Originating in Mexico, Scotland would not seem the most obvious place for dahlias to thrive and yet we love them! Staging a big comeback in recent years in gardens across the country, the newfound popularity of dahlias looks set to continue in our borders and containers.
Although the range of dahlias appears huge, they are grouped into categories depending on the flower type: cactus types with spiky petals; compact pom pom or ball types; collarettes with a single row of petals surrounding an open centre; orchid, peony, waterlily, and anemone-flowered options; and the double flower-headed ones known as decoratives. These incredibly varied plants offer something for everyone in terms of shape, size, and colour.
You can order dahlias as dormant tubers from January onwards but at this time of year, you can buy them from any good garden centre or nursery and in a sunny spot, they will provide high-impact late summer colour which will last right through until the first frosts.
Often tarred with a reputation of being fussy to over-winter, dahlias are easy to see through to next year by following these top tips!
- Dahlias are tender perennials so in our Scottish gardens, which are not just cold through winter but also wet, it is best to lift and store them.
- Dig the tubers up after a hard frost by November, cut off the top growth to around 10cm, and shake off any excess soil.
- Store upside down indoors for a couple of weeks to let excess moisture drain from their hollow stems then store them in dry compost, chipped bark, or shredded paper in a dark, frost-free place like a garage. Remember to label them, as it is not easy to remember which brown tuber is which come next year.
- Dahlias grow fresh from tubers every year and tubers can be planted in pots at a depth of around 10cm from April onwards.
- Water sparingly until signs of growth appear then begin watering more frequently.
- Dahlias should not be set outside until after the last frosts and should be hardened off for a few days before planting out.
- Give them a little space when planting out to allow them to grow well.
- Medium to tall dