- Very easy to grow - sow them in rows 4 inches apart, and thin the seedlings (if necessary) to about 1 inch apart.
- White Lisbon is the commonest variety, and should be sown in short rows in succession from March right through the season. It can also be sown in mid/late summer to overwintering for a spring crop.
- Try some other varieties - Ramrod is winter hardy and can also be sown in autumn; Ishikura doesn't form bulbs and needs fewer successional sowings.
Varieties I've tried.
Variety
About
Results
Purplette
Spring Onion (red)
Looks better, tastes better, and crops better than the standard White Lisbon - a good find in 2002. Leave it long enough, and it will form bulb onions suitable for pickling.
Ramrod
All summer; also winter hardy
Bed vandalised.
White Lisbon
All summer
Doesn't do particularly well for me - slow and small. Not impressed!
Growing Calendar - Spring and Salad Onions
Timings are based on my allotment in Yorkshire; southerners will start earlier, northerners even later!
Should fit in Onion part of your rotation.