Allium × proliferum
Tree onion
Common names: Egyptian walking onion, Top onion
At a glance
- Light
- Full sun
- Spacing
- 20 cm, rows 30 cm
- Lifespan
- Perennial
- Harvest
- May–Oct
- Hardiness
- Hardy down to −18 °C
- Water need
- Medium
Photo: Kurt Stüber [1] · CC BY-SA 3.0 · Source
Description
The tree onion is a hardy perennial that produces small bulbils in airy tiers above the stem instead of flowers, hence its name. These bulbils can be harvested or replanted, so no seed sowing is required. It provides flavorful onion greens almost year‑round and is extremely winter hardy.
Care instructions
Plant the airy bulbils in late summer or autumn in a sunny spot; they will root over winter. Leave some stems with bulbils standing so they will self‑multiply. Harvest the tubular leaves continuously from May onward and split overcrowded clumps every few years in spring.
The care notes were machine-translated from German.
Garden year
HarvestMay–Oct
Soil & site
Soil pH
Soil type
humus-rich, well-drained, loamy, lime-loving
Give the tree onion loose, humus-rich and free-draining garden soil, as for ordinary kitchen onions. You must avoid waterlogging at all costs; it makes the bulbils rot and is the most common reason for losses. A neutral to slightly calcareous soil (pH about 6.0 to 7.5) suits it well; on heavy loam, work in sand or mature compost beforehand so that the water drains better.
Allium family (onion, garlic, leek), moderate feeder. A 4-year break prevents onion rot and leek moth. They make good neighbours for carrots.
Feeding
Light feeder
Months
Mar–Apr
In early spring at new growth, work a little mature compost in shallowly around the plants; this is enough for the tree onion, a light feeder, for the whole season. On very poor soils you can also scatter in a handful of horn shavings, which release their nitrogen slowly. Feed rather sparingly: too much nitrogen drives leaf growth and comes at the expense of bulbil formation.
Overwintering
The tree onion is fully hardy and stays in the bed: no lifting, no protection needed; in mild winters the foliage stays green and you can keep harvesting. In a pot, place it out of the wind and wrap it in a coconut or hessian mat so that the root ball does not freeze through.
Propagation
Methods
- Offsets
- Division
The easiest way to propagate the tree onion is by its characteristic bulbils, which form at the top of the stem instead of flowers from June to September. Harvest the bulbils from August onwards in late summer, when they are strong and ripe, as they then come away easily from the stem. Push them in straight away or in early autumn about 5 cm deep into well-loosened soil; alternatively, lay them on the surface and only press them down lightly. Keep about 30 cm between plants in the row. If you leave the stems standing, they bend to the ground under the weight by themselves and the bulbils root on their own, which is how the plant naturally walks on. The second method is division of the bottom bulb: dig up the mother clump in autumn and carefully separate the side bulbs that have formed. Replant them at once with enough space (at least 20 to 30 cm). A single plant can in this way deliver several hundred sets within a few years through both methods together. Skip sowing, as Allium proliferum is a sterile hybrid and does not form viable seed.
Companion planting
Good neighbors
carrot family (Apiaceae)
Umbellifers and alliums confuse each other's pests (carrot fly, onion fly).
For example CeleriacDillParsleyFlorence fennelCorianderCelery (Stalk Celery) and 20 more species in the catalogue
Source: classic companion planting (DACH-Gartenpraxis)
rose family (Rosaceae)
You can plant garlic and chives under strawberries and roses; their scent repels aphids and other pests.
For example AppleRaspberryClimbing rosePearAroniaAlpine strawberry and 58 more species in the catalogue
Source: Bio-Gärtnerei Mixed Culture Practice
Rather not
legume family (Fabaceae)
particularly well establishedAllium species inhibit the nitrogen‑fixing rhizobia of legumes through their root exudates, which slows their growth.
For example Pole beanBroad beanSnow peaWrinkled peaRunner beanLima bean and 34 more species in the catalogue
Source: basic crop‑rotation rule
Companion planting is partly traditional gardening lore. Where the reason is known, it is given.
Some of these explanations were machine-translated.
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