The Edible Allium
Common Name: Onion
Scientific Name: Allium cepa
Onions, are the most used vegetable in many Kitchens. It ranks above Potatoes and even Tomatoes. So why don’t we grow more of them? A few simple grow rules to remember and this edible allium once planted out Onion seedlings do not need much attention, apart from watering and every gardener’s favourite job, weeding.
Rekha’s Garden Tips
Seeds or Sets
- Start onion sets (immature bulbs) early Springtime in 3cm individual pots or module trays. Use good quality growing media with added grit for drainage.
- In February sow seeds either in 3’s (for single bulb) or in 5’s ( for 3 bulbs), in module trays, with sufficient heat given from below, to germinate the seeds. As soon as seedlings emerge, remove from base heat and allow to continue growing in an unheated greenhouse with a propagator lid placed over the top during the nights. Later removing the weaker seedlings.
For either, bulbs/seedlings should be moved into a cold frame, around 6 weeks after first seedling shoots appear, this ensures a good hardening off period, prior to planting out.
Prep Growing Area
Whether using a dig or a no dig method, both require prepping ahead of planting out in early to mid Spring. Every Gardener has their favourite method. The following is mine.
I use a dig method and once green manure is turned in, well rotted homemade organic compost is also added to the growing area only, gently incorporated in. Followed by ‘heel toe’ (tread) this area to firm soil. Onions are hungry bulbs, sprinkle a slow release Organic Seaweed meal, prior to giving the growing area a gentle rake. This soil prep I found helps my young plants establish themselves without too much movement of soft soil in the early days.
Spacing between onions is definitely not one spacing fits all. Onion spacing is variety dependent. For instance, Pickling variety like Silverskin can be planted as close as 3cm between bulbs/seedlings. But spacing for storage Onions like Bedfordshire Champion, 7 or 8cm is used. Such larger spacings will not only help the bulbs to grow but also help airflow around the plants and “reduce the spread’ of airborne spores like allium rust. Although the bulbs are not damaged by these spores, they take over the green leaf and stops leaves from producing chlorophyll that is vital in food production, rust damage leads to bulb sizes being reduced.
Feed and Water
Around late Spring, this is a good time to give the establishing plants a Phosphorus based feed. Phosphorous helps plants produce healthy root and shoot system. Fish, blood and Bone or Bone meal, or even Seaweed meal can be sprinkled around the base of the plants and gently worked in.
Keep the plants well watered but not water logged. If the plants experience a few days of dry roots. This can trigger the plants to bolt (send out flower stalk). Although such bulbs are edible they will not store well.
Harvest and Curing
Onions are ready to harvest around mid to late Summer. The sure tell tale signs are the bulbs are swollen and protruding out the soil and the unique brown covering forming over them. They can also have the leaf stalk flop over. When this happens, thats the perfect sign. Lift out the bulbs and allow to carry on drying out in a cool sheltered area until the leaves are completely dry. Onions can now be either plaited, strung up or simply stored in wicker baskets.
I have grown these storing Onions varieties from seed Bedfordshire Champion, Alisa Craig and Walla Walla
Note: Onions will store for up to 8 months to a year given the right storing conditions.