🌻 Sunflower 'Giant Single'

Sowing window (UK)	April to May
Minimum soil temperature	10°C at seed depth
Sowing depth	3 cm
Spacing	45 cm apart
Days to germination	10 days
Days to harvest	100 days
Sowing method	Direct sow outdoors
Frost hardy	No
Sun	full-sun
Watering	moderate
Plant family	Asteraceae

When should I sow Sunflower 'Giant Single' in the UK?

In the UK, sow Sunflower 'Giant Single' from April to May. It is normally sown direct outdoors. Wait until the soil has reached 10°C at seed depth rather than going by the calendar - sunflower will sit and rot in cold ground.

What soil temperature does Sunflower 'Giant Single' need to germinate?

Sunflower 'Giant Single' needs a minimum soil temperature of 10°C at seed depth to germinate reliably. Below that, germination is slow and patchy, and seed is more likely to rot than sprout. Measure at around 5cm down, in the morning, rather than trusting air temperature.

How deep and how far apart should I sow Sunflower 'Giant Single'?

For Sunflower 'Giant Single', sow it 3cm deep and space plants 45cm apart.

How long does Sunflower 'Giant Single' take to grow?

Sunflower 'Giant Single' takes roughly 100 days from sowing to harvest. Seed usually germinates in about 10 days.

Is Sunflower 'Giant Single' frost hardy?

No. Sunflower 'Giant Single' is not frost hardy. Do not put it outside until the risk of frost has passed in your area, and be ready to fleece it if a late frost is forecast.

Sowing data cross-checked against RHS growing guides and UK seed-merchant catalogues. Soil temperatures are the minimum for reliable germination, measured at seed depth.