When should I sow cut flower seeds in New Zealand?
In most of New Zealand, sow your summer cut flowers from late September through to December, and plant them out into the garden after your last frost. Labour Day in late October is the traditional guide. Hardy varieties like snapdragons and scabiosa can go in earlier, in autumn or very early spring, because a bit of cold does not bother them.
Hi, I am Rachel. I grow cut flowers on my farm in Peacocke, just south of Hamilton, and this is the question I am asked more than any other. Usually in about July, by someone who has just realised they would like flowers next summer and is not sure whether they have left it too late.
You have not. If it is winter as you are reading this, you are early, and early is exactly where you want to be.
What is the difference between sowing and planting out?
This trips people up more than anything else, so let us get it clear first.
Sowing is putting the seed into a tray or pot to germinate. You can do this while it is still cold outside, because the tray lives somewhere sheltered and warm.
Planting out is moving the seedling into the garden. This is the one that has to wait for frost to pass.
So you get a head start by sowing in late September while the mornings are still cold, and by the time Labour Day rolls around you have got sturdy seedlings ready to go in, rather than a packet of seeds and a lot of hoping.
When is the last frost in the Waikato?
Around Hamilton the last frost usually falls in September or early October, though it moves about year to year and it is colder out in the rural areas than it is in town. Labour Day weekend, the last Monday in October, has been the New Zealand gardener's rule of thumb for generations for good reason. By then you are almost always clear.
If you are somewhere colder, Central Otago or the Central Plateau, give it another two or three weeks. If you are up north in Auckland or Northland you can push earlier.
The flowers I sell are all frost tender. One cold night after planting out will undo weeks of work, so when in doubt, wait the extra week. The plants catch up fast in warm soil.
What is the month-by-month sowing calendar?
July and August. Nothing to sow yet for summer. This is planning time. Work out where your sunny spot is, order your seeds so they are sitting on the bench ready, and get some compost into the bed if the ground is not too wet to work.
Late September. Start sowing indoors or under cover. Zinnias, cosmos, celosia, matricaria and snapdragons all go into trays now. Somewhere warm and bright, a sunny windowsill is perfect.
October. Keep sowing. Seedlings from your September sowing will be ready to harden off. After Labour Day, start planting out.
November. Plant out everything that is ready. You can still sow more, and honestly you should, because a second sowing three or four weeks behind the first is what keeps you in flowers right through to autumn instead of having everything peak at once.
December. Last call for sowing summer annuals. Anything sown now will flower late in the season, which is no bad thing when everything else is starting to look tired.
January to March. Picking season. Cut hard and cut often.
Autumn. Sow the hardy ones. Snapdragons, scabiosa and matricaria can go in now for an earlier show next year.
How long from sowing until I have flowers?
Most summer annuals take eight to twelve weeks from sowing to first bloom. Seeds in a tray in late September usually means flowers on your kitchen table by Christmas or early in the new year.
Germination itself is quick, five to fourteen days for most of what I grow. It is the growing on that takes the time.
How do I sow cut flower seeds, step by step?
- Fill your trays with seed raising mix and moisten it. Damp, not soaking. You do not need fancy trays, clean shallow containers that drain will do the job.
- Press the seeds onto the surface. Zinnias and cosmos get a fine layer of soil over the top. Matricaria stays uncovered because it needs light to germinate. Snapdragons and celosia get a light dusting of vermiculite if you have it.
- Cover with a dome lid or cling film to hold the humidity in.
- Put them somewhere warm and bright. A sunny windowsill or a sheltered porch.
- Water gently. A spray bottle, or sit the tray in a shallow dish of water and let it drink from below. Moist, never soggy.
- Take the cover off once the seedlings are up, usually five to fourteen days.
- Harden them off when they are 5 to 8cm tall with a few sets of true leaves. Put them outside during the day for about a week so they toughen up.
- Plant out in full sun after your last frost, 20 to 30cm apart. Closer than the packet says is fine for cut flowers, it encourages long straight stems.
What should I do right now if it is the middle of winter?
Order your seeds. That is genuinely it.
Every packet I sell has the New Zealand sowing timing printed on it for that variety, so once they are in your kitchen drawer you do not have to remember any of this. And there is a real advantage to having them early. Come late September you will be sowing on the right weekend rather than waiting on a delivery.
If you are not sure what to start with, my Cut Flower Seed Kit has five varieties I have picked because they are forgiving. Zinnias, cosmos, matricaria, celosia and snapdragons. It is the kit I would hand a friend who told me they had never grown anything.
Frequently asked questions
When should I sow cut flower seeds in New Zealand?
Sow summer varieties like zinnias, cosmos and celosia from late September through December, and plant out after your last frost. Labour Day in late October is the usual guide. Hardy varieties like snapdragons and scabiosa can be sown earlier in autumn or very early spring.
Can I sow cut flower seeds in winter?
Not the summer annuals. They are frost tender and will not survive a cold snap. Winter is for planning and for getting your seeds ordered so you are ready to sow in late September.
Do I have to start seeds indoors?
No, you can direct sow into warm soil once the frosts have passed. Starting in trays gives you a head start and protects the seedlings from slugs, but plenty of flowers get grown the simple way.
How long do cut flowers take to grow from seed?
Eight to twelve weeks from sowing to first flower for most summer annuals. Germination takes five to fourteen days.
Is it too late to sow in December?
No. A December sowing gives you late-season flowers when everything else is going over. I sow in waves right through the season for exactly that reason.
