🧅 Onion 'Ailsa Craig'

Sowing window (UK)	January to March
Minimum soil temperature	5°C at seed depth
Sowing depth	1 cm
Spacing	30 cm apart
Days to germination	14 days
Days to harvest	168 days
Sowing method	Start under cover, transplant out
Frost hardy	Yes
Sun	full-sun
Watering	low
Plant family	Amaryllidaceae

When should I sow Onion 'Ailsa Craig' in the UK?

In the UK, sow Onion 'Ailsa Craig' from January to March. It is normally started under cover and transplanted. Wait until the soil has reached 5°C at seed depth rather than going by the calendar - onion will sit and rot in cold ground.

What soil temperature does Onion 'Ailsa Craig' need to germinate?

Onion 'Ailsa Craig' needs a minimum soil temperature of 5°C at seed depth to germinate reliably. Below that, germination is slow and patchy, and seed is more likely to rot than sprout. Measure at around 5cm down, in the morning, rather than trusting air temperature.

How deep and how far apart should I sow Onion 'Ailsa Craig'?

For Onion 'Ailsa Craig', sow it 1cm deep and space plants 30cm apart.

How long does Onion 'Ailsa Craig' take to grow?

Onion 'Ailsa Craig' takes roughly 168 days from sowing to harvest. Seed usually germinates in about 14 days.

Is Onion 'Ailsa Craig' frost hardy?

Yes. Onion 'Ailsa Craig' is frost hardy and will stand through UK frosts, so it can be left out over winter in most of the country.

Sowing data cross-checked against RHS growing guides and UK seed-merchant catalogues. Soil temperatures are the minimum for reliable germination, measured at seed depth.