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.
The dahlia does not take frost, so planting splits into two routes. A dormant tuber goes straight into the bed in the first part of the window, because the ground is no longer frozen by then and the shoot comes up only weeks later. Plants started off indoors go out towards the end, once the frosts are over.
The tuber is laid flat on the bottom of the hole and covered with only a little soil at first. The rest of the hole is filled in gradually as the shoot grows.
The dahlia flowers without a break until the first frost stops it. Blackened leaves are the sign that it is time to lift. In heavy, wet ground the tubers rot over winter. They are kept dry, in a dark, cool place where it never freezes.
Dahlias through the year
- planting
- flowering
In short
Growing conditions
Are dahlias toxic to cats and dogs?
Yes. 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.
- 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.
- What to do
- Potassium soap works on contact and only while it is wet, so it has to reach the underside of the leaf. On drought-loving plants and in heat it can scorch, so apply it in the evening.
- 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.
- What to do
- Oil products meant for powdery mildew on the squash family work on contact. They do not cure a leaf that is already affected, but they stop the spread to healthy ones. On herbs cut the affected shoots back instead, since the new growth comes clean. On ornamental perennials what is left is spacing and moisture.
- 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.
- What to do
- Baits with iron phosphate are held to carry less risk for pets and children. Put them out in bands beside the bed, not scattered over the whole surface.
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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.