A Plain Language Guide Growing Fresh Market Onions, Garlic, and Leeks A. C. Newenhouse The Wisconsin Farm Center has more information about services to help beginning farmers. To find this information on the internet look under the heading Farming and Agriculture at http://datcp.state.wi.us/. Your local county Extension office also has more information for fresh market farmers. Go to http://www.csrees.usda.gov/Extension/. Click on your state and then your county to find the Extension office near you. i Plant Description ..............................................................................1 Onions ......................................................................................................................2 Index Garlic ........................................................................................................................4 Elephant Garlic ........................................................................................................4 Leeks ........................................................................................................................5 Chives ......................................................................................................................5 Wild leek or Ramp ....................................................................................................6 Site Selection ....................................................................................6 Variety Selection................................................................................7 Planting and Care ..............................................................................8 Starting Seeds ..........................................................................................................9 Soil preparation ......................................................................................................10 Raised Beds............................................................................................................11 Seeding in the field ................................................................................................11 Transplanting ..........................................................................................................11 Onion growth ..........................................................................................................12 Garlic growth ..........................................................................................................12 Elephant garlic growth ............................................................................................14 Leek growth ............................................................................................................14 Wild leek or ramp growth ........................................................................................15 Soils and Nutrient Management ....................................................16 Soil pH ....................................................................................................................16 Fertilizer needs ......................................................................................................17 Irrigation..........................................................................................18 Harvest, Handling, and Storage......................................................19 Onions ....................................................................................................................19 Garlic ......................................................................................................................20 Elephant garlic ........................................................................................................21 Leeks ......................................................................................................................21 Wild leek or ramps ..................................................................................................21 Preventing Stress on Your Body ....................................................22 Weed Management ..........................................................................23 Pest and Disease Management........................................................25 Botrytis leaf blight....................................................................................................26 Botrytis neck rot ......................................................................................................26 Downy mildew ........................................................................................................26 ii Onion smut..............................................................................................................28 Purple blotch ..........................................................................................................29 Soft rot ....................................................................................................................29 Insect Management..........................................................................30 Aster leafhopper......................................................................................................30 Black cutworm ........................................................................................................32 Index Onion maggot ........................................................................................................32 Onion thrips ............................................................................................................33 1 Onions, garlic, and leek are good Onions, garlic, and leeks have been crops to grow for the farmers market used in cooking for at least 4000 Plant Description because you can sell them at different years in middle Asia, Egypt, and the stages of growth, their harvest dates Mediterranean. Drawings of onions are flexible, and you can store them. have been found on tombs in Egypt You can also make products such as from 2800 BC. Leeks are native to the garlic braids to add value to your crop. eastern Mediterranean. Onions and garlic are basic cooking Most plants in the Allium family ingredients and are healthy to eat. If (alliums) are cool season biennials. you grow different types of onions Biennial plants produce leaves the such as sweet onions, fall green first year and flowers the second year. onions, and storage onions, you can They live only two years. Farmers harvest from early spring through late grow alliums as annual vegetables fall. without letting them produce flowers. Plant Description Alliums have shallow fibrous roots that grow down from a plate at the Onions, garlic, leeks, chives, and base of the plant. Allium leaves are shallots are all members of the Allium thick and fleshy. Leaves grow out from or onion family. These plants are the base of the plant. Leaves can be native to central Asia. The typical shaped like a tube or be slightly flat. onion or garlic flavor comes from an enzyme that acts with sulfur in the soil Allium plants form bulbs. The scales and makes sulfur compounds in the that make bulbs are actually the thick plant. These sulfur compounds are part at the base of each leaf. Plants anti-microbial and anti-fungal and give form bulbs when they have the right onions medicinal value. Eating raw day length and temperature. When onions helps thin the blood. the plant has grown until the right day 2 length, then high temperature will onions under short day conditions you make it start to form a bulb. Plants will get leaves but not bulbs. If you with more leaves at that time form a grow short-day onions under long-day bigger bulb and produce higher yield. conditions you will get small bulbs Plant early to get the most leaves and that start to form early. Farmers in the largest bulbs. upper Midwest usually grow long-day onions. Long-day onions need at least When temperatures fall below 50°F, 14 hours of daylength before they stems get longer and flowering start to form bulbs. begins. Flowers have both male and female flower parts and are pollinated Short day onions such as Bermuda by insects. The flower is shaped like a onions won’t grow in areas at more ball or an “umbel” and is made up of than 30° latitude. many individual flowers together. You can grow long day onions to eat fresh or to store and keep for a long time. Onions that are called “sweet” are usually grown to eat fresh. Plant Description Onions that are called “dry” can usually be stored for a long time. Long-day onions usually have sharper flavor than short-day onions. Some Onion flower - ball factors change the sharpness of an onion’s flavor. These factors are Dr. Michael Havey, haveylab.hort.wisc.edu variety, temperature, soil pH, and soil moisture. Onions can be round, slightly flat, or cone-shaped. Onion skin can be white, yellow, brown, red, or purple. Onion skin is used to dye cloth. If onions grow quickly in a short time their bulbs can become longer. If Onion flower - umbel onions grow slowly over a long time © Smithsonian Institution - W.S. Justice their bulbs are larger. If side bulbs sprout from inside the base of several Onions leaves then you will see many smaller Onion varieties (Allium cepa var cepa) bulbs form. are either short day, intermediate, or long day depending on the number of Green onions (Allium cepa var cepa) hours of light they need to start are immature onions that you harvest forming bulbs. If you grow long-day before the bulb forms. 3 Scallions or “bunching onions” Shallots (Allium cepa var. (Allium