Allium fistulosum

My first encounter with this particular Allium species was when I started my community garden in Serangoon North. One of my community gardeners brought it down from home and planted it in one of the planting beds there. She told us it was from China where she cut and used its foliage like spring onion leaves. Unlike the normal spring onion, its leaves are bluish green in colour and have a powdery bloom on them. They stand erect and continues to grow vigorously throughout the year in Singapore. It is vital to grow this plant in direct sunshine, otherwise, the leaves will tend to flop all over.

That was about three years ago and at that time, this Allium species was still not available in the market. It was only in the recent few months did I start to see pots of it appearing in our local nurseries. Most of the time, pots of the plants that are available for sale are not in bloom. There was only one occasion that I managed to purchase a pot that was in flower.

Botanically known as Allium fistulosum, this Allium species has various common names which range from Japanese bunching onion, Welsh onion, multiplier onion and scallion. It is widely grown in tropical Asia and does not develop bulbs like the common onion. It produces basal lateral buds which develop into many offshoots and hence the common name ‘bunching onion’. Flowers are produced in a spherical umbel on a hollow scape and they open from the tip of the umbel downwards.

Plants that appeared in the local nursery scene seem to be rather heat-tolerant since there are sources that report that Allium fistulosum does not thrive in lowland areas with temperatures greater that 25 deg C. This Allium species appear to be also able to tolerate the high rainfall encountered in Singapore as long as it is grown in well-draining, fertile soil that is also rich in organic matter.

I came across a source which mentioned that some Allium fistulosum cultivars flower in short daylength but in general, these conditions encourage vegetative than reproductive growth. Assuming all nursery stock on sale are at the same stage of growth, this could probably mean that there are several different (but indistinguishable) cultivars that are available for sale in Singapore, which explains why some batches of this Allium species do flower whereas others only produce leaves and never flower?