Harvesting Alliums (onions, garlic and relatives)

Onions curing and drying in strings.
Credit Southern Exposure Seed Exchange

The allium family includes all kinds of onions, garlic, leeks, perennial onions such as potato onions, and also less well known alliums, mostly perennials.

This is the time of year for harvesting most alliums except leeks. (It’s the time for planting out leeks for fall and winter harvests.)

I have a whole series of Alliums for the month posts. Here’s a link to Alliums for June. It includes the starter for the list I provide here, of the relative timing of harvests for various alliums.

Order of Allium Harvests

Our allium harvests generally occur on these dates. Your dates will differ but you can expect this order of harvests:

  1. Nov 18–May 10: Onion scallions in the hoophouse
  2. Mar 15–May 31: Garlic scallions
  3. May 7–May 28: Garlic scapes
  4. May 10–Jun 30: Onion scallions outdoors
  5. May 25–Jun 10: Green bulb onions (Allium cepa)
  6. May 30–Jun 8: Hardneck garlic
  7. May 30–Jun 11: Potato onions ( cepa aggregatum) planted in fall
  8. Jun 6–Jun 25: Potato onions planted in January and February
  9. Jun 10: Shallot bulbs (cepa aggregatum), fall-planted. They are not fully hardy in zone 7a. I recommend storing bulbs and replanting in early spring instead
  10. Jun 11–Jun 12: Softneck garlic bulbs
  11. Jun 11–Jul 11: Bulb onions sown in fall, with slow spring-sown ones to Jul 26
  12. Jun 19–Jul 2: Cipollini (cepa cepa) Small bulb onions grown in a hoophouse from spring transplants
  13. Jun 30–Jul 5: Elephant garlic ( ampeloprasum ampeloprasum) We stopped growing this when too many winter-killed
  14. Jul 1–Jul 8: Shallots from bulbs refrigerated over the winter and replanted in early spring
  15. Jul 1–Jul 15: Cipollini outdoors from spring transplants
  16. July: L’itoi (A. cepa aggregatum). This peppery little perennial clumping onion sends up edible shoots in early July.
  17. Jul 4–Jul 30: Shallots from seed started in late January, plugs transplanted in March. Harvest 4–8 weeks later than those from bulbs replanted in October
  18. July–September: The small red-purple bulbils of Egyptian onions can be pickled. Earlier in the year, before the bulbils appear, harvest the tasty, succulent leaves of this very hardy perennial.
  19. Spring, summer, fall according to size: Welsh onions ( A. fistulosum) are non-bulbing, hardy perennial onion greens, larger than chives and scallions. Japanese bunching onions are similar. Can be sown in fall or spring. Clumps can be divided and replanted
  20. Sep 6: Shallots direct sown outdoors in February and March

Here’s some details on harvesting some of the smaller alliums

Harvesting onion scallions

Scallions ready-to-harvest.
Photo Pam Dawling

From around May 10, through June, our outdoor onion scallions are big enough to harvest (just as the hoophouse ones finish up!) We start these from seed in January and February and transplant as clumps in March and April. In cooler climates, you can schedule harvests through summer, but we cannot get good quality ones here after late June. It’s good to develop an efficient harvest method with little scallions or it takes way too long. To harvest, loosen the soil with a digging fork, then lift out a clump. Deal with scallions in bunches as much as possible, rather than one at a time. Shake the plants, and trim off the roots and the ragged tips. Holding the bunch in one hand, pass the scallions one at a time to the other hand, separating them and pulling off a single outer leaf, not more. Don’t fuss with them too much. Next set the scallions in water in a small bucket, to clean themselves while you work on the rest. If you are going to band them, start out with a bunch of rubber bands around three fingers on the hand that holds the bunches (leaving the forefinger free for tasks demanding dexterity). When you’re ready to band them, use the other hand to pull a rubber band into position. When the bucket is full enough, dunk the scallions up and down, and transfer them to a clean bucket with a small amount of water to keep them fresh.

