Lettuce and spinach do better in a taller neighbor's summer shade
As recorded: Heat bolters that tolerate part sun, such as lettuce and spinach, are better off in the computed summer shadow of a taller neighbor than in open sun.
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
Leaf temperature. Shade from a taller crop lowers the leaf and soil temperature of the greens beneath it, and high summer temperature is the trigger that sends these species to seed and turns them bitter.
What to do about it
Put a tall, shade-casting crop such as sweet corn or a staked tomato on the sun side of your greens so its shadow reaches them by midsummer. A 30 to 50 percent shade cloth does the same job where no tall crop fits.
The evidence
Evidence: checked against 5 sources in the research-based literature.
The 5 sources
Increasing day-length and high summer temperatures usually cause seedstalk formation (bolting) and bitter flavor
Shade-tolerant species, such as lettuce, spinach, and celery, can be planted in the shadow of taller crops, like beans or squash.
A good investment if you want to grow lettuce and other leafy greens all through the summer is a shade cloth
High summer temperatures usually cause seed stalk formation (bolting) and bitter flavor
Plant spinach in early spring to avoid high temperatures and long days, which cause the plants to bolt, or form flower stalks.
Plant teams that rest on it
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Wording made clearer
- Wording made clearer
- Added to the rules
Plan a bed with Summer shade salad ›
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Cite this page
Milpa Gardens. “Lettuce and spinach do better in a taller neighbor's summer shade.” Evidence grade: Promising. https://milpa.garden/rules/heat-bolters-that-tolerate-part-sun-such/
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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.