Egyptian Walking Onion

Allium proliferum are extremely easy to grow.  Egyptian Walking Onions are extremely hardy plants. They have endured harsh winters with temperatures plummeting down to -24° below zero! Hence the name, "Winter Onion." They grow well in zones 3-9.
One of the first plants to emerge in spring the leaves of Egyptian Walking Onions poke through the soil and will grow up to 3 feet in height.  The leaves are round and hollow.  At the top of the plant, a cluster of "bulblets" will begin to grow, known as "bulbils" or "sets", every plant will produce a cluster.  Early spring will show its "bulbils" encased in a papery covering.  As they grow, this covering will tear open and fall off.  In late summer the "bulbils" will reach maturity. At this stage the "bulbils" look like mini versions of their parent.  When the "bulbils" become too heavy they will pull the plant over and the fallen bulbils will take root and grow into new plants.
This process is repeated over and over and is how the plant got its name "Walking Onion".  They literally walk across the garden!
Occasionally this onion will produce miniature flowers among its bulbils.  These flowers are about 1/4"wide, have 6 white petals and 6 stamens. Each petal has a vertical pea-green stripe.  Most flowers dry up as the bulbils compete for energy making it rare to find a viable seed.
Clusters of bulbils can have as few as 2 , or as many as 30 onions.  On occasion a new leaf stalk will grow from a cluster of bulbils, looking like a branch, producing another cluster.  This is where the name "Tree Onion" comes from.

Once the bulbils root and start to grow in the ground they produce shallot-like onions which can be harvested.  These will not grow back.  If these are left in the ground the above process will repeat itself year after year.

Egyptian Walking Onion

During their first year they will not produce "bulbils". You might see only greens. 

During their second year they will produce "bulbils".

You can snip off a few early chive-like leaves, leaving the rest to grow on into spring onions. Pinch some off to enjoy in April and May – the rest will grow taller and begin to develop bulbils on the end of the leaves.
Once established, plants may be propagated by division or by planting the sets that grow from the top.

Planting in the spring: Sets will grow throughout the spring and summer and develop tall green leaves and bulb/root growth in the ground. Since it is the plant's first growing season, it will probably not produce "bulbils".

Planting in the summer: Sets planted at this time will grow roots and leafstalks, and have some onion bulb development in the ground, but they will not produce "bulbils".

Planting in the fall: This is the optimum time to plant sets. Sets planted at this time will grow roots and leafstalks only. The leafstalk will die back for the winter.  The set will develop into a small onion bulb in the ground and store enough energy to carry itself through the winter. A leafstalk will reemerge in the spring and the plant will grow throughout the spring and summer to maturity.

Planting in the winter: You can plant sets in the winter as long as the soil is not frozen. If you can dig a 2" deep hole in the soil, then you can plant your sets. The sets will not grow much at all - maybe a little bit of root growth only. 

Harvesting the 'Bulbils': In mid to late summer and autumn the top-sets may be harvested. The optimal time to pluck off the bulbils is when the leafstalk has dried and turned brown. More than likely, it has fallen over by this time. Be sure to remove any bulbils that have fallen to the ground if you do not want them to self-sow in their new locations. Despite their name, these plants are very easy to control and keep from spreading just by harvesting the top-sets. You can eat, plant, or store the bulbils.

Harvesting the greens: The greens (leaves) may be cut and harvested at any time of the year. Just harvest one or two leaves from each plant. Be careful not to cut the stalk that has the bulbils. Soon after you have harvested the leaves from the plant, new leaves will start to grow in their place which can be harvested again.

Harvesting the onion bulbs in the ground: The onions at the base of the plant that are growing in the ground can be harvested in late summer and fall. Be sure to leave some onions in the ground for next year's crop. The bulb is about the same size and shape as a shallot. Bigger bulbs may be obtained by cutting off the bulbils before they develop. That way the plant can put its energy into the onion bulb in the ground instead of into the bulbils. 

Note: if you harvest the onion bulb in the ground, you will destroy the plant - it will not grow back next year. So, if you want to eat the onion bulbs in the ground, make sure to replace them by planting topsets, or offsets from the bulb.

Eating your Walking Onions

The onions taste just like a regular onion, only with a bit more pizzazz! The entire plant can be eaten. Small onions form at the base in the soil. They can be eaten and prepared just like any other onion. The hollow greens may be chopped to eat like chives or green onions. They are excellent when fried, cooked in soups, or raw in salads (my favorite). The bulblets that grow from the top are excellent when peeled and fried or you can pickle them, or pop them in your mouth, they're a little spicy!