During 2016 I purchased my first Tree Onions, Top Onions, Topset Onions, Top Setting Onions, Walking Onions, Egyptian Walking Onions, Air Onions. and each year after I was on top of growing the Catawissa onions I had invested in and had 100's of them growing in the space saver greenhouse at home, some got replanted and others were for consumption.
In 2022 I purchased five bulbils of Moritz Egyptian, Catawissa' 'Catawissa Onion', McCullar's White Topset Onion and Amish Walking Onions for my new allotment plot because I knew from experience, just how fast these little beauties grow and how many bulbils you end up getting from each plant.
Due to getting diagnosed with cancer and having radiotherapy and then dealing with recovery and arthritis in all my joints following the treatment the allotment got away from me late 2023 and during 2024, and in Autumn I'm now altering the infrastructure of the plot and taking areas back that have been overrun with bindweed.
My plan is to dedicate one of the new raised beds to Walking Onions and I have just purchased another five of the following bulbs because I don't know what's under the bindweed yet and how many onions I may recover when pulling the bindweed up from the existing Walking Onion bed.
A = Moritz Egyptian
Similar to the typical tree onion, but the bulbs are a deeper colour (red-purple) and the topsets are slightly larger than most strains. An unusual strain that will sometimes produce sets in the middle of the stalk.
B = Catawissa' 'Catawissa Onion'
A very hardy cultivar of Canadian origin, distinguished by its vigorous growth and the rapidity with which the bulbils that commence to grow without being detached from the top of the stem. The bulbils divide into tiers, the second set of bulbils producing green shoots, leaves or barren stems to bring the height of the plant to over 75cm.
C = McCullar's White Topset
This form produces a number of white bulbs below the ground about 2.5cm or more in diameter, plus pea-sized bulbils at the top of the flower stalk. The larger bulbs are used for eating; the bulbils are used for replanting. It is used primarily as a source of greens when other onions are dormant.
D = Amish walking onions
Similar to the Catawissa tree onion, but the bulbs are smaller in size and darker red/purple colour and the topsets are smaller than most strains.
Botanical Name: Allium cepa proliferum
Common Names: Tree Onions, Top Onions, Topset Onions, Top Setting Onions, Walking Onions, Egyptian Walking Onions, Air Onions
Description:
The tree onion is a biennial plant meaning it should usually flower in its second year. However, you will find it produces small onion bulbs at the base of the plants and a multitude of small top sets where a flower should be. The number and size of bulbils can vary significantly between about 3 large top set onions and 15 smaller sets.
The parent onion behaves as a multiplier or shallot and can split to produce several small tender onions that can be eaten or regrown.
Edible Uses:
The top sets or bulbils are an ideal size for pickling or chopping into salads. The onion greens can be used just like spring onions The mature onions are tender and can be used raw or cooked like normal onions.
Planting in the UK:
Planting Period: May to December. The tree onion is quite hardy but can certainly benefit from a top mulch or growing in an unheated greenhouse to protect from frosts until it becomes established
Depth: Plant about 25mm (1 inch) deep
Spacing: Allow about 15 to 20cm between plants (6 to 8 inches)
Soil – Growing Medium: If growing in the ground, try and prepare the area in advance to produce a rich, free draining loam with a slow release, low nitrogen fertiliser. Tree onions can be grown in most composts but ensure they don't remain waterlogged or rotting of the bulb can occur. Pot grown plants can benefit from a full spectrum fertiliser that contains calcium, magnesium and sulphur.
Harvesting:
Onions have a natural cycle and the onion stems will tend to dry and die back as the goodness is transferred to the onion bulb. Collect the bulbils and replant those you are using for propagation. Collect the base bulbs and allow to air dry, preferably on a mesh to avoid damp areas that may encourage mould growth. Store in a cool, dry area.