Onion should be ready to harvest this month. Check for size and colour.
Growing Calendar
This month: Sep
Log to journalReady to harvest now
- •Check size and ripeness
- •Harvest regularly
- •Store or use fresh
Watch Out For
Onion fly lays eggs near the base: use enviromesh or fine fleece to exclude flies from late March onwards
Neck rot in storage: ensure bulbs are fully dry in the sun for at least 2 weeks before storing in a cool dry place
Bolting if sets are planted into cold, wet soil: wait until the soil has warmed slightly and hold back if the forecast is wet; cold-planted sets almost always bolt
Grown Organically
Every method in this guide works with natural systems: no synthetic chemicals, no shortcuts.
Read our approachCommon Questions
About growing Onion in the UK
Should I grow onions from seed or sets in the UK?
Sets (small bulbs) are much easier and quicker. Plant from March to April and harvest from July. Seeds give more variety choice and can be cheaper for large quantities, but take longer and need more care. For beginners, sets are the best starting point.
Why are my onions falling over?
Onions naturally fall over when the bulbs are maturing: the leaves yellow and collapse, which signals the bulbs are ready to harvest. This is normal and expected, usually from July onward.
How do I store onions after harvest?
After harvest, dry onions thoroughly in a warm, airy place for 2–4 weeks until the skins are papery. Store in net bags, plaited strings, or slatted trays in a cool, dry, frost-free place. Well-cured onions keep for 4–6 months.
Can I grow onions in containers?
Yes, but use a deep container (at least 20cm) and plant sets 10cm apart. Yield will be lower than in open ground, but containers work well for small spaces. Use a fertile, free-draining compost.
Written from real growing experience, not just research. Read the story behind Pelham Gardens.
Member guides
There's more to growing Onion than this guide covers.
A Garden Journal to log what worked, a personalised sowing planner in My Garden, and monthly reminders timed to the calendar.
