Hardneck Garlic Plant Profile

A wicker basket full of garlic scapes
 BruceBlock/GettyImages

Garlic (Allium sativum) is an edible bulb plant closely related to the onion (A. cepa). Like most Allium species, garlic plants send up a flower stalk in late spring or early summer, which will produce flowers if the stalk isn't removed. On the variety known as hardneck garlic (Allium sativum var. ophioscorodon), those stalks are known as garlic scapes, and they are surprisingly tasty and versatile to use in the kitchen. Cutting off the garlic's scape redirects the energy of the plant to produce a larger bulb instead of wasting its efforts on the flower and seed production.

Botanical Name Allium sativum var. ophioscorodon
Common Name Hardneck garlic
Plant Type Edible bulb
Size 12 to 18 in. tall, 9- to 12-in. spread
Sun Exposure Full sun
Soil Type Silty loam
Soil pH Slightly acidic to slightly alkaline (6.0 to 7.5)
Hardiness Zones 3 to 9 (USDA)
Native Area Central Asia, Northeastern Iran
Toxicity Toxic to dogs and cats
Garlic scapes freshly picked
Laura Reid / Getty Images

How to Plant Hardneck Garlic

Unlike many other types of plants, garlic is planted in the fall, goes dormant in the winter, and then begins to grow as the soil warms up during the spring. When growing garlic, plant cloves in the fall about four to six weeks before the first predicted frost.

Plant garlic cloves 4 to 6 inches deep into the soil with the pointed end pointing up, spaced about 6 inches apart. Rows should be spaced about 1 foot apart. Mulch well to protect the plants and retain moisture in the soil. Don't worry if you see the garlic sprouting in the fall—a thick layer of mulch will help protect the plants. When the spring months roll around, keep the garlic bed free from weeds, which can decrease yield by up to half.

Hardneck Garlic Care

Light

Garlic requires six to eight hours of full sunlight per day. However, if you live in an extremely hot climate, the garlic might do well with a bit of partial shade in the afternoon.

Soil

Garlic grows best in a fertile loam or silty loam soil. Once you have planted the garlic, add a layer of mulch to keep weeds at bay. When the ground has frozen, add another heavier layer of mulch to insulate the ground. The soil should be well-draining to avoid rot.

Water

Because of its shallow root system, garlic needs plenty of water and will stop growing if the soil is dry.

Temperature and Humidity

Hardneck garlic tolerates cold winters better than softneck garlic—in fact, it requires cold during the winter to form its bulb. Additionally, if the soil gets too hot, the garlic's roots can stop growing. This plant is best suited for growing in USDA zones 4 to 9.

Fertilizer

Garlic is a heavy-feeding plant, so add compost to the soil when it's first planted, and then fertilize it in the spring by side dressing or broadcasting fertilizer over the whole plant bed. Choose a fertilizer that is high in nitrogen. Finally, fertilize the garlic again around mid-May, right before the bulbs swell, then lay off on the nitrogen-rich food to avoid stunting the bulb's growth.

Is Garlic Toxic?

All members of the Allium genus contain thiosulfate, which is toxic to dogs and cats but not to humans. Thiosulfate is metabolized in dogs and cats in a manner that causes damage to red blood cells, resulting in anemia. It can also cause vomiting, diarrhea, loss of appetite, abdominal pain, depression, and dehydration. However, a pet needs to eat a considerable amount of garlic before serious symptoms are seen.

Hardneck Garlic Varieties

All hardneck garlic varieties produce a flower stem, and the hardneck Rocambole garlic (A. sativum var. ophioscorodon) sends out the curling scapes that gave them the nickname "serpent garlic."

There are many cultivars of hardneck garlic, including 'Porcelain', 'Purple Stripe', 'Marbled Purple Stripe', and 'Glazed Purple Stripe'. The flavor of the scapes can vary considerably from variety to variety, just as with garlic bulbs. Some of the more popularly grown varieties of Rocambole garlic include ‘Carpathian,’ ‘German Red,’ and ‘Spanish Roja.'

Harvesting

When the scapes are just starting to poke up above the leaves, they are tender enough to eat fresh. Garlic scapes get tougher the longer that they grow. Although they twist and turn and look wonderfully exotic as they grow, they become spicier and more fibrous, requiring peeling and some gentle cooking before eating. Ideally, the scapes should be about 10 inches to harvest.

Snapping the scape off with your fingers, as you would with asparagus, will ensure that you get the most tender portion, but cutting them is a bit gentler on the bulb and that is what we're growing the garlic plants for, after all. The cut stem will probably ooze a bit, but that will stop when the sun warms it and seals the cut.

Keep in mind that you do not have to cut the scapes at all. Some gardeners argue that leaving the scapes on results in a garlic bulb that stores longer. As the garlic matures, the scape will straighten out. Tall, straight scapes are a sign that the garlic is ready to be harvested.

Harvesting the garlic bulbs requires careful timing. They are generally ready once the bottom three or four leaves have turned brown while the upper leaves are still green. Carefully dig up the bulbs with leaves intact, using a garden fork, then gently clean off the dirt, rinse the bulbs, and cut the roots off to within 1/4 inch of the bulb. Bundle the bulbs together by the leaves, and cure them in a dry, well-ventilated space for about two weeks. For long-term storage, hang the bundles in a dry space at either room temperature or just above freezing. Don't store them in a refrigerator, as these temperatures will cause the bulbs to begin sending shoots.

Propagating

Hardneck garlic can be propagated using the bulbs you have harvested. A few days before planting, break the bulbs apart into cloves, but keep the papery husk on the individual cloves. Plant garlic cloves 4 to 6 inches deep into the soil with the pointed end pointing up, spaced about 6 inches apart. If planting in rows, space the rows about 1 foot apart.

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Watch Now: Simple Pasta Recipe Using Garlic Scapes

Common Pests and Diseases

Garlic's pungent aroma means its fairly pest-resistant, but it's not entirely free from destructive creatures. All types of garlic and its scapes are susceptible to bulb mites, which can reduce harvest and stunt growth; leaf miners, which damage the scapes; and wheat curl mites, which can cause twisted, stunted growth.

However, the biggest pest problems come from nematodes, which eat both the garlic bulb and the scape, and thrips, which suck the sap from the plant and cause a slow death to the garlic bulb.

If you're comfortable with using commercial pest-control products, apply a pesticide to your plant to control the insects. If you would rather keep pest control more natural, rotate the crops annually, and use sticky traps for thrips.

Article Sources
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  1. Growing Hardneck Garlic. University of Maine Cooperative

  2. Salgado, Bs, et al. Allium Species Poisoning in Dogs and Cats. Journal of Venomous Animals and Toxins Including Tropical Diseases, vol. 17, no. 1, 2011, pp. 4–11., doi:10.1590/s1678-91992011000100002

  3. Bulb Mites. University of California Agriculture and Natural Resources

  4. Nematodes. University of California Agriculture and Natural Resources