Onions are not roots, even though they grow underground.


The layered sphere we call onion is a bulb. Edible onions form when shortened underground stems are surrounded by fleshy leaves, called scales. People have been growing onions for 7,000 years.


Onions are members of the Allium family, which includes leeks, chives, and garlic. All of these crops are best planted late summer and early fall. One of the nicest things about growing your own onions is that they can be eaten at any stage of development. Early green shoots are called scallions, or spring onions, while mid-stage development crops are called summer onions. Onions are a cool weather crop. Hot weather will cause onions (Allium cepa) to go to seed, or bolt.

Onion varieties

​There are three common varieties of onion: white, yellow, and red. White and yellow onions are commonly sautéed or caramelized. This releases sugars that make onions taste sweet. Red onions are more often used fresh, in salads and when grilling. Onions are also classified according to the number of day-hours it takes to trigger the development of a bulb:

• long-day (L) onions - need 14 hours of daylight or more, planted late winter, are best suited for colder regions
• indeterminate-day (I) onions - need 12 to 13 hours, planted in fall, may work in warmer regions
• short-day (S) onions - need 11 to 12 hours, best choice for warmer regions

Some onions have been bred to be smaller. These are called boiler, pickler, or pearl onions. The term “pearl onion’ is incorrect because pearl onions are an entirely different species. True pearl onions are more closely related to leeks, than to common onions, and they do not have layers, more similar to garlic.

Leeks have a nice delicate flavor, but they can get pretty pricey in the grocery store. Luckily for us, they are easy to grow!


Unlike other members of the Allium family, such as garlic and onions, leeks do not form bulbs underground. Instead, leeks grow an edible stem that can be up to 2 inches in diameter. Like garlic, the leaves are flat (onion leaves are tubes). Leeks are commonly paired with potatoes, but they can also be steamed, roasted, or baked to stand on their own.

Leek cultivars

There are two basic types of leeks. Short-season leeks are planted in spring and harvested in late summer and early fall. Hardy long-season leeks are also planted in spring, in the north, but not until late summer in warmer areas. These leeks are not ready for harvesting for at least 100 days, which means they are ready for use through winter.


How to grow leeks

Leeks are biennial plants that are grown as annuals. You can start leeks from seed or by replanting the white base of an existing leek. If you use the base of a leek purchased from the grocery store, be aware that you may be introducing destructive pathogens into your garden.


The base should be planted much deeper than you might expect: 4 to 6" deep. This is how part of the stem stays white, because it is blanched underground. Blanching means keeping certain parts of a plant white by blocking sunlight. 


If you use seeds, plant them 1/2" deep and 6" apart. If you start seeds indoors, be sure to harden them off before planting them in the ground or in tall containers outside. You can also buy seedlings from your local garden store, but they will need to be gently untangled from each other before replanting - they look like unmown grass in the pot. Seedlings should then be transplanted deeper into the soil than they were, up to where the green stems begin, for a longer, more drought resistant edible. Once the seedlings are as big around as a pencil, bank soil or mulch around each plant to continue blanching the base. 


Leeks prefer cooler temperatures, so fall and winter are the best time to grow leeks in areas with hot summers. Leeks enjoy full sun and well-drained soil, but the two components that make the biggest difference in growing leeks are water and nitrogen. Leeks are heavy feeders, so planting them near peas or beans will provide an extra boost of nitrogen early in the growing process, followed with aged compost. Leeks have shallow roots so regular watering is needed for plants to reach full size. Water stress will significantly reduce yields. The soil should be moistened to a depth of 18 inches every week. Mulching around plants can reduce weeds, add nutrients, and cut water needs.


Onion maggots, onion rust, aphids, thrips, and onion white rot are the most common problems encountered when growing leeks.

The crisp, slender stalks of scallions are easy to grow and they take up very little space in a garden or on a windowsill.


Scallions, also known as green onions or spring onions, can either be immature onions before they set bulbs (spring onions), or a specific variety of Allium that never forms significant bulbs.

