How to Plant Garlic for Bigger Summer Bulbs

Garlic establishes roots in autumn, overwinters with little top growth, then produces vigorous foliage in spring that feeds bulb enlargement. Planting 2–6 weeks before a reliably hard frost gives cloves roughly 2–3 weeks of steady root growth before the soil freezes, which reduces transplant shock and supports larger bulbs the following summer.

Measure your frost date using local extension data or a nearby weather station; in USDA zones 5–7 that usually falls in late September through October, while zones 8–9 can plant as early as late October or even November if soils warm more slowly. In colder zones (USDA 3–4), aim for closer to 2 weeks before freeze to avoid premature shoot growth.

Soil structure strongly controls bulb size. Dig or double-spade the bed to at least 8–10 inches; use a soil probe or trowel to confirm depth. Incorporate 1.5–2 inches of well-rotted compost per square foot and mix into the top 6 inches to improve tilth and water retention. If your soil is heavy clay, add 25–30% coarse sand or grit and organic matter to reach a loose loam texture.

Test soil pH before amendments. Collect 6–8 cores from the top 6 inches across the planting area, mix for a composite sample, and send it to your extension service. If pH is under 6.0, follow recommendations—commonly 1–2 pounds of garden lime per 100 sq ft—to raise pH; if pH is 7.5 or higher, add sulfur only per extension guidance.

Select seed garlic from reputable suppliers and order 2–4 months before planting. For a 4×8 raised bed you can expect 36–40 cloves at 5 inches spacing; plan 10–20% extra to allow for losses. Avoid supermarket bulbs, which may carry viruses or be treated to prevent sprouting.

Plant cloves point-up 2 inches below the soil surface; planting deeper by 1 inch can delay emergence by 7–10 days but may improve heaving resistance in very cold sites. Space cloves 4–6 inches apart in rows 12 inches apart to allow bulbs to reach 1.5–3 inches diameter; use 6-inch spacing for the largest bulbs.

Step 1: Choose and separate seed stock. Buy certified disease-free seed garlic and store bulbs at 50–60°F until planting. Break bulbs into individual cloves the day before planting; keep the papery tunic intact and discard any soft, shriveled, or discolored cloves.

Step 2: Prepare the bed. Remove perennial weeds and loosen soil to 8–10 inches. Spread 1.5–2 inches of well-rotted compost across the bed (about 1.5–2 cubic feet per 10 sq ft) and fork it into the top 6 inches. Use raised beds 6–10 inches high if drainage is questionable to prevent bulbs from sitting in cold, saturated soil.

Step 3: Mark rows and plant. Chalk a planting line or use a string to keep rows straight at 12 inches apart. Using a trowel or bulb planter, place each clove point-end up at 2 inches deep and 4–6 inches from its neighbor. For a 10-foot row, plan on 20 cloves at 6-inch spacing or up to 30 at 4-inch spacing; keep an extra 10% seed to allow for missed spots.

Step 4: Water and mulch immediately. After planting, give the bed 0.5–1 inch of water to settle soil—use a rain gauge to measure. Apply 2–4 inches of straw, shredded leaves, or coarse bark as mulch; in very wet winters reduce to 1–2 inches to limit rot. In arid regions, apply mulch later (after soil has cooled) so summer moisture isn’t trapped.

Step 5: Winter and spring care. Avoid heavy watering during winter; garlic needs moisture but not saturation. In spring, when shoots reach 4 inches (usually 10–12 weeks after planting), remove about 25% of the mulch so the soil warms faster. Side-dress when shoots are 6–8 inches tall with roughly 1 cup compost or 1/2 cup balanced organic fertilizer per 10 linear feet of row, repeating after 3–4 weeks if growth is pale.

Step 6: Scape removal and midseason management. For hardneck varieties, cut scapes as they begin to curl, usually 3–5 weeks before harvest, to redirect 10–20% more energy to bulb growth. Keep weeds removed for the first 8 weeks; once the canopy closes the competition drops. Provide about 1 inch of water per week during active top growth if rainfall is insufficient—measure with a rain gauge or a tuna can placed in the bed.

Pest and disease control: use floating row cover for the first 6 weeks to reduce thrips and onion maggot egg-laying. Rotate allium crops out of the same bed for at least 3 years to lower white rot and nematode risk. If more than 5% of plants show neck rot, remove and destroy affected plants immediately—do not compost them.

Harvest and curing: plan to harvest 7–9 months after planting (about 210–270 days). Begin checking when the lower 3–4 leaves turn brown. Lift bulbs with a fork raised 6–8 inches from the bulb to avoid cuts, brush off loose soil, and cure in a shaded, ventilated spot at 60–75°F and 40–60% relative humidity for 2–3 weeks. After curing, trim roots to 1/4 inch and cut tops to 1–2 inches or braid softneck varieties; store bulbs at 50–60°F and ~60% humidity.

Aftercare for next season: remove old mulch and incorporate 2–3 inches of compost in fall or early spring. If a soil test shows nitrogen low, apply a small sidedressing (1/4 cup blood meal per 10 linear feet) 2–3 weeks after shoots reach 4 inches, but reduce nitrogen again as bulbs begin to swell to encourage bulb formation rather than excess leaf growth.

Further reading: Which Three Vegetables Should Beginners Plant First? · How to Grow Onions from Sets for Reliable Bulbs
Sources: UMN Extension