Bulb ripening
Onion, shallot and garlic foliage yellowing from the tips downward through midsummer, with the necks softening and the tops eventually folding over. This is the crop finishing, not failing. The bulb has stopped growing and is drawing the last of the leaf back into itself, and the yellowing is the signal to stop watering and lift — which makes it one of the few benign states where recognising it promptly actually changes the harvest.
What brings it on
The end of the bulbing period, which arrives on day length rather than on anything the grower did. Autumn-planted garlic ripens from late June, spring-planted garlic and maincrop onions through July and into August. Yellowing that begins at the leaf tips and works down, on a plant whose bulb has visibly swollen, is ripening; yellowing on a plant with no bulb to speak of is not.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Onions and shallots — harvesting
- Royal Horticultural Society: Garlic — harvesting
Checked 2026-08-13
Usually seen: June, July, August
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Nothing to prevent, and the framing matters more here than usual. The two standard responses to a yellowing crop — water it and feed it — are both actively harmful to a ripening allium. Late nitrogen produces soft growth that will not store, and late watering swells the bulb into a split skin and invites neck rot in the sack.
source
GrowingHQ editorial positionhigh confidence
A judgement about what the differential is allowed to conclude for a maturing crop, rather than a horticultural fact, so it is recorded as editorial.
- GrowingHQ editorial synthesis — GrowingHQ
Checked 2026-08-13
Dealing with it once it is there
- Stop watering and feeding once the tops start to go over, and lift within a fortnight rather than waiting for every leaf to yellow. Loosen the bulbs with a fork and leave them somewhere dry and airy for two to three weeks until the skins rustle and the necks are papery.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Onions and shallots — harvesting and storing
Checked 2026-08-13
- Do not bend the tops over by hand to hurry it along. The practice is traditional and repeatedly tested against doing nothing; it brings the harvest forward by a few days and consistently produces bulbs that store less well.
Horticultural consensusDepends on conditionsmoderate confidence
Applies when: Worth doing only where an unripened crop must be cleared before a hard deadline, and at a known cost to storage life.
- Agriculture and Horticulture Development Board — AHDB: Alliums — crop maturity
Checked 2026-08-13
What it affects
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.
Plant-specific guides
Where this is one of several causes that look alike on a particular plant, GrowingHQ publishes the differential rather than the general answer.