When to plant garlic

Why garlic is planted in fall

A garlic clove needs a long spell of cold before it will divide into a new bulb with cloves. This is called vernalization, and it takes roughly six to eight weeks of temperatures below about 40°F, with hardneck types needing the most. Northwest winters provide that easily. Garlic planted in spring, or kept somewhere warm, often grows into a single round bulb with no cloves at all.

Fall planting also gives cloves time to grow roots before the ground gets cold. Aim for a few weeks of rooting before a hard freeze; the green shoots may poke up in fall, and that's fine.

Leaves now, bulb later

Bulb size is set mostly by how much leaf the plant grows before it starts bulbing. Lengthening days and warming weather in late spring switch the plant from making leaves to filling the bulb, and each leaf becomes one of the papery wrappers around it. Anything that grows bigger, healthier leaves by early June, like good soil, steady moisture and spring feeding, means bigger heads.

Feed with a nitrogen fertilizer when growth picks up in early spring and again a few weeks later, then stop by late May. Late nitrogen keeps the plant leafy and delays bulbing.

Soil and water

Garlic wants loose, well-drained soil with a pH of about 6.0 to 7.0 and plenty of compost. Cloves sitting in waterlogged winter soil rot, so raised beds help on heavy clay. Keep the soil moist in dry springs, roughly an inch of water a week, and stop watering about two weeks before harvest so the wrappers dry and tighten.

Scapes

Hardneck garlic sends up a curly flower stalk, the scape, in late spring. Snapping it off once it curls redirects energy into the bulb and generally gives noticeably bigger heads. Scapes are also good to eat, with a mild garlic flavor.

Diseases worth knowing

Rust shows up as orange spots on leaves in wet springs and is mostly cosmetic. The serious one is white rot, a soil fungus that turns roots and bulbs to white, fluffy mush. Its resting bodies survive in soil for 20 years or more, and once a bed has it, garlic and onions can't be grown there. It arrives on infected cloves or in soil carried on tools and boots, so start with clean seed garlic from a reputable grower, and never plant cloves from a bulb that looked soft or moldy.

Harvest, curing and storage

Dig when the lowest three or four leaves have turned brown but five or six are still green, usually late June to mid-July. Each green leaf is a wrapper still protecting the bulb. Wait too long and the wrappers break down and the cloves start to separate, which shortens storage.

Cure whole plants in a shady, airy spot for two to four weeks until the necks are dry and tight, then trim. Store at cool room temperature with moderate humidity. Avoid the fridge: temperatures around 40 to 50°F tell cloves that winter is over and trigger sprouting. Softnecks usually keep six to nine months, hardnecks three to six.