What are Egyptian Walking Onions
Egyptian walking Onions are the most common name for this very prolific and unusual Onion variety. Other names include Tree Onion because of their tendency to produce a branching stalk from a cluster of onion sets at the plants top giving them a tree-like appearance. Top-setting onions because they set onion clusters at the plant top as opposed to the common subterranean onions that other varieties produce. Winter Onions because of their Cold Hardiness. Perennial Onions because so long long as you leave the subterranean bulb / root undisturbed they will continue to come back and produce more top onions season after season.
The 'Egyptian' accolade was errantly assigned by seedsmen years ago, but these Onions probably didn't originate in Egypt and are believed to be a hybrid of common onions and welsh onions.
The onion bulblets sprout and grow from the original stalk, which at times will bend under the weight of the many tiny onions it produces. As it bends some of the top onions will touch the ground and take root producing new plants which gave rise to the name 'walking' onion.
Catawissa Onions, a type of Egyptian walking onion were bred in Catawissa, PA. for commercial growers and are a tad different form standard walking onions in that they produce more topsets from existing ones and have a quite bizarre appearance in that they look like plants growing from plants.
Catawissa Onions can attain a height in the ballpark of 5 feet, but generally average around 3 - 3.5 feet.
The topset Onions emerge in spring encased in a papery husk which eventually drops off of its own accord as the plant matures. They reach full maturity by late summer. They do at times produce some white flowers that are about 1/4 inch wide, but they are usually short lived and crowded out by the onions.
Growing Egyptian Walking Onions
Because they do not produce very many flowers - which is what produces the seeds - walking onion seeds can be hard to come by. They are generally propagated by onion sets.
Planting walking Onions from sets does not differ from planting standard onions. See - Onion Planting Guide
Unharvested topset onions that lie on the ground will self-sew and reproduce naturally. No re-planting is necessary once you have an established patch.
Egyptian walking Onions can be planted in either the Spring or Fall.
Walking Onions planted in the spring will produce a crop the same season by summers end, planted in the fall they will produce a crop in the following season. Some people also plant them in the summer, they will generally produce foliage in this scenario and the subterranean bulb and roots will develop but they rarely produce any top-set onions till the subsequent season.
If you plan on growing these as a perennial, season after season in the same location more careful attention needs to be paid to fertilization early in the season. The previous seasons crop[s] used many of the nutrients the plants require, fertilizer should be replenished.
Harvesting Top Set Onions
The best time to pick the topsets is once the stalk has browned a bit, in late summer. Most will have toppled over by this time, leaving a few on the ground will ensure additional plants come next season.
The greens are also edible are are cut and harvested at any time of year. Harvesting a few leaves from a healthy plant is feasible without detrimental effects on the plant as a whole. Be certain to harvest only the leaves - not the stalk that is producing the top-set onions.
Harvesting the subterranean onion bulb can be done in late summer and fall. This should only be harvested if you do not plan on having the plant regenerate next season.