Cornflower

Cornflower: plant 20 cm (8 in) apart in the row and 30 cm (12 in) between rows, 4 per square. Good neighbours: Tomato, Cherry tomato, Beefsteak tomato.

Key facts

Spacing in the row	20 cm (8 in)
Between rows	30 cm (12 in)
In a 30 cm (1 ft) square	4 per square
Sun	Full sun, 6–8 hours a day
Root depth	15 cm (6 in)
Height when grown	70 cm (28 in)
Crop rotation group	Herbs, flowers and perennials
Support	None needed

Sowing and germination

How it is started	Sown straight into the bed
Seeds per hole	3
Plants kept after thinning	1
Seeds per metre of row	15
Sowing depth	1.5 cm (0.6 in)
Soil temperature	from 7 °C, best 15–21 °C
Days to emerge	7–14 days
Light while germinating	Needs darkness, cover well
Before sowing	nothing needed
When to sow	Indoors 6 weeks before the last frost; outdoors after the last frost; soil at least 12 °C

From seedling to plant

Pricking out	sown where it grows
Takes transplanting	Badly, sow where it grows
Hardening off	7–10 days
Life cycle	Annual
Cold tolerance	Hardy, takes hard frost
Soil	Light, sandy, free draining, pH 6–7.5
In a pot	5 L, 20 cm (7.9 in)
Watering	Water when the soil is dry two fingers down
Feeding	Little
Support and training	None needed; pinch the tips

Harvest and planning

Days to first harvest	65–85 days, from sowing
Ready when	The flowers are just open
Harvest window	Picked again and again, 6–10 weeks
Typical yield	0.2–0.6 kg per plant
Botanical family	Asteraceae
Watch out for	Aphids, powdery mildew

Good neighbours

Why, with the sources →

Plan Cornflower in your garden

Open the free planner, drop Cornflower onto a bed and see how many plants fit.

Start Planning Your Garden

Sowing and harvest

Sow outdoors	Apr–May
Harvest	Jun–Sep

My dates for this crop

My country Last spring frost where I live

Give the date once and this page, the sowing calendar and the planner all follow it.

Months for a temperate climate: about a month later in the north and a month earlier in the south. Give your own last frost date for exact dates.

What to plant next to Cornflower →

From the same family

Plants of the Asteraceae family share diseases and pests, so they follow each other in the rotation only after a break.

Grown much the same way

Crops that need about the same room and care, from another family.

Sources

The values on this page marked as checked come from these sources: spacing, sowing depth, germination, soil, timing and safety notes, each against the source named here.

Selected annual flowering plants for Mississippi gardens — Mississippi State University Extension for: spacing in the row; checked 2026-10-31

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