How to Plant and Grow Garlic (Allium Sativum)

Woman trimming fresh garlic harvest

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A close relative of the onion, garlic (Allium sativum) is an edible, bulbous plant that has been cultivated for several thousand years. It is more popular today than ever and, with over 600 sub-varieties available, there is ample room for gourmet garlic growers to carve out a niche. For the home gardener, it is quite easy to grow a year's supply, and you can give your leftover crop to friends and neighbors.

Varieties

The many sub-varieties of garlic fall into two basic categories: hardneck and softneck.

Hardneck garlic (Allium sativum var. ophioscorodon) includes the varieties porcelain garlic, rocambole garlic, and purple stripe garlic. The softneck garlic (Allium satvum var. sativum) varieties include artichoke garlic, silverskin garlic, and creole garlic.

A few basic differences exist between the two categories of garlic.: softneck varieties are best grown in warm climates, while hardneck is the garlic of choice for northern garlic growers. Softneck garlic stores and travels better than hardneck garlic. It also has a stronger flavor and generally speaking, produces larger cloves. If you want a milder garlic taste, try elephant garlic—which is actually more closely related to leeks than it is to true garlic.

Planting and Growing

Garlic is planted either in the fall or the spring, depending on your climate. In the north, plant garlic in the fall. In warmer climates, it is best to plant garlic in early spring, though seed garlic must be chilled first to break it out of its dormant state. Garlic prefers loose loamy soil with plenty of organic matter.

  1. Separate the garlic bulbs into individual cloves right before planting, leaving the papery layer around each clove. Choose the largest cloves for planting and use the smaller ones for cooking or preserving.
  2. Plant the cloves 2 inches deep if you plan to mulch and 3 to 4 inches deep if you do not plan to mulch.
  3. Be sure to place each clove into its planting hole with the pointy tip facing up and the basal/root end facing down.
  4. Space the cloves 4 to 6 inches apart in rows spaced 18 to 24 inches apart. Commercial growers often plant the cloves and rows closer together; this leads to smaller bulbs but an overall higher yield in terms of garlic per square foot of garden.
  5. Fill the planting hole with soil or vermiculite and pat down gently.
  6. Water lightly – cloves could rot if the soil is too wet and soggy 

Watering and Mulching

keep soil evenly moist through the first part of the growing season, but allow the soil to go dry for two or three weeks before harvesting. If conditions are too wet near harvest time, mold can grow.

Mulching your garlic with straw, hay, swamp grass, reeds, or chopped leaves or plastic can be very helpful in some circumstances, though it is not recommended in wet climates. Mulch can protect against winter kill in cold climates, and in hot climates, It helps moderate soil temperatures and conserves soil moisture.

Good mulch can also help keep weeds in check. Weeds can easily outcompete young garlic plants, so be sure to keep the plot well-weeded.

Pests and Problems

Extreme temperatures can damage your garlic crop as well as the following issues:

  • White rot fungus: This disease, caused by the Sclerotium cepivorum fungus, is the most serious disease of garlic, and it can also strike all Allium crops, including onions. White rot-infected garlic plants have leaves that turn yellow and plants that wilt and partially die back. As the roots rot, infected plants uproot easily. This disease typically develops from the middle of the season up to harvest. Be sure you obtain cloves from certified disease-free stock because once a field has been infected with white-rot fungus, it can take decades for the infection to completely clear.
  • Nematodes: These microscopic pests, Ditylenchus dipaci, are another chronic problem for garlic. These tiny worm-like creatures live inside the garlic plant itself, eating it while reproducing. Nematodes do not need water to survive and they can live in the surrounding soil for several years. Nematode infestation can build up for several seasons without much damage, and then strike and take out an entire crop. To control nematodes, make efforts to plant clean stock, inspect growing plants frequently, and remove any plants that look diseased.
  • Onion thrips: Thrips are the most common insect to plague garlic. Thrips have rasping-sucking mouth parts that first damage the leaves then suck up the seeping plant fluid. Severe damage can cause the garlic plant to wilt and die. The leaf wounds can create entry points for other diseases. To control thrips, keep areas free of moist, wet mulch that provides breeding areas, and trap the insects with sticky traps.

Harvesting

As it grows, hardneck garlic produces a curly green flower stalk called a scape. Harvest garlic scapes as soon as you notice them growing so that the plant concentrates its energy into growing a larger bulb rather than a flower stalk.

It's time to harvest your garlic when 1/2 to 3/4 of the bottom leaves have turned brown. This usually happens by mid- to late-summer—July and August for most areas. Dig up a test bulb or two to determine maturity. The garlic bulb should be well-wrapped but not split.

To harvest garlic, push a garden fork straight down into the soil about 6-8” away from the plant. Angle the fork so that it goes under the bulb and lifts it out of the ground. Don’t pull the bulb out by its leaves, or you risk breaking the bulb off. Use caution, as garlic bruises easily.

Storing and Preserving

You can eat garlic fresh out of the ground, but if you want to store it for winter, you must cure it first.

In warm sunny climates, garlic can be left in the field to dry, but it should be covered with leaves to prevent sunburn. In cooler climates, place garlic in a dark place with good air circulation for 2 to 3 weeks after harvest to allow it to cure.

  • For softneck garlic, you can braid ropes of bulbs and stems and hang them to dry.
  • For hardneck garlic, trim stems to one inch above the bulb then place in a dark, well-ventilated location.

After curing, garlic will keep for 6 to 12 months when stored in optimal conditions. Store garlic where it will have good air circulation, 65 to 70 percent humidity, and a temperature of 35 to 50 degrees Fahrenheit.

Propagation

Garlic is propagated by planting individual cloves separated from bulbs or by using bulbils—the tiny undivided bulbs found in the scapes of hardneck garlic. Propagating garlic using bulbils can be much more effective than planting cloves. If you are planting cloves, save 15 to 20 percent of your crop, making sure to use only truly disease-free bulbs for planting next season.

There are many more bulbils than cloves, making it easier to build up your planting stock, and since bulbils are above ground, there is less chance of soil-borne disease. Plant them just like you would cloves. If you are growing bulbils for seed, allow the garlic scape to grow—they are edible and delicious.