🧅 Welsh Onion

Sowing window (UK)	March to May
Minimum soil temperature	5°C at seed depth
Sowing depth	1 cm
Spacing	30 cm apart
Days to germination	14 days
Days to harvest	60 days
Sowing method	Direct sow outdoors
Frost hardy	Yes
Sun	full-sun
Watering	low
Plant family	Amaryllidaceae

When should I sow Welsh Onion in the UK?

In the UK, sow Welsh Onion from March to May. It is normally sown direct outdoors. Wait until the soil has reached 5°C at seed depth rather than going by the calendar - welsh onion will sit and rot in cold ground.

What soil temperature does Welsh Onion need to germinate?

Welsh Onion 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 Welsh Onion?

For Welsh Onion, sow it 1cm deep and space plants 30cm apart.

How long does Welsh Onion take to grow?

Welsh Onion takes roughly 60 days from sowing to harvest. Seed usually germinates in about 14 days.

Is Welsh Onion frost hardy?

Yes. Welsh Onion 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.