Growing Onion

Jan F M A M J J A S O N Dec
  S   T P P S   T      

(Best months for growing Onion in New Zealand - cool/mountain regions)

S = Plant undercover in seed trays T = Plant out (transplant) seedlings P = Sow seed

  • Easy to grow. Grow in seed trays, and plant out in 4-6 weeks. Sow seed at a depth approximately three times the diameter of the seed. Best planted at soil temperatures between 8°C and 30°C. (Show °F/in)
  • Space plants: 5 - 10 cm apart
  • Harvest in 25-34 weeks. Allow onions to dry before storing.
  • Compatible with (can grow beside): Lemon Balm, Borage, Carrots, Beets, Silverbeet, Lettuce, Amaranth
  • Avoid growing close to: Peas, Beans

Your comments and tips

12 Feb 21, Rosie (Canada - Zone 5b Temperate Warm Summer climate)
How do you care for onion plants: weeding, cutting back,spooning,fertilizing,watering?
02 Mar 21, (Canada - Zone 5a Temperate Warm Summer climate)
Start with good loose soil that has had some fertiliser, compost, manure put in it, don't over do it though. Water every day when small and then each 2 days when half grown. Keep weeded.
03 Feb 21, Sky Kell (USA - Zone 7b climate)
Perennial onion that multiplies for 7b zone
18 Dec 20, Sydney Thama (South Africa - Summer rainfall climate)
hello it is safe to plant onion around July and August?
21 Dec 20, Anon (South Africa - Summer rainfall climate)
Go the onion page and check when to plant onions in your climate zone, or google and research about growing onions.
13 Oct 20, Kelly (South Africa - Summer rainfall climate)
Hi there, I planted white onions in May, they have not yet yellowed and the stalks have not fallen over- we're having a lot of rain fall early on and I am afraid they will rot if I leave them in the ground while it rains so much. Can I harvest them before they have yellowed or will they still mature correctly despite the rain? Any tips or advice would be much appreciated Thanks
16 Oct 20, (South Africa - Summer rainfall climate)
It says plant seed Feb Mar and you planted May, that is the problem. Check to see how big they are, if a good size pull out. You be the judge, keep an eye on them, if they look like going rotten out they come.
13 Oct 20, Liesl Mittan (South Africa - Summer rainfall climate)
We planted onions late in march , they are ready and some are flowering .They should dry in the ground , but we are having rain. What do I do . Take them out and dry them hanging or leave in the ground and hope for hot weather . Thanks
19 Oct 20, (South Africa - Summer rainfall climate)
Pull them out.
10 Sep 20, Vicky (South Africa - Summer rainfall climate)
I planted red onion seedlings in April. I was waiting for the tops to bend over, as I've read. But now they're flowering. When should I have harvested? Also. The necks are very thick.
Showing 21 - 30 of 287 comments

Can I plant onion sets in February or march? what sweet onion varieties do you suggest for No. Ca. marine zone 9B? Thank you.

- Judith c Greenleaf

Please provide your email address if you are hoping for a reply


All comments are reviewed before displaying on the site, so your posting will not appear immediately

Gardenate App

Put GardenGrow in your pocket. Get our app for iPhone, iPad or Android to add your own plants and record your plantings and harvests

Planting Reminders

Join our 60,000+ gardeners who already use GardenGrow and subscribe to the free GardenGrow planting reminders email newsletter.


Home | Vegetables and herbs to plant | Climate zones | About GardenGrow | Contact us | Privacy Policy

This planting guide is a general reference intended for home gardeners. We recommend that you take into account your local conditions in making planting decisions. GardenGrow is not a farming or commercial advisory service. For specific advice, please contact your local plant suppliers, gardening groups, or agricultural department. The information on this site is presented in good faith, but we take no responsibility as to the accuracy of the information provided.
We cannot help if you are overrun by giant slugs.