Harvesting garlic scallions

A healthy patch of garlic scallions in spring
Photo credit Kathryn Simmons

Garlic scallions (small whole garlic plants) provide our first allium harvest of the calendar year, starting in mid-late March and continuing (if we have planted enough) into May. Some people cut the greens at 10″ (25 cm) tall and bunch them, allowing cuts to be made every two or three weeks. We prefer to simply lift the whole plant once it reaches about 7″–8″ (18–20 cm) tall. You may need to loosen the plants rather than just pulling. The leaves keep in better condition if still attached to the clove. Trim the roots, rinse, bundle, set in a small bucket with a little water, and you’re done! Garlic scallions can be sold in bunches of three to six depending on size.

Harvesting garlic scapes

Harvesting garlic scapes
Photo by Wren Vile

Another spring allium harvest is garlic scapes (the firm, edible flower stems of hardneck garlic).  Here scapes appear when tulip poplars flower. In a warm spring, that can be the end of April. Garlic scape arrival is partly temperature dependent. We harvest scapes two or three times a week for about three weeks, until there are no more. At the Roxbury Agriculture Institute at Philia Farm in New York State, they wait until the scape has curled round, then cut it off. We harvest ours sooner than that, in order to let the bulb grow as big as possible. We pull our garlic scapes to get the most out ! In our climate, the appearance of scapes indicates the garlic will be ready to harvest in three weeks. I’m not sure if the same timing works everywhere, so keep records and you’ll learn what to expect. Exactly how day-length and temperature interact as triggers for scape and bulb harvest dates, I don’t know. I’ve done some research, but haven’t found much solid info yet.  In general, plant flowering is triggered by some combination of enough vernalization (chilling hours — maybe 10 weeks below 40°F/4.5°C), plant maturity, temperature and photo-period (the relative length of day and night). In cold weather the plants suppress the flowering signal. The leaves perceive the amount of daylight, and when the temperature is also right, they trigger flowering by sending a signal (called Florigen) to the shoot tips. Florigen may be an actual compound, or may be some combination or ratio of several hormones produced by the plant. Almost all these factors are outside our control once the plant is in the ground, so the best we can do is pay attention and be ready to act.

Harvest garlic bulbs and bulbing onions

(see Alliums for June) I won’t go into details here, as I’ve done that previously.

240 heads of garlic drying in Tenax fencing.
Photo Sierran Farmer

Harvest small potato onions

produced by large ones planted in September.

Yellow Potato Onions.
Photo Southern Exposure Seed Exchange

Harvesting cipollini

(aka cocktail onions, boiling onions, pickling onions)

Red Marble cipollini.
Photo Fedco Seeds

These small, attractive onion bulbs can be easier to grow in marginal onion climates than full-sized onions or can be an additional allium crop. The larger ones can be used as fresh bunching onions. All may be cured. Cipollini naturally have more sugar than most onions, which makes them ideal for caramelizing or roasting whole. The scheduling and final size of your cipollini will depend on your latitude and temperatures.

Alliums for May: harvesting garlic scapes, scallions and fall-planted potato onions

Pickled garlic scapes, okra and beets.
Photo Bridget Aleshire

This is the first of a new monthly series of blog-posts on Alliums for the Month, which, like my previous series on lettuce and Asian greens, I plan to run for a year. Alliums are the onion family. With this series, I’m going to talk about which alliums to harvest each month, which to plant, and which need other kinds of attention.

Weeding alliums

I haven’t thought of any alliums to plant in May (at least, not here in central Virginia), but there’s plenty to harvest, and don’t forget to weed! Because alliums don’t have big spreading leaves, they are not good at shading out weeds, so we have to take care of the weeds for them! Particularly bulb onions and garlic this month, as they are only a few weeks away from harvest and will benefit from removing weeds and mulch to let in fresh air to help the bulbs dry down (rather than get fungal diseases!)

Harvesting garlic scapes

Starting any day now, we will begin harvesting garlic scapes (the firm, edible flower stems of hardneck garlic). My previous posts about scapes are some of my most popular ones.

