|‘Shaker’ is one of the largest, most vigorous top-setting onions. Will Bonsall photo
By Will Bonsall
I want to have fresh onions all year, but there’s a window in late spring-early summer when any bulb onions left in the cellar are sprouted or rotten and the new crop has yet to come in. Moreover there are “spatial” windows – empty gaps in other crops or rows between other companion crops – where onions might fit nicely, but for a bit of shade from neighboring crops. While onions can manage without full sun, they don’t “bulb up” as well without that sunlight on their shoulders. That bulbing response is connected to their daylength sensitivity, or photoperiodism, and some varieties are more calendar-driven than others, so no amount of fertility or water or time will make them form larger bulbs.
Fortunately some types of onions are less dominated by the sun’s swiveling arc, mainly because they don’t try to make a bulb in the first place. They’re content to copy their leek cousins in merely forming a long slender shaft with little or no swelling at the bottom. Generically grouped as “multiplier onions,” they use a variety of strategies to propagate themselves, and those strategies offer a number of ways to integrate them into our garden space at almost every season. The only time they are unavailable is when the ground is covered with snow, and that’s when your bulb onions are conveniently tucked away in the cellar.
Common onions multiply by sending up a flower stalk in their second full year and making “true” or sexual seed. Paradoxically, that’s not what we mean by multiplier onions: The latter “multiply” by “dividing” at the base, whether or not they produce sexual seed. (Many but not all multiplier onions do that also.) However, in addition to multiplying by dividing (I don’t know how else to say that without subtracting from the meaning) and multiplying by making “true” seed, some multiplier onions multiply without dividing but by forming little clusters of tiny bulbs (“bulbils”) where a true flower should be. In effect they are little “sets,” and as such can be planted to propagate more scallions.
You may know multiplier onions by one of several names: Egyptian onions, top-set, nest or walking onions. All these types, whether propagated by seed or divisions or top-sets, make a bulbless green “bunching onion” or “scallion.” They never make a storable bulb.
Yet another refinement in onion reproduction is the “potato onion.” (Don’t be confused by the name; some folks plant them as a companion with their potatoes.) Potato onions are simply multiplier onions with divisions that do form a sizeable bulb – not as large as common onions perhaps, but large enough to store and use as onions. Moreover they usually form several of these onions in a clump, and the sum of those may equal or exceed the mass of a single large onion, the main drawback being that you have to peel more.
Some but not all of the seed-propagated bunching onions are Allium cepa, the same as common bulb onions; others are Allium fistulosa, often called Welsh onions. That’s a gross misnomer. My guess is that because of their growth habit they got associated with leeks, the national flower of Wales, but Welsh onions are about as Welsh as umeboshi plums. Yes, they are in fact Japanese in origin, and top-set onions are a cross between A. fistula and A. cepa.
Onions for All Seasons
My main point is that all of these forms of multiplier onions are highly useful in one way or another. Their diverse reproductive strategies make them harvestable at different seasons, some of them closing the gap between last year’s bulb harvest and the new crop.
If we direct-seed bunching onions in early spring, they’ll be ready to harvest in late summer or fall depending on how big we want them. Of course our common, or bulb, onions are ready then too, but bunching onions are especially suitable for stir-fries and salads, plus we can chop and freeze them to supplement bulb onions in the depths of winter.
Moreover they can fill a niche in the garden that bulb-onions cannot. For example, one of my favorite companion configurations in my intensive beds is a row of white runner beans down the center on poles. Toward the edge of the bed, 24′ away, is a row of Brussels sprouts, winter kohlrabi or perhaps late broccoli. As those brassicas size up, they’ll need every inch of that space, but for much of the season it seems like an unwonted waste of good ground. Bunching onions to the rescue: An inner row sown to them will suffer little or no competition from the brassicas until the scallions have made their critical early growth, after which they can continue to size up further in the partial shade.
