Garlic: lower leaves turning yellow

What it is likely to be on garlic

1. Bulb ripening

   May be normalvery common on this plant

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Onions and shallots — harvesting
   • Royal Horticultural Society: Garlic — harvesting

   Checked 2026-08-13

   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.

   Points towards it

   • · ripening runs through the whole bed at once, because it is driven by day length rather than by anything local
   • · the outer and lowest leaves go first, each one corresponding to a skin the bulb is laying down
   • · nothing was done to it, which fits a crop arriving at maturity on schedule
   • · a bed or bay crop rather than an indoor one

   Argues against it

   • · ripening happens as the ground dries in midsummer; a saturated bed in July points at root disease instead
   • · the newest central leaves yellowing while the outer ones stay green is the wrong way round for ripening, and suggests the base of the plant is being attacked — this rules it out entirely.

   Check this next

   Check the calendar and the neck rather than the leaves. Onions and garlic ripening in June or July yellow from the leaf tips downward across the whole bed together, the neck just above the bulb goes soft so the tops flop, and there is a swollen bulb underneath — that combination is the harvest signal, and the correct response to it is to stop watering rather than to start.

   What to do now

   Stop watering and feeding, and lift within a fortnight of the tops going over rather than waiting for the leaves to finish. Dry the bulbs somewhere airy and under cover for two or three weeks until the necks are papery, and keep any thick-necked ones for the kitchen rather than the store, because those are the ones that rot first.

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Onions and shallots — harvesting and storing

   Checked 2026-08-13

2. Allium white rot

   Candidate 2occasional on this plant

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Allium white rot
   • Agriculture and Horticulture Development Board — AHDB: Alliums — soil-borne disease

   Checked 2026-08-13

   A soil-borne fungus that rots the base of onions, garlic and leeks, leaving white fluffy growth studded with small black resting bodies. Those resting bodies survive in soil for fifteen years or more, so a plot that gets it stops being a plot for alliums.

   Points towards it

   • · white rot spreads outward from an infested patch, so it takes a group of neighbouring plants and leaves the rest of the row untouched
   • · cool wet soil is what the fungus needs to move from plant to plant
   • · a soil-borne problem of the growing bed

   Argues against it

   • · an entire bed going down together points at ripening or at watering rather than at a fungus spreading from a focus

   Check this next

   Pull up one of the yellowing plants — the affected ones lift with almost no resistance because the roots have gone — and look for black specks the size of poppy seeds embedded in the white fluffy growth on the base. Those sclerotia are the identification, and they are what separates white rot from ordinary rotting: they survive in that soil for fifteen years or more.

   What to do now

   Lift and bin the affected plants with the soil clinging to their roots, and do not compost any of it. Then treat that ground as closed to onions, garlic, shallots and leeks for as long as you garden it — there is no treatment available to a home grower, and container growing in fresh compost is the realistic way to keep growing garlic on an infested plot.

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Allium white rot — control

   Checked 2026-08-13

Narrow it down

This page lists everything at once, which is the right shape for reading and the wrong shape for deciding. The interactive tool asks one question at a time, starting with whichever would separate these causes fastest, and stops as soon as further answers would not help.

Opens with the plant and the symptom already set. Nothing you answer is stored or sent anywhere — the answers live in the address bar and nowhere else.

What this does not cover

These are the causes GrowingHQ holds rules for on garlic — not every cause there is. Where several problems look alike, the honest answer is often that they cannot be told apart by eye, and a page that named one would be guessing. If none of the above fits, the general lower leaves turning yellow page lists causes across all plants, and the Garlic profile lists the problems it is prone to.