How to grow Cornflower in New Zealand
Cornflower (Centaurea cyanus) is a hardy cottage-garden annual best known for its brilliant true-blue flowers, though there are also black, plum, pink and white forms. It is easy from seed, rich in nectar for bees, butterflies and hoverflies, and makes a long-lasting cut flower. The petals are edible, with a mild, clove-like flavour.
📖 Our full guide: How to Grow Cornflower in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | August to October, January to April | |
| Auckland | August to October, January to April | |
| Waikato & Bay of Plenty | August to October, January to April | |
| Central North Island | August to October, January to April | |
| Wellington & Lower North Island | August to October, January to April | |
| Nelson & Marlborough | August to October, January to April | |
| Canterbury | August to April | Sow Aug to Apr. Cover early sowings with a cloche or frost cloth, as frosts run to mid October. Get the last sowing in by Apr so it sizes up before winter growth stops. |
| Otago & Southland | August to April | Sow Aug to Apr. Cover early sowings with a cloche or frost cloth, as frosts run to late October. Get the last sowing in by Apr so it sizes up before winter growth stops. |
| Central Otago | August to April | Sow Aug to Apr. Cover early sowings with a cloche or frost cloth, as frosts run to early November. Get the last sowing in by Apr so it sizes up before winter growth stops. |
Where to plant
Sow cornflowers in full sun in well-drained soil. They are hardy and easy, and do not need rich soil. In milder gardens, autumn sowings overwinter as small plants and flower early in spring; spring sowings flower in summer.
- Northland, Auckland, Waikato and Bay of Plenty, the central North Island, Wellington, and Nelson and Marlborough: sow from August to October and from January to April.
- Canterbury, Otago and Southland, and Central Otago: sow from August to April, covering early sowings with a cloche or frost cloth, and get the last sowing in by April.
Choosing a variety
- Blue Boy and Dwarf Blue: the classic sky-blue cornflower. Dwarf Blue grows to 30 to 45 cm and suits containers and bedding.
- Black Ball: deep maroon-black double flowers on tall stems, good for cutting and drying.
- Classic Magic Mix: black, deep plum and purple-and-white bicolour flowers to about a metre tall.
How to plant
- Sow seed about 0.5 cm deep directly where it is to flower, or in trays to transplant.
- Keep moist; seedlings appear in 7 to 14 days.
- Thin or plant out about 20 cm apart.
- Stake or support tall varieties in windy spots.
Watering and feeding
Water seedlings until established, then only in dry spells. Cornflowers need little feeding.
Pruning and care through the year
- Pick and deadhead regularly to keep the plants flowering over a long season.
- Leave a few heads to set seed if you want cornflowers to self-sow for next year.
Harvesting
Cut flowers for the vase when they are just opening. For eating, pick open flowers on a dry day and pull the petals. Fresh flowers are best used within two days; dried petals keep for months in a sealed jar.
Growing in pots
Dwarf cornflowers grow well in a pot at least 20 cm wide in full sun, in quality potting mix. Keep the mix moist and pick often.
Using it
Scatter the petals over salads, cakes and drinks, or dry them for colour in tea blends. Cornflowers are long lasting in the vase and dry well.
Companion planting
Cornflowers are traditionally grown among wildflowers and grains, and they bring pollinators to any part of the garden.
Good companions
- Wildflowers Cornflowers are a classic part of a meadow or wildflower mix.
- Grains Historically a cornfield flower, which is how it got its name.
Pests and diseases
Cornflowers are easy and rarely troubled.
Pests to watch for
Diseases to watch for
- Powdery mildew White powdery coating on the leaves, usually late in the season.
Common questions
When do I sow cornflowers in New Zealand?
From August to October and January to April in most regions. Autumn sowings flower early in spring in milder gardens. In Canterbury and the south, sow from August to April, covering early sowings.
Are cornflowers edible?
Yes. The petals have a mild, clove-like flavour and are used to decorate salads, cakes and drinks.
Do cornflowers come back every year?
They are annuals, but they self-seed readily if you leave a few flowers to set seed.
How do I keep cornflowers flowering?
Pick and deadhead regularly. Cornflowers keep flowering for a long time if the flowers are cut.
Are cornflowers good for bees?
Yes. They are rich in nectar and attract bees, butterflies and hoverflies.
Sources we checked: Kings Seeds: Cornflower Classic Magic Mix; Kings Seeds: Cornflower Dwarf Blue.