My motto is to garden smarter not harder, and growing perennial onions is an easy way to ensure a reliable annual harvest. There are many fuss-free types of perennial onions that provide flavorful bulbs, greens, or stalks. Read on to discover six of my essential perennial onions as well as information on how to plant, grow, and harvest each type.
What are perennial onions?
Regular onions, also called common onions (Allium cepa), are biennial plants that produce leaves the first year followed by flowers and seeds the second year. Gardeners treat common onions as annual vegetables however, and pull the bulbs at the end of the first growing season. Perennial onions, on the other hand, are plants that self-multiply and can be left in the garden for many years. There are numerous types of perennial onions you can grow offering a variety of edible parts and flavors. In my zone 5B garden we enjoy perennial onions almost year-round, especially when they’re planted in a cold frame or greenhouse. These reliable vegetables are perfect for vegetable gardens, food forests, homesteads, urban gardens, as well as ornamental beds. You can even grow perennial onions like chives and potato onions in containers.
Why grow perennial onions?
There are several reasons to consider planting perennial onions, but for me, it’s about reducing work while still enjoying a generous crop of one of my favorite vegetables. The savory flavor of onions is essential in so many dishes and having a steady supply in the garden is a low-maintenance luxury. Also, many perennial onions, like Egyptian walking onions, Welsh onions, and chives have multiple edible parts. Egyptian walking onions have edible bulbs and foliage, Welsh onions have tender leaves and stalks, and chives produce a bumper crop of grassy leaves as well as edible pink flowers.
Perennial onions also make beautiful garden plants, can attract pollinators and beneficial insects, and are bothered by few pests and diseases. Certain types also emerge very early in the spring providing an extra-early crop of fresh greens to kick off the growing season.
Types of perennial onions
There are many types of perennial onions, but these six are my favorites for their ease of cultivation, production, and flavor. Plus, they’re easy to source from online suppliers as well as local garden centres.
Egyptian onions (Allium x proliferum)
Also known as Egyptian walking onion, I first spied this perennial onion in the garden of a friend. The original plant had been tucked into a corner of her vegetable garden but soon ‘walked’ throughout an entire bed! Of course the plants don’t actually walk, but they do spread in a unique way. In late spring stalks emerge from the spiky foliage and are topped with clusters of tiny reddish-purple bulbs, not flowers. When the weight of the topset is heavy enough, the stalk tumbles over to the ground. The bulbs send roots into the soil and the bulb clump establishes in its new spot. That said, Egyptian walking onions, also called tree onions, don’t spread aggressively. It’s very easy to maintain a nice sized stand and extra bulb clusters can be dug up and shared with fellow gardeners. We eat the spring greens which taste like scallions as well as the small bulbs, which have a strong onion flavor. They’re also nice when pickled.
Welsh onions (Allium fistulosum)
Welsh onions are also called bunching onions, Japanese onions, and spring onions and form a dense mass of bright green leaves. This scallion-like plant doesn’t form large bulbs but is grown for its mild-flavored hollow leaves and tender leaf stalks. The name is misleading as this perennial plant originated in China, not Wales, and is enjoyed throughout Asia. It’s hardy in zones 5 to 9 and spreads slowly with the plants growing about two feet tall.
Potato onion (Allium cepa var. aggregatum)
I’ve been growing this reliable perennial onion for over 30 years and enjoy the bulbs as well as the flavorful tops. Potato onions are multiplier onions like shallots and have bulbs that divide and make more bulbs. We use the biggest bulbs in the kitchen and replant the small to medium-sized ones for future crops.
Chives (Allium schoenoprasum)
Chives are one of the easiest types of onions to grow in a garden. They’re generally considered a culinary herb, but we use them so often I think of them as a vegetable. The plants form dense clumps of grassy stalks that have a mild onion flavor. In late spring the plants bloom and the rounded lavender flowers are also edible.
Leeks (Allium porrum)
Did you know that garden leeks are hardy perennials? Typically vegetable gardeners grow them as an annual crop and pull the stalks in autumn and winter. Yet, if you allow leeks to overwinter, they’ll flower the following summer, and then develop small bulbils around the mother plant. These grow into a multi-stemmed clump and can be lifted and replanted or dug up and eaten once they reach a harvestable size. There is another type of perennial leek called multiplier leek but I’ve found it difficult to source and therefore didn’t include it in my list.
