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Quick Facts
- Sowing window
- Sow indoors from January to March or direct outside in March to April.
- Harvest window
- Lift flattened red bulbs in late summer once the tops fall.
- Difficulty
- Easy to moderate
- Container suitability
- Use a container at least 25–30cm deep. Space bulb onions 8–10cm apart and leeks 15cm apart; a rectangular trough makes the best use of limited space.
- Frost sensitivity
- Generally hardy
- Typical time to harvest
- Bulb onions usually need five to seven months; winter leeks can stand for longer and be lifted as required.
SOW
When to Sow Red Onion Brunswick in the UK
Sow indoors from January to March or direct outside in March to April.
Use that window as a practical starting point rather than a fixed deadline. In colder or exposed areas, delay outdoor sowing and planting; in mild sheltered areas, the earlier end of the range may work. Tender crops should remain protected until frost risk has passed.
Sowing Indoors
Early bulb onions and leeks can be sown in modules under cover. Give seedlings maximum light and plant out once sturdy; spring onions are normally simpler sown direct.
Sowing Outdoors
Sow Red Onion Brunswick thinly in prepared soil or its final container. Keep the seedbed weed-free because fine young allium leaves compete poorly.
PLANT
Spacing and Planting Out
Space bulb onions 8–10cm apart and leeks about 15cm apart, with 25–30cm between rows.
Before planting outside, harden off indoor-raised plants over 7–10 days unless the crop is fully hardy and already accustomed to outdoor conditions. Water the planting hole or container first and avoid leaving young roots exposed to sun or wind.
SMALL SPACES
Growing Red Onion Brunswick in Pots and Containers
Use a container at least 25–30cm deep. Space bulb onions 8–10cm apart and leeks 15cm apart; a rectangular trough makes the best use of limited space.
Container checklist
- Use drainage holes and raise pots slightly so surplus water can escape.
- Fill with fresh peat-free compost suited to edible crops.
- Leave a watering lip below the rim and check pots more often in sun or wind.
- Use a strong support at planting time if the mature crop will climb or become top-heavy.
CARE
Watering and Feeding
Water during dry spells while plants are actively growing, then reduce water as bulb onions mature. Avoid heavy nitrogen feeding late in the season because soft growth stores poorly.
Variety note: Dry bulbs in a warm airy place before storage and stop watering as they mature.
WATCH FOR
Common Problems
Allium leaf miner
Cover crops with fine insect mesh during adult flight periods and do not leave gaps at soil level.
Onion fly
Wilting seedlings can indicate maggots at the roots. Rotate crops and remove affected plants.
Rust
Orange pustules spread in crowded, damp foliage. Improve spacing and avoid excessive nitrogen.
PICK
Harvesting Red Onion Brunswick
Lift flattened red bulbs in late summer once the tops fall.
Bulb onions usually need five to seven months; winter leeks can stand for longer and be lifted as required. Harvest in the coolest part of the day where practical and handle produce gently. Regular picking encourages continued cropping in fruiting and cut-and-come-again plants.
GROW TOGETHER
Companion Plants
Carrots, lettuce and beetroot can share a wide bed or nearby containers where spacing allows. Companion combinations are useful for planning, but mesh is more dependable against allium pests.
QUESTIONS
Frequently Asked Questions
Can I grow Red Onion Brunswick in pots?
Use a container at least 25–30cm deep. Space bulb onions 8–10cm apart and leeks 15cm apart; a rectangular trough makes the best use of limited space.
How long does Red Onion Brunswick take to harvest?
Bulb onions usually need five to seven months; winter leeks can stand for longer and be lifted as required.
Why are my Red Onion Brunswick seedlings falling over?
Weak light, crowded sowing, overwatering or damping-off can all weaken seedlings. Increase light and airflow and water from below when possible.