Pulling garlic scapes.
Photo Wren Vile

See last year’s Garlic scapes, upcoming events, hoophouse seed crops, posted on May 2, 2017. There I noted that in 2017, scapes came early, as did Tulip Poplar flowers, at the end of April. We harvest scapes two or three times a week for about three weeks, until no more appear. Garlic scapes are one of the first outdoor crops of the year, apart from rhubarb and asparagus, and their flavor is refreshingly different from leafy greens (the staple hoophouse crops of early spring) and stored winter roots.

I posted Garlic scapes! Three weeks to bulb harvest on May 11, 2015. That year scapes were later than average. This post is a very popular one, and I’m still wondering if I was over-confident in predicting 3 weeks to bulb harvest everywhere in the US! Please do leave a comment if you have records for how long you get between scapes and garlic bulb harvest.

I’ve done some research into what triggers flowering in garlic, but haven’t found much solid info yet.  In general, plant flowering is triggered by some combination of enough vernalization (chilling hours during the winter and early spring – maybe 10 weeks below 40F), plant maturity, temperature and photo-period (the relative length of day and night). In cold weather the plants suppress the flowering signal. The leaves perceive the amount of daylight, and when the temperature is also right, they trigger flowering by sending a signal (called Florigen) to the shoot tips. Florigen may be an actual compound, or may be some combination or ratio of several plant hormones, produced by one or more genes in the plant. Almost all these factors are outside our control, once the plant is in the ground, so the best we can do is pay attention and be ready to act.

There is a bit more information about the triggers for bulb initiation and for drying down. Garlic bulb initiation (and the end of leaf growth) is triggered by daylight increasing above13 hours in length (April 10 here at 38°N). Soil temperatures over 60°F (15.5°C) and air temperatures above 68°F (20°C) are secondary triggers. When I was in Jamaica last May, I researched growing garlic in the tropics, and it may be that temperature is a bigger trigger and daylength is less important in tropical latitudes where daylength does not vary much. Certainly some growers had produced garlic when I didn’t expect it to be possible.

Hot weather above 91°F (33°C) ends bulb growth and starts the drying down process. I don’t yet know how many hours over that temperature the garlic needs before drying down is triggered. We had a few very hot days last week.

It is important to get plenty of good rapid growth before conditions prevent any more growth. Garlic can double in size in its last month of growth, and removing the scapes (the hard central stem) of hardneck garlic can increase the bulb size 25%.

In the 2015 post I described how we pull our garlic scapes, to get the most out–we love this crop! We also appreciate a late-morning task that’s done standing up! In that post I described the value of mulch and when to remove it.

Garlic scapes to cheer us up posted on May 10, 2013 has been reread a lot–whether that’s because readers love garlic scapes, or seek cheering up, I can’t say.

Pulling garlic scapes – the long view.
Photo Wren Vile

Our harvest process

Here’s the short version. Those looking for more detail can go to my 2015 post.

  1. When scapes arrive, plan some late morning or early afternoon time two or three times a week to harvest them.
  2. As soon as the pointed cap of the scape has emerged above the plant center, firmly grasp the stem just below the cap and pull slowly and steadily straight up. The scape pops as it leaves the plant and you have the whole length of the scape, including the tender lower part.
  3. Gather them into buckets, with the scapes upright, so they are easy to bunch or cut up.
  4. Put a little water in the bucket.
  5. They store well in a refrigerator for months if you don’t use them sooner.
  6. In a few days, more scapes will have grown tall enough to pull, and you can have a second chance on any that broke at your earlier attempt.

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Clumps of scallion transplants in a Speedling flat, ready to transplant earlier in spring.
Photo Pam Dawling

Harvesting scallions

In May our outdoor planted scallions start. For outdoors, we use transplants, started in January and February, and transplanted in March and April. We sow in Speedling plug flats, a small pinch of seed in each cell, and transplant the undivided clump/plug. We can get a lot of scallions in a small space. Around May 10, the first ones are big enough to harvest (just as the hoophouse ones finish up – what planning!)

