sunflower

When to sow sunflowers?

Botanical name
Helianthus annuus
Family
Asteraceae

Sunflowers are sown from May to June. They flower from July to September.

Sunflowers are annual plants. The edible parts are the flowers and seeds.

sunflower
Photo: Tomascastelazo · CC BY-SA 4.0

Sunflowers through the year

JanFebMarAprMayJunJulAugSepOctNovDec
Sowing
Planting
Flowering
15913172125293337414549
  • sowing
  • planting
  • flowering

In short

Sowing
from May to June
weeks 20 to 23
the window opens at the last frost
Planting
from May to June
weeks 21 to 24
the window opens a week after the last frost
Flowering
from July to September
weeks 28 to 37
Propagation
seed

The last frost is not on the same day everywhere, so the recorded weeks are a guide and not a date.

Growing conditions

🧪
pH
6 to 7.5
☀️
Sun
full sun
💧
Water
moderate water
❄️
Frost
does not tolerate frost
📏
Height
0.46 to 3.05 m

Companions in the bed

Companion planting is tradition and not an agronomic claim. What is recorded is which pairs sources recommend and which they advise against.

bean cited

The sunflower is a living support instead of a pole. It works only if it is sown a few weeks earlier.

cucumber cited

The sunflower as a living support. It works only if it is sown a few weeks earlier.

  • “Cited” means the pair is named by one source or two.

Pests and diseases

Listed here is every problem for which the sources name this plant as a host. The problems are not listed in order of how common they are.

Powdery mildew

disease
Signs
A white, floury coating spreads over the leaves, first on the lower and older ones. The leaf under it yellows and dries up. The fruit stays small, because the plant loses leaf surface.
Prevention
Plant resistant varieties, leave an airy spacing and sun, and clear the debris at the end of the season. Unlike most fungi it is not helped by wet foliage, since it spreads in heat and high air humidity, in a dry summer too.

Slugs and snails

pest
Signs
Holes appear in the middle of the leaf rather than along the edge, young plants are eaten down to the ground, and there are slimy trails in the morning. On low-growing fruit there are gnawed pits.
Prevention
Remove the hiding places beside the bed: boards, stones, dense weeds. Water in the morning and not in the evening, so that the night is dry. Spread a band of coarse sand or gravel around the bed. Cover young plants with fleece. Pick them off at night, which is still the most effective measure.

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Related plants

The plants below are in the same botanical family (Asteraceae).

Sources about the plant: Clemson Cooperative Extension, GBIF Backbone Taxonomy, NC State Extension Plant Toolbox, Royal Horticultural Society, Utah State University Extension, Wikidata. Checked between 14 and 28 August 2026. The problem descriptions also draw on: KGZS, UF/IFAS Extension, University of Maryland Extension, University of Wisconsin-Madison Division of Extension.