dahlia

When to plant dahlias?

Botanical name
Dahlia
Family
Asteraceae

Dahlias are planted from April to June. They flower from July to October.

Dahlias are perennial plants.

dahlia
Photo: Joydeep · CC BY-SA 3.0

Dahlias through the year

JanFebMarAprMayJunJulAugSepOctNovDec
Planting
Flowering
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  • planting
  • flowering

In short

Planting
from April to June
weeks 16 to 23
Planting depth
15 cm
Flowering
from July to October
weeks 27 to 42
Propagation
division and cuttings

Growing conditions

🪨
Soil
loamy
☀️
Sun
full sun
💧
Water
plenty of water
❄️
Frost
does not tolerate frost
🧣
Overwintering
must come indoors
📏
Height
30 to 183 cm
⚠️
Toxicity
toxic to people and animals, toxic parts: tubers and leaves

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.

Aphids

pest
Signs
Colonies of small aphids sit on the shoot tips and the underside of the leaves. The leaf curls and puckers, and sticky honeydew is left on everything below. The viruses they carry are more dangerous than the feeding itself.
Prevention
Go easy on nitrogen, because soft sappy growth is what aphids are looking for. Encourage the predators (ladybirds, lacewings, parasitic wasps). Use a reflective mulch, which puts them off settling, and a strong jet of water to knock the colony off the tips.

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. If you do not let it go thirsty in a drought, it is less frequent.

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