What to plant
Growing Garlic and Onions in Raised Beds
Plant garlic cloves in fall, a few weeks after the first fall frost, and onions in early spring, 2 to 4 weeks before the last frost. Both need 4 to 6 inches between plants and loose, well-drained bed soil.
| Fact | Garlic | Onions |
|---|---|---|
| Plant | Individual cloves, pointed end up | Sets, transplants or seed |
| Timing | 2–4 weeks after first fall frost | 2–4 weeks before last spring frost |
| Planting depth | About 2 in of soil over the tip | Sets 1 in; transplants 1–2 in |
| Spacing | 4–6 in | 4 in for bulbs; 1–2 in for green onions |
| Bed depth | 8–12 in | 8–12 in |
| Harvest | Early to midsummer | Mid to late summer |
| Curing | 2–4 weeks | 2–3 weeks |
When to plant
Garlic needs a cold spell to form proper bulbs, so it goes in during fall. A good target is two to four weeks after your first fall frost, while the soil is still workable and several weeks before it freezes solid. Cloves grow roots before winter, sit quietly through the cold, and resume growing in spring. In mild-winter areas, plant in late fall or early winter.
Onions go in early in spring. Plant sets or transplants two to four weeks before the last frost; they tolerate light frost. If you grow from seed, start it indoors eight to ten weeks before you plan to set the seedlings out.
Spacing and depth
Break garlic heads into cloves just before planting and set each one pointed end up, with about 2 inches of soil over the tip. Space them 4 to 6 inches apart each way; a 4-foot bed holds eight to ten across. Bulb onions need about 4 inches. Plant sets 1 inch deep and transplants 1 to 2 inches, keeping the bulb near the surface. For green onions, crowd them to 1 or 2 inches and pull every other one.
Both crops have shallow, fine roots, so 8 to 12 inches of soil is generous. The raised bed's real benefit is drainage: cloves sitting in wet winter soil rot. See our bed depth guide for setups over clay.
Soil and feeding
Loose soil lets bulbs swell evenly. Fill with a crumbly raised bed soil mix, and aim for a pH of 6.0 to 7.0. Mix an inch of compost and a balanced fertilizer in before planting.
Both crops are heavy nitrogen users while making leaves. Each leaf forms a ring of the bulb, so more leaves mean bigger bulbs. Side-dress garlic when spring growth resumes and again three or four weeks later. Feed onions every two to three weeks after planting. Stop feeding both once bulbs start to swell, or they will store poorly. Keep weeds pulled; their thin, upright leaves cannot shade out competition.
Watering
Give both about an inch of water a week during active spring growth, and more in dry, windy weather. Keep it steady while bulbs are sizing. Then taper off. Stop watering garlic about two weeks before you expect to dig it, and stop watering onions once their tops start falling over. Dry soil at the end helps the outer skins form and protects storage life. A soaker hose under 2 to 3 inches of straw is an easy setup; watering raised garden beds has more.
Crop specifics: fall garlic planting, onion sets vs seed, curing
Fall garlic planting
Buy seed garlic from a garden supplier rather than the grocery store; store garlic may be treated to stop sprouting or poorly suited to your climate. Hardneck types handle cold winters and send up curly scapes in early summer. Softneck types do better in mild climates and keep longer. After the soil cools, mulch the bed with 3 to 4 inches of straw to protect cloves from freeze and thaw cycles.
Onion sets vs seed
Onions form bulbs in response to day length. Short-day varieties suit the South, long-day types the North, and intermediate types the middle. Choose for your latitude or you may get small bulbs. Sets are the easiest start, but large ones tend to bolt; pick sets smaller than about 3/4 inch. Seed and transplants give the widest variety choice and usually store better.
Curing
Cure both after digging. Lay bulbs with tops attached in a single layer, or hang bundles, somewhere shaded, dry and airy for two to four weeks. When necks are tight and skins papery, trim roots and cut stems to an inch.
Harvest
Snap off hardneck scapes when they curl; they are good in stir-fries, and removing them sends more energy to the bulb. Dig garlic when the lower third to half of the leaves have browned, usually in early to midsummer. Loosen the soil with a fork first, since pulling snaps stems. Pull onions once half or more of the tops have flopped over. Store cured bulbs cool and dry, never in the fridge.
Garlic and onions finish by midsummer, leaving room for a fall crop of lettuce. They also make a tidy border around strawberries. Browse our planting ideas for beds for other options.
Common problems
Onions sending up flower stalks
Large sets and cold snaps cause bolting. Use those onions first, since they will not store.
Soft, rotting garlic in spring
Waterlogged soil or fungal rot is the usual cause. Plant only firm, healthy cloves in well-drained beds.
Silvery streaks on leaves
Onion thrips scrape leaf surfaces in hot, dry weather. Spray with water and keep plants evenly watered.
Small bulbs
Wrong day-length type for your area, crowding or weeds. Match varieties to your latitude and thin to 4 inches.