What is Tree Onion?
Tree onion (Allium x proliferum) also known as Walking Onions, Egyptian Onions, Topset Onions are a perennial onion. They are part of the Alliaceae or onion family and is a hybrid of the common onion (Allium cepa) and the welsh onion (Allium fistulosum). Tree onions are the easiest of the onions to grow coping with 40-degree heat and frosts. When a single bulb is planted over the weeks it will produce up to 10 more bulbs around it before sending up a strong stem. At the end of the stem instead of flowers will grow 6 to 8 bulbils, or small baby onions. These bulbils will then start to shoot and as the top begins to get top heavy will fold over until the top is touching the ground and the bulbils will take root. The cycle begins again. This is why they are called walking onion as if let to grow the plant will literally walk across the garden.
When harvesting it usually takes around 5 months before the bulbs can be dig up or when the stalk drys out. The bulbils can be picked in late Summer before they start to sprout. If they have already sprouted, you can plant them in the ground immediately for them to grow on. Save some bulbs for replanting or just replant the bulbils and eat the bulbs. Once lifted dry the same way as regular onions. Spread the bulbs on a wire screen in a cool, well-ventilated shelter to dry. Store in a cool, dry place or hang up in open weave bags.
Benefits of Growing Tree Onion
Tree onions are easy to grow and the whole plant is edible. The top bulbils can be eaten cooked or raw and are good for pickling or sliced in salads. The stalk of the onion can be used like a spring onion. The base bulb is a tender and juicy. Tree onions will keep for up to 12 months. During harvesting you should have new bulbils to plant for the next season crop.
How to Grow Tree Onion
Cool to sub-tropical.
Height: 60cm, Width: 5-10cm
When To Plant Tree Onion
Plant in Autumn to Winter.
A rich loam soil is required for a good crop. Enrich soil with low nitrogen fertilisers and lime a few months before planting time. Do not use manure as this will lower the pH of the soil.
How To Plant Tree Onion
Plant in full sun, 40cm apart with the bulb planted with just the top poking out of the soil or the bulbils planted just under the surface of the soil.
Tree Onion Plant Care
Normal watering is required during dry periods.