If I needed to get a crop out of there even sooner, I could have direct-seeded the bunching onions elsewhere the previous fall and transplanted them in spring to the bed where they’ll have a head start on spring-seeded onions. Of course transplanting is more tedious that direct-seeding, but individual seedlings needn’t be transplanted; instead, little clumps of several seedlings can be grown per spot. A potential problem with dividing well-established scallions is that if they’ve made enough vegetative growth already, they’ll bolt to seed immediately and become useless for food (but fine if you want more seed for further direct-sowing).
One of my great garden needs is for something that does most of its growing in the very early spring and comes out before a neighboring crop (say, fava beans) creates too much shade or before a later crop (such as cukes or melons) spreads to hog all the space. For those situations my favorite is the Egyptian onion. There are many, but ‘Shaker’ is my favorite for vigor and size. Again, they’re grown from bulbils, which I can sow late the previous fall (after the equinox, for example) where another crop was recently removed or where a neighboring crop may still be maturing. There is some flexibility in how late I fall-sow the bulbils, but I prefer early enough so that they get well rooted yet late enough so that they barely get started before cold weather sends them into that suspended animation we Mainers call winter. That means they’ll be off and running as soon as the snow melts in April (which isn’t too early: the old-timers in my area used to say you could count on six weeks of sledding in March). Then they’ll have no inclination to send up flower stalks, which would immediately get tough and inedible. It also gets them out of the way long before a neighboring crop can shade or smother them. Early lettuce plants or radishes could serve a similar role, and I use them as well, but there’s a limit to how much of those I want for my own use (I’m not a market gardener), whereas I can freeze or dry any amount of scallions for later use.
Potato onions are a different matter entirely. Just as Egyptian onions are a cross between Allium cepa and A. fistulosum, I assume that potato onions were a later cross between Egyptians and large-bulb common onions. I’ve never read that; they told me so themselves. While the larger bulbs of potato onions make them a better substitute for common bulb onions, those larger bulbs also make them less suitable than scallions for close intercropping. Although I don’t have enough experience with potato onions to speak with certainty, they seem to demand full sun as much as the common bulb onions, and so are more difficult to companion. They might abide the shade of neighbors well enough, but make smaller bulbs, which is the whole point in growing them.
By the way, all of these alliums are rich in sulfur, which is essential for protein-building. However, I caution against heavy use of any of these onions, as well as garlic and leeks: According to the Vedic tradition of India, their use is said to impede spiritual attainments. I can positively attest to that from my own experience: I eat tons of those things all the time and I’m an atheist, so do be moderate.
A common pest in bulb onions is thrips and the viruses they transmit, but I have little or no problem with them in my bunching onions. I assume it’s because their foliage grows more when thrips are out of cycle, plus the scallions are usually harvested before their outer leaves senesce (age and weaken).
Because they’re a monocot (like grass), scallions like plenty of water and plenty of nitrogen. Since I usually companion them with other intensive vegetables, they have plenty of compost under them, and if the companion configuration allows it I also side-dress the young plants with dilute urine (for both water and nitrogen). Wood ash also helps, although it’s not as critical as it is for bulb onions.
In the case of the clonal (i.e. top-set) onions, I often need large amounts of the “sets” to fill in various areas at different times. For that purpose I keep a small nursery plot where I maintain several of my favorite top-set varieties (including ‘Shaker’) to serve as “mother plants.” That same plot also includes a few seed-forming varieties, both A. cepa and A. fistulosum. Because they are both cross-pollinating species, their sexual seed will not be pure. Not that I care about that – any combination of them serves my purpose if they’re for eating. Periodically, however, I’ll take some divisions of each variety and move them into one of my several isolated seed plots where I can propagate fresh sexual seed that is true-to-type for that variety. Considering how important these are in my garden and on my plate, I don’t want to run out of them.
About the author: Will Bonsall lives in Industry, Maine, where he directs Scatterseed Project, a seed-saving enterprise. His book on gardening and homesteading will be published by Chelsea Green this summer. You can contact Will at [email protected].