Scallions in the garden

Scallions can be grown in window boxes, indoor planting containers, hanging planters, or in the ground. They can be grown in full sun or used in shade gardening. The spiky forms of newly growing scallions add a pretty accent to many plantings.


​How to grow scallions

Seeds can be started at any time of year and seedlings can be grown indoors or out. Seeds should be heavily planted, 1/2" deep. Scallions can grown in clumps, so there is no need to thin transplants. Scallion seeds require moisture to germinate and they can take a month to get started. Keep the soil moist and be patient. Like other onions, scallions have a shallow root system, so proper irrigation and frequent, gentle weeding are important. Scallions are heavy nitrogen feeders, so feed regularly with fish emulsion, blood meal, or alfalfa meal. Planting a new batch of scallion seeds every three weeks will keep you supplied with scallions year round. Also, each time you snip the base off of a scallion, those roots can be replanted to grow a new scallion!


Scallion pests and diseases

Scallions may be attacked by thrips. Thrip damage gives the leaves a white streaked look. Thrips can be reduced by spraying plants with soapy water. If tunnels are found in the underground portion of the plant, it may be onion maggots. Most members of the onion family are susceptible to onion white rot and other fungal diseases, such as onion rust. If nematodes are feeding on the root system, plants will appear stunted or deformed.

Dinner wouldn’t be nearly as delicious without plants from the Allium genus. Ornamental Alliums also attract beneficial insects to your garden. ​​

How to grow Alliums

These shallow-rooted plants prefer soil that holds a lot of organic material and that means adding compost before planting. They will grow just about anywhere, but heavy clay soil can slow their growth. Alliums can be grown in partial shade to full sun. They grow well in raised beds and containers. You can grow chives in a pot on your kitchen windowsill for easy access while cooking!


Growing Alliums from seed can be hit and miss. The plants are slow starters and they don’t handle competition (weeds) very well. You can plant seeds in containers or directly in the garden. Seeds should be sown 1/2” deep and 1/2” apart. Thinned plants can be eaten as scallions.


Another way to plant Alliums is in the form of “sets”. These sets are mature bulbs that can be planted directly in the ground or a container. Follow the package directions for depth and spacing. The only downside to sets is that they tend to bolt. Bolting is the beginning of the going-to-seed process. If you are growing onions, leeks, or garlic, plants that have started bolting should be harvested right away, unless you plan to collect your own seeds.


Garlic and onions are best planted October through January.

Cousin to onions, shallots, chives, and leeks, garlic is a member of the Allium family. So why talk about garlic in the middle of August? Most of us gardeners are currently dealing with an over abundance of tomatoes, zucchini, and cucumbers, but fall will be here before you know it.
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Rather than let your valuable garden real estate go fallow, you can chop up plant material, as plants end their productive cycle, and use this valuable resource to prepare your winter crop beds. Lay the material on top or dig it in a few inches. By the time October rolls around, the worms will have created the perfect growing medium for your garlic.


How to grow garlic

Garlic can be grown in containers, shade gardens, on balconies or windowsills, or in traditional garden rows. As a bulb, it is a resilient plant that can fit into practically any landscape. While you can certainly grow new plants from a garlic purchased at the grocery store, you are better off buying starts from a reputable grower. Grocery store garlic is safe to eat, but it may harbor diseases that can harm future crops for many years.


​Garlic comes in two basic forms: hardneck and softneck. The softneck variety stores better, but the hardneck variety produces bigger cloves that are easier to peel. When you are ready to plant, simply separate the cloves from a garlic and plant them approximately 6" apart and 1" deep, with the root end down and the pointy end up. That's it!

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Garlic lore

Garlic has been cited as a cure-all and demon-repellant, among other questionable attributes, but science has shown that garlic really does repel aphids, cabbageworms, codling moths, Mexican bean beetles, peach borers, and even slugs and snails. In my book, that makes garlic worthwhile simply as a natural pest and disease inhibitor. Of course, I love to eat garlic, so I would plant it anyway!