To harvest, we loosen the soil with a digging fork, then lift out a clump. We shake the plants, keeping them in a cluster, and trim off the roots and the ragged tops. Holding the bunch in one hand, we pass the scallions one at a time to the other hand, pulling off a single outer leaf and giving the base of the plant a wipe with our spare hand. Next we set the scallions in a small bucket in water. When the bucket is full enough, we dunk the scallions up and down, and transfer them to a clean bucket with a small amount of water to keep them fresh.

Scallions planted in bunches, ready-to-harvest.
Photo Pam Dawling

It’s good to develop an efficient method with little scallions or the harvest takes way too long. Deal with scallions in bunches as much as possible (digging up, trimming), rather than one at a time. Pass them from hand to hand when cleaning rather than set them down on the ground and pick them up again one at a time. Set them into water so they are cleaning themselves while you work on the rest. Don’t fuss with them too much – pull off a single outer leaf, not more. Don’t pick at little bits of skin, unless quite gross. If you are going to band them, start out with a bunch of rubber bands around three fingers on the hand that holds the bunches (leaving the forefinger free for tasks demanding dexterity). When you’re ready to band them, use the other hand to pull a rubber band into position.

Roxbury Farm in New York State has a wonderful Harvest Manual. Page 45 on scallions says they harvest 50 bunches an hour, including trimming tops as needed, but not roots. They wash 100 bunches an hour on a bench, in bunches, with a power spray.

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A potato onion plant in early spring, showing the cluster that has developed.
Photo Kathryn Simmons

Harvesting fall-planted potato onions

Potato onions (Allium cepa var. aggregatum) are a type of hardy, perennial multiplier onion–once you have them you are self-sufficient. You don’t need to buy seed each year, but select the best bulbs from the ones you grew to replant for the next crop. Also known as Hill Onions, Mother Onions and Pregnant Onions, they produce a cluster of tasty (but not too pungent) bulbs from a single planted bulb, or a large bulb from a small one.

Potato onions have good drought resistance, pink root resistance, onion fly resistance and are widely adapted for different growing regions (not Florida or southern Texas). When properly planted they can withstand sub-freezing temperatures in every area of the continental U.S.

You can order potato onions from Southern Exposure Seed Exchange and other suppliers to be shipped in the fall. See SESE’s Perennial Onion Growing Guide and Garlic and Perennial Onion Growing Guide for growing information.

Yellow potato onions.
Photo Southern Exposure Seed Exchange

The potato onions which were planted earliest (September for us) will be ready to harvest first, at the end of May or early in June in our central Virginia climate. Once you see the tops start to fall over, stop watering the onions and let them dry down.

Potato onions are ready to harvest when the tops die. Not all will be ready the same day. Because onions easily get sunscald if left exposed after they are mature, it’s best to harvest the mature ones every few days. Don’t break over the tops in hopes of a single harvest–it really reduces the storage life. The potato onions sit on the surface and are easily picked up without tools. Handle them gently, to prevent bruising and scratching. Put them into crates or buckets, without pulling off any leaves.

The September planted potato onions were the largest bulbs when planted, and they will usually have divided and produced clusters of small onions. Do not break up the clusters as you harvest, because this triggers sprouting. Set the clusters in a barn or shed, on an airy bench or horizontal rack. The tops break easily, so you cannot hang them as you might hang garlic. Potato onions need good ventilation: we use box fans continuously.

If you find any bulbs larger than 2.5″ (about 6 cm), go ahead and eat those. The giants do not store well. Alternatively, refrigerate them till September and replant. The small and medium-sized bulbs keep 8-12 months under good conditions, and are the best to replant to grow more onions.

Potato onions need sorting about once a month to remove any that are rotting. We plant our large ones in September or early October, our medium-sized ones in late November and our small ones in late January. I’ll tell you more about those when the time comes.

Two beds of potato onions in spring, of different planting dates.
Photo Kathryn Simmons