Sorry for the delayed post. We lost our internet in the storm 5 days ago. Just got it back. Ah rural life!
Planting Alliums in December
Sow backup bulb onions 12/5 in the hoophouse, see Alliums for November. These will be transplanted outdoors March 1st or as soon after that as feasible. If this sowing is not needed for transplants, they can be used as scallions. Regular bulb onions are a biennial crop grown as an annual (Allium cepa var. cepa)
Divide clumps of perennial leeks and replant (see Special Topic below)
Egyptian onions, aka Top-setting onions, tree onions, walking onions, produce tiny red-purple bulbs in the umbel instead of flowers, and were previously named Allium cepa var. proliferum. According to Wikipedia, they are now known to be a hybrid of A. cepa and A. fistulosum. Divide clumps in Spring (March, April) and fall (late September to November, depending on your climate)
Further south, warmer than zone 7, plant garlic and elephant garlic. Elephant garlic is botanically a leek (A. ampeloprasum var. ampeloprasum).
Potato onions and shallots (which develop in the ground) are Allium cepa var. aggregatum. Plant medium-sized (1½”-2″, 4-5 cm) potato onions in late November-early December in zone 7. See Alliums for September on planting the large ones. Save the small ones to plant in January, as they won’t survive the winter well in the ground. On the plus side, the small ones store really well indoors, unlike the large ones.
- For 360′ (110 m) @ 6″ (15cm) you need 720 bulbs plus 20% spare. Approximately 940 bulbs. 150 medium bulbs weigh about 20-21# (9 kg). 1# = 8 bulbs
- Plant them at 6″ (15cm). If there are not enough medium-sized onions available, increase spacing or fill out with small onions.
- Cover with ½-1″ (1-2 cm) soil, and add 4″-8″ (10-20 cm) mulch.
- Store any leftovers till January, when the small ones get planted, if you want more.
Here’s more information about Potato onions and shallots from Southern Exposure Seed Exchange:
“The potato onion is closely related to the shallot. Like the walking onion they aren’t largely referenced until the 1790s when they gain popularity in English and American gardens. Shallots on the other hand, have been recorded in use for centuries and date back to Roman times. Southern Exposure’s yellow potato onion variety is an heirloom that dates back to prior to 1790. Both the potato and walking onions saw widespread use in colonial America. They were often easy to grow in conditions that were less than ideal and easy to keep year after year. Sadly these perennial onions fell out of favor during the 20th century. People chose to grow more seed onions as onion seeds and sets became more widely available.
Benefits of potato onions and shallots
- They are not as readily bothered by the onion fly as are seed onions.
- Once you have enough potato onions or shallots you need not buy seeds or sets again.
- Some types of multiplier onions are in demand as gourmet items in restaurants.
- Potato onions and many shallots store well, and can withstand subfreezing temperatures in every area of the continental U.S. when properly planted.
- Perennial onions may be easier for you to grow. While some gardeners find seed onions to be an easy, productive crop others struggle with them. If you’re having a hard time with seed onions perennial onions are worth a shot.”
Harvesting alliums in December
Winter leeks, 12/8-3/1. Common leeks are Allium ampeloprasum var. porrum.
Hoophouse scallions, (spring onions, escallions or salad onions). Like bulb onions, these are A. cepa var. cepa. Early Lisbon and Evergreen Hardy White scallion varieties are hardy to 0°F (−18°C), as are chives, garlic, a few leeks (Alaska, Durabel), some bulb onions, and yellow potato onions.
Perennial leeks as leeks (see Special Topic below).
Leaves of Egyptian onions and perennial leeks: Cut and use these September to April, as long as they are still green and in good shape.
Other Allium tasks for December
Free trapped garlic shoots. Watch your mulched garlic beds and when the shoots start to emerge, choose the moment to free any trapped shoots, by working along the rows, investigating each spot where you expect a garlic plant to be, but see nothing. Your goal is simply to let the shoot see the daylight. Then it will right itself. Don’t reveal any bare soil, as that will grow weeds (and let colder winter air at the garlic.) Don’t over-work this – as soon as any part of a shoot is visible, leave that plant alone, and move on to the thousands of others. It isn’t necessary to make all the leaves visible, or to clear around the whole plant.
Choosing the right time might be tricky. I used to say when half or more of the shoots are visible, but one year we were having a crop disaster, and we waited too long – we were never going to have half visible. Usually, most of them emerge at the same time.
When properly planted and mulched, garlic can withstand winter lows of -30°F (-35°C). garlic roots will grow whenever the ground isn’t frozen, and the tops will grow whenever the temperature is above 40°F (4.5°C). If garlic gets frozen back to the ground, it can regrow and be fine.
Eat onions and garlic from storage, and if you harvested little bulbils from Egyptian onions in September, you can use them during the winter. They store well.
Special topic for December: Perennial Leeks (Allium ampeloprasum)
Divide clumps of perennial leeks and replant in late September to November and March-April. Harvest the larger leeks September to February, replant the rest. Ira Wallace of Southern Exposure Seed Exchange says:
“If divided and left to grow for 9-12 months, perennial leeks really make decent-sized leeks you harvest in October [or so]. This gives you something more like the early traditional leeks plus an assortment of smaller leeks to divide and let grow. [If you are] starting with only a few it’s best to just divide and grow larger for at least a year to get up to a decent quantity and size.”
In June, July and early August some people use larger bulbils in mixed pickles.
Perennial leeks will be dry bulbs in August and can be re-spaced between August and November into a larger planting for next year.