen. Planted in spring, garlic misses the cold and bulbs poorly." Evidence grade: Promising. https://milpa.garden/rules/garlic-planted-autumn-not-spring-cloves-go/
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