AMES, Iowa -- Garlic (Allium sativum) is an important addition to many recipes and one of only a very few vegetables grown in Iowa that are started in the fall and harvested the following year. Iowa State University Extension and Outreach horticulturists offer tips for planting and caring for these popular edible bulbs.
What types of garlic should I grow?
Garlic is distinguished from its other close family members like onions, chives, shallots and leeks, by its flat leaves and clove-like bulbs, which contain several small scales or cloves enclosed in a white or purplish parchment-like sheath.
Garlic cultivars are classified as either hardneck or softneck. Hardneck cultivars (Allium sativum var. ophioscorodon) produce cloves that surround the base of a hard flower stalk. They grow well in Iowa, but do not store as well as softneck cultivars. Hardneck cultivars are divided into three common types, Rocambole (6-11 cloves; twisted scapes), Purple Stripe (8-12 cloves), and Porcelain (4 large symmetric cloves). Suitable cultivars for Iowa gardens include ‘Asian Tempest’, ‘German Red’, ‘Merrifield Rocambole’, ‘Music’, and ‘Spanish Roja Rocambole’.
Softneck cultivars (Allium sativum var. sativum) look more like the garlic bulbs we see in the grocery stores. While many perform better in warmer climates, there are some softneck cultivars that are suitable for Iowa’s colder temperatures. They usually do not grow a flower stalk. Softneck cultivars are generally more productive and easier to store than hardneck cultivars. Softneck cultivars suitable for Iowa gardens include ‘Inchellium Red’, ‘New York White’, and ‘Susanville’.
When and where should I plant garlic?
Grow garlic in well-drained, fertile soils that are high in organic matter. Amend heavy clay soils with compost or well-rotted manure before planting to prevent misshapen bulbs. Garlic does not grow well or reliably from seed. Plant cloves obtained from garden centers or mail-order companies in fall (October to early November). Do not plant garlic cloves purchased from grocery stores as these are usually softneck cultivars from warmer regions that are not well adapted to Iowa’s climate.
Plant large cloves 1 to 1.5 inches deep with the pointed side up, 3 to 5 inches apart within rows that are spaced 18 to 24 inches apart. Start with large cloves, as they produce larger bulbs. Fall-planted garlic should be mulched in November with a 4- to 6-inch-layer of weed-seed-free straw to help prevent winter injury. In early spring, move the straw to between the rows to allow the garlic foliage to emerge.
How do I grow and care for garlic?
Garlic requires more fertilizer than many vegetables. Apply and incorporate 1 to 2 pounds of an all-purpose garden fertilizer, such as 10-10-10, per 100 square feet of garden area prior to planting. Lightly incorporate one additional pound per 100-foot row of the all-purpose garden fertilizer in a band 4 inches to the side of the developing plants 3 to 4 weeks after plants emerge in the spring.
Garlic requires 1 inch of water each week. Irrigate garlic once a week during dry weather. Stop irrigating in late July to allow the foliage to die down prior to harvest. This also helps reduce disease spread and staining of the paper covering on the bulb.
Garlic has a shallow root system. Control weeds with shallow cultivation or by applying a mulch, such as straw or grass clippings, between rows. Mulch will also help to conserve soil moisture.
When and how do I harvest, dry, and store garlic?
Harvest garlic when the foliage begins to dry. In Iowa, garlic is usually harvested in July or August. Carefully dig the bulbs with a garden fork or shovel.
Dry garlic in a warm, dry, well-ventilated location. Place the garlic on an elevated wire screen or slotted tray to promote drying.
When the tops have dried, cut off the dry foliage 1 inch above the bulbs. Also, trim off the roots and brush off any loose soil. Place the bulbs in a mesh bag or open crate and store in a cool (32 to 40 F), dry (65-70% relative humidity) area. Garlic can be stored for three to six months if properly dried and stored. An alternate way to store garlic is to braid the foliage together immediately after harvest, dry and then hang the braided garlic in a cool, dry location.
What are garlic scapes and what should I do with them?
Hardneck cultivars of garlic will produce a scape or flower stalk from the center of the leaves in mid- to late-May. Removing the scape is advised, as it will help the bulb grow larger because the plant will put energy into bulb production rather than flower and seed production.
Harvest garlic scapes when they are immature, are fully extended above the leaves, and have begun to curl but before the stalk straightens and the bulbous end opens to reveal flower buds. Cut the stalk off as low as you can without cutting off any leaves.
Young scapes can be used in cooking to provide mild garlic flavor when chopped and added to eggs, salads, stir-fries, or pickles or to make pesto. They are also attractive additions to floral arrangements.
Photo Credit: garlic on a wooden board, by bit24/stock.adobe.com.