Row cover keeps pests off young crops
Row cover keeps pests off young crops; lift it at bloom for insect-pollinated ones
As recorded: A lightweight fabric floating row cover laid over a bed at planting keeps flying and egg-laying pests off the crop through its vulnerable early stage (flea beetles, cabbage moths and loopers, cucumber beetles and squash bugs, and the root-maggot flies of cabbage, onion, and carrot). It must come off at flowering for any crop that needs an insect to set fruit, or it excludes the pollinator too.
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
Floating row cover is a gauze-like spun sheet laid loosely over the crop and sealed at its edges to the soil, and it stops damage by physical exclusion (the adult insect cannot reach the plant to feed or lay eggs), so the barrier must be continuous from planting, before the pests arrive, with its edges buried against a walking insect; because the same closed barrier also shuts out the bee, a crop whose fruit depends on insect pollination has to be uncovered once its flowers open.
What to do about it
Cover the bed at planting with the crop still small, drape the fabric loosely with slack to grow into, and bury or weight every edge so the perimeter is sealed. Leave it on through the early weeks when the pest is active. For a crop that needs insect pollination to fruit (squash, cucumber, melon, pumpkin), remove the cover once female flowers begin to bloom so pollinators can reach them; leafy greens, roots, brassicas grown for heads, and self- or wind-pollinated crops can stay covered to harvest. Where the target pest overwinters in the soil under the bed (root maggots, flea beetles, Colorado potato beetle), cover a bed that did NOT grow the same crop, or the pest emerges trapped inside.
How much it matters: No exclusion percentage is stated or invented. The protection is near-total while the barrier is intact and sealed and nil wherever there is a gap or once it is removed at flowering; because the outcome depends on timing and edge-sealing, both the gardener's to control, the rule advises.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
For insect pollinated vegetables, like the nightshades ... and cucurbits ..., row cover should be removed when female flowers bloom so as to allow pollination to occur.
Some pests overwinter in the soil near host plants, emerging the following spring under a cover. (Examples include the adult flies of root maggots, flea beetles, and Colorado potato beetles.)
Read next
- What's eating my plants? Reading the damage before you actMatch the holes, the trails and the cut stems to the culprit first, then use the fix that works. Most of it isn't spray, and some damage costs nothing.
- Cold frames and low tunnels for extra weeks of seasonWhat cold frames, low tunnels and row covers really buy: the degrees, the weeks, and the venting chore that decides everything. Plus what to grow under each.
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
Cite this page
Milpa Gardens. "Row cover keeps pests off young crops; lift it at bloom for insect-pollinated ones." Evidence grade: Promising. https://milpa.garden/rules/lightweight-fabric-floating-row-cover-laid-over/
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