Ramps (Allium tricoccum)
Known as wild leeks, ramps are a popular spring forage crop with a savory onion-leek flavor. This vegetable is native to North America and thrives in a woodland setting with fertile moist soil. The slow-spreading plants are harvested for their leaves, although the slender white bulbs are also edible.
Where to plant perennial onions
Most types of onions prefer a site with full sun and fertile, well-draining soil. The exception to this is ramps, which grow best in a food forest or woodland garden where there is some shading. I grow most of my perennial onions in my raised vegetable beds, but have also planted various types in herbs gardens and flower borders. Many, like chives and Egyptian walking onions are beautiful plants that add interest to ornamental gardens.
How to plant perennial onions
Perennial onions are quick and easy to plant in garden beds. Below you’ll find specific planting information for each of my six top perennial onions.
How to plant Egyptian onions
Source bulbils in early spring or autumn from a mail order catalog, garden centre, or gardening friend. Plant each bulbil 1 to 1 1/2 inches deep and 6 inches apart. I dig and plant bulbils in late summer or early autumn once they’ve matured and the plants have begun to topple over.
How to plant Welsh onions
Welsh onions are typically started from seed, although you can also dig up a clump if you’re lucky enough to have a gardening friend with a patch. If you’re going the seed route, sow them as you would common onions, starting them indoors in late winter under grow lights or in a sunny window. Harden off the seedlings and transplant them to the garden several weeks before the last expected spring frost.
How to plant potato onions
Plant potato onions in the fall or spring from sets or bulbs from a garden centre, farmers market, or fellow gardener. In my region they’re available at garden centres in both spring and autumn, and fall planting typically results in larger clumps and larger bulbs. Plant each bulb 4 to 6 inches apart, covering the top of the bulb with 1 inch of soil. If planting in autumn, mulch the garden bed with 3 to 4 inches of straw to insulate the crop over winter.
How to plant chives
Chives can be grown from seeds started indoors in late winter, but it takes a few years for seed-grown plants to size up enough to start harvesting. Instead, it makes more sense to dig up a clump of chive plants from a gardening friend. Most gardeners have chives in their gardens and an established clump can easily be divided to share. Plant the division at the same depth it was growing in the previous garden and water well.
How to plant leeks
Leeks are generally grown from seeds started indoors in late winter. Sow the seeds in a lightweight potting mix under grow lights or in a sunny window, planting the seeds just a 1/4 inch deep. Harden off and transplant the seedlings into the garden 3-4 weeks before the last spring frost. You can also buy leek seedlings at a local nursery. Space plants 6 inches apart and rows 20 to 24 inches apart.
How to plant ramps
This crop requires some patience to establish. Ramps grown from seed take up to seven years to reach a harvestable size while those grown from bulbs are ready in two to three years. For the greatest chance of success plant ramps in their preferred location: beneath deciduous trees. The right way to add ramps to your garden is to grow them from seeds, source bulbs online, or replant plants from a local farmers market in spring. Don’t dig up large clumps of wild ramps and move them to your garden. Native stands should be respected so they continue to grow. If you find plants at a farmers market put them in your garden as soon as you get home, spacing them 6 inches apart and watering well.
How to grow perennial onions
As noted above, perennial onions are low-care plants, but there are a few tasks you can do to help maximize production. For all types of perennial onions stay on top of unwanted plants by pulling weeds as they sprout. I use my Cobrahead weeder, but you can also use a long-handled hoe. A mulch of straw can also reduce weeds as well as retain soil moisture. Most types of onions grow best in well-draining soil but they do need an occasional deep watering in summer if the weather has been hot and dry.
How to grow Egyptian onions
It won’t take long for your Egyptian onion bulbils to settle in and push out new growth. Help them along by pulling weeds, and watering deeply every few weeks if there has been no rain. Annual tasks include top-dressing with an inch of compost each spring and applying a complete organic vegetable fertilizer around the plants.
How to grow Welsh onions
It takes two to three years for Welsh onion plants to really size up and start to divide, but there’s not much for the gardener to do. Remove weeds, water deeply every few weeks if there has been no rain, and top-dress around the plants with an inch of compost in spring. The plants flower in mid-summer with the large white blooms attracting bees and other pollinators. Trim off the flower stalks as they fade, or leave them to go to seed and thicken up the clump.
How to grow potato onions
Potato onions are pretty much carefree in the garden. I top-dress with an inch of compost each autumn but generally let them do their thing. If I see that the bed is getting overcrowded and foliage production and bulb size begins to diminish, I’ll rejuvenate the patch. This is quick and easy. Dig up the clumps of bulbs, divide them, amend the soil, and replant. If you have unused garden space you may wish to move your plants to an entirely new bed. Rotating the crop every few years is beneficial for reducing potential pest and disease problems.
How to grow chives
Once established, chives need little care and maintenance. I apply an inch of compost to the soil around my chive plants in spring and cut the plants back to the ground after they bloom in early summer. This removes the woody flower stalks and promotes fresh leafy growth.
How to grow leeks
The most important task for leeks is to provide consistent water to encourage healthy growth. As the plants grow in summer, I also hill up soil around the stems or use a cardboard collar to block light and blanch the stalks. Blanching increases the edible portion of the plant. For a perennial bed of leeks, apply compost in spring and an application of an organic vegetable fertilizer.
How to grow ramps
Ramps take several years to establish and you can help give them a good start by removing weeds that pop up. Increase the moisture holding capacity of your soil by top-dressing the area with an inch of compost or chopped leaves each autumn. In times of drought, deep water the bed every few weeks.
How to harvest perennial onions
One of the biggest advantages of growing perennial onions is that you can enjoy multiple yields over a long period of time.
How to harvest Egyptian onions
There are several ways to enjoy Egyptian walking onions. Our main yield is the foliage, which emerges early in the spring. We cut off the hollow leaves as needed and use them like green onions. You can also cut the entire stem, not just the leaf. The underground portion of the stem can be peeled to reveal its tender white interior and we use them like scallions or leeks. We also pick the bulbils in late summer and autumn. They can be eaten as small onions (they are quite pungent) and are nice pickled.
How to harvest Welsh onions
You can dig Welsh onions anytime they’re big enough to harvest. I use a garden trowel to loosen and lift the onions. Yanking or pulling them from the ground can break the stems. If you dig up more than you intended just tuck the extras back in the soil.
How to harvest potato onions
It doesn’t take long for a bed of potato onions to establish into a nice sized clump. At that point, I pull up bulbs and greens as needed. You can thin selectively if you find some of the plants have become overcrowded. Or, you can dig up the entire crop with a garden fork in late summer when the tops yellow and fall over. Let the bulbs cure in a well-ventilated spot for a few weeks, trim the faded tops, and then place the bulbs in cool storage. Replant a portion of the crop in autumn for onions the following season.
How to harvest chives
Chive plants offer months of tender, grassy shoots to clip for meals. If you only need a little, use your fingers to pinch out individual stems. For larger harvests or enough chives to freeze or dry, cut bundles of the leaves using garden snips or garden shears. To learn more about gathering chives, be sure to check out this detailed article.
How to harvest leeks
To establish a perennial colony of leeks in your garden, start by planting twice as many leeks as you want to eat that first year. This gives you leeks to eat as well as leeks to perennialize. Dig the stalks, as needed in autumn and winter using a garden fork to lift the plants from the soil. Be sure to leave about half the crop. In spring, top-dress around the remaining plants with compost and fertilize with a slow-release organic vegetable fertilizer. By autumn (the second autumn for the plants), begin to harvest modestly by removing one or two side-shoots per plant. By the third year, the plants will have clumped up nicely and you can remove stalks as needed.
How to harvest ramps
Let your patch of ramps size up for a few years. When it’s time to start gathering plants, be selective and thin out larger clumps. Take no more than 10% of the patch at any one time. While the bulbs are edible, the leaves and stems offer the best eating. Carefully use a sharp knife to cut the leaves back to the ground. By leaving the bulbs in place you can ensure your ramp patch returns year after year.
For more information on growing onion family vegetables, be sure to check out these detailed articles:
- Why planting onion seeds is better than sets
- Curing onions for long-term storage
- How to harvest chives
- Choosing types of garlic to grow in your garden
- 15 easy-to-grow perennial vegetables
Do you grow any perennial onions in your garden?