Onions & Garlic In The Home Garden
Onions and garlic are two very popular vegetables grown in the home garden.
Onions are quite hardy and grow best in cool weather, so slips or sets should be planted as soon as the soil may be worked in the spring. Many homeowners will soon start harvesting onions from their gardens.
Onion varieties have different requirements as to the number of hours of daylight required to make a bulb. If the seed catalog lists the onion as "long day," it sets bulbs when it receives 15-16 hours of daylight and is used to produce onions in Northern summers. "Short day" varieties set bulbs with about 12 hours of daylight and are used in the deep South for winter production. Seed of short day varieties started indoors in January should produce a harvest in June. Seedlings or sets of long day varieties set out in April will produce a harvest in August.
Onion types are often grouped according to taste. The two main types of onions are strong-flavored (American) and mild (sometimes called European). Each has three distinct colors, yellow, white, and red. In general, the American onion produces bulbs of smaller size, denser texture, stronger flavor, and better keeping quality than European types. Globe varieties tend to keep longer in storage.
For the best storage onions, direct seed the crop or use transplants. Bulb onions recommended for use in Nebraska include: Yellow Sweet Spanish (short term storage), Copra, Walla Walla Sweet (short term storage), Red Hamburger, and First Edition.
Choose an area with full sun, well drained, loam soil with a pH of 6-7. For bulb production, plant onions in early spring. The number of leaves that form prior to bulbing determine the ultimate onion size.
Since bulbing in each cultivar is triggered by a specific daylength, early planting is the most effective method of increasing bulb size, by allowing more time for leaves to form. If the onions do not grow well before bulb induction, the final bulb size may be smaller than desired.
Place plants or sets 1-6" apart in the rows, and 12-24" between rows. Avoid sets more than ¾ inch in diameter because they are likely to produce seed stalks. (Since onions are biennials, onion sets are botanically prone to going to seed. Planting too early and exposure to cold temperatures also cause seed stalk development and thick elongated necks.)
The shape of the onion bulb is determined both by cultivar selection and the growing depth of the basal plate, a section of compacted stem at the base of the onion from which the leaves and roots grow. If the basal plate is near the surface of the soil, as often occurs when onions are direct seeded, the onion bulbs will be a flat disc shape. Onions sets and plants are usually set deeper in the soil causing the bulbs to be more globe-shaped.
Culture & Weed Control
Due to their shallow root systems, onions compete poorly with weeds; shallow cultivation is necessary. Do not hill up soil on onions, as this can encourage stem rot.
Light mulch will help decrease the number of weeds, as well as conserve soil moisture.
Keep onions evenly moist, but not waterlogged, throughout the growing season especially after bulbs begin enlarging. Even moisture is very important; moisture stress can cause double and/or split bulbs.
Harvesting & Curing
Onions should be harvested when about two-thirds of the tops have fallen over and dried, and the “necks” of the onions have started to dry. A common misconception among gardeners is that if they bend over the onion leaves, while they are still green and growing, it will prevent the leaves from growing so much and “send more energy to the bulbs”, resulting in larger onions. It’s also thought that this practice will make the onions mature faster. Unfortunately, it only succeeds in reducing bulb growth since the leaves, which manufacture carbohydrates stored in the bulbs and increase bulb size, are killed.
Research has shown that optimum flavor and sweetness is achieved if onions are harvest when 80% of the foliage has died back. However, once your onions reach this stage, don’t wait more than one or two weeks to harvest; the bulbs may begin to rot, or grow again and go to seed.
Careful handling is essential during harvest to avoid bruising the onions, which helps prevent storage rot. Onions can be lifted by gently pulling the foliage or by pushing them up with a garden fork inserted below the bulbs. Gently brush remaining soil off the bulbs with a soft brush or gloved hand. After harvest, the bulbs must be “cured” if they will be stored for any length of time.
Curing can be done either in the field or in a protected location away from rain. Field cure onions after harvesting by placing them in rows with the leaves partially covering the bulbs. This helps prevent sunburn or greening. Leave the onions in the field until the outer leaves and neck are completely dry and papery. After curing the onion leaves may be left on and braided, or cut off leaving at least one-inch of the top for storing.
If rain is predicted during the harvest period, onions can be cured in a warm, dry, well-ventilated location out of direct sun. After harvesting and removing excess soil, trim away the foliage, leaving a one-inch section of stem at the neck. Place the onions in single layers, in large, flat trays. Simple trays can be made with lathe strips, leaving one half inch between strips to allow for adequate air circulation. Mesh or burlap bags may also be used. Leave the onions in the trays or bags until the outer leaves and neck are dry and papery.
Only firm bulbs should be kept for storage. Onions that are bruised or have a thick neck should not be stored, but used as soon as possible. Do not store other fruits or vegetables with onions and garlic. Keep the onion storage area temperature between 32-36 ° F, with 60% or less relative humidity for longest storage.
One effective storage method is to place an onion in an old nylon stocking, tie a knot and add another onion. When the stocking is filled, suspend it from the rafters in the storage area.
Garlic is planted from individual cloves in early to mid October so the plants have time to grow roots and a few leaves before fall. Space cloves 3 to 4 inches apart and plant 1 to 2 inches deep, similar to onion sets. Large cloves will produce larger bulbs than smaller cloves.
Harvest the bulbs when the leaves have fallen over naturally, then allow them to dry in a well-ventilated location out of direct sun for a few days. At this point, the remaining leaves can be braided together into strings to finish drying or the bulbs can be placed in an old nylon stocking as for onions.