American onion (Allium unifolium)
American onion (Allium unifolium) is a bulbous (or similar) plant that can grow 10cm – 50cm tall and up to 10cm wide. In this growing guide we’ll learn the cultivation details and how to plant American onion (Allium unifolium).
This plant is commonly known as American onion.
This is a deciduous plant that takes 2-5 years to reach full maturity.
In this article
Plant profile
Common name: American onion
Scientific name: Allium unifolium
Plant type: Bulbs
Habit: Columnar / Upright
Height: 10cm – 50cm
Spread: Up to 10cm
Foliage: Deciduous
Sunlight: Full Sun
Soil: Chalk, Clay, Loam, Sand
Moisture: Moist but well drained, Well drained
Garden type: Rock & Gravel Garden
Planting type: Flower borders and bedding
Other characteristics: Plants for pollinators, RHS Award of Garden Merit
Seasonal colors
| Season | Stem | Foliage | Flower | Fruit |
|---|---|---|---|---|
| Spring | ||||
| Summer | ||||
| Autumn | ||||
| Winter |
How to plant American onion (Allium unifolium) – Stickpen, Public domain, via Wikimedia Commons
Bulbous plants are found all over the world in habitats as diverse as woods, meadows, riverbanks, rocky hills and mountains.
There are bulbs suitable for all types of garden design.
Most have their own limited flowering season, but with careful planning it is possible to combine this period of interest with the other plants in the garden.
Other types of Allium to consider:
See all Allium
How to plant
In this section we will learn how to plant American onion (Allium unifolium), know its needs in terms of soil, watering and sun exposure.
Soil
American onion (Allium unifolium) is a plant that adapts to all types of soils, chalk, clay, loam or sand.
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The chalky soil is pale and contains chunks of calcium-rich rock. It is a fertile and well-draining soil, almost always alkaline.
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Clay soil is composed of more than 25 percent clay particles. These particles have a high moisture holding capacity and the soil is heavy to dig and can be waterlogged in winter (dry in summer).
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The loam soil is dark, rich in organic matter but balanced in minerals. It offers the best of all worlds, retaining enough water for the plants, but allowing excess moisture to drain away. This is the most desired type of garden soil, perfect for most plants.
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Sandy soil is light, porous and very easy to drain. It is a soil poor in organic matter and nutrients. It is composed of relatively large mineral particles that allow water to drain quickly.
It is not very sensitive to soil acidity or alkalinity and grows well in soils with pH acid, alkaline or neutral.
Regarding drainage, Allium unifolium likes to grow in moist but well drained or well drained soils.
Sunlight
American onion (Allium unifolium) should be grown in full sun places.
Cultivation profiles – Growing American onion (Allium unifolium) – Michal Maňas, CC BY 2.5, via Wikimedia Commons
