GARDENING: Know your onions this Christmas

PERFECT SPECIMENS: Prize winners at Harrogate Autumn Show.
PERFECT SPECIMENS: Prize winners at Harrogate Autumn Show.

THERE’S a lot of folklore around sowing onion seeds, the most popular one being that the biggest bulbs are grown from those sown on Boxing Day -­ or even Christmas Day.

Of course, there’s a lot of truth in this, especially if you want onions for the exhibition bench in September ­- they need all that time to grow so large!

However, you can still use this method for alliums that will end up in your kitchen - it’s a nice little job away from the festivities.

Bear in mind, though, this is for onions from seed only -­ sets are started off in spring.

If you really want to put your feet up, you can sow right through to February,­ but expect smaller bulbs.

For best results, choose varieties such as Wellington, Red Sunrise, Kelsae, Robinson’s Mammoth, Rose de Roscoff, Bedfordshire Champion or Red Pearl.

To sow, fill a seed tray or cell insert with good­ quality seed compost and tamp down the surface, then water in - watering now means you won’t disturb the spacing of the seeds.

With cell trays, sow four or five per compartment, sow thinly in a standard tray, then lightly cover with 5mm (1⁄4”) more compost.

Cover the tray with a propagator lid, or sheet of glass/polythene.

The ideal germination temperature is 15­20°C (60­68°F), but it should not be lower than 15°C (60°F).

After germination, remove the cover and move to an area with plenty of light. Keep the compost damp.

Maintain a temperature of about 18°C (65°F) until “crook stage” (when the seedling is still looped over like a shepherd’s crook, with the tip of the seed leaf still in the compost, usually two-­three weeks after germination, just before the second leaf).

After this, place them somewhere cooler, reducing the temperature to 10°–13°C (50­55°F).

The seedlings need maximum light and ventilation until the pricking out stage, but be careful of scorching from direct sunlight.

Transfer boxes and trays to a cold frame in March or April.

THE pagan midwinter festival was handily incorporated into the Christian church by creating the feast day of St Thomas on December 21.

Various perennial onions are now called “St Thomas’s onion”, traditionally planted on the shortest day (December 21) and harvesting at the summer solstice (June 21).

The name variously applies to the potato onion (Allium cepa); Egyptian onion (Allium cepa aggregatum) and the Welsh onion (A. fistulosum).

They’re all propagated by offsets, not seed, crop three months earlier than other varieties and are not attacked by onion fly.

I grow a heritage variety of the Welsh onion, Ciboule Red, which is very handy, a bit like spring onions but stronger.

They’re decorative, so worth it if you don’t have much space.

For more gardening tips and advice, visit Mandy’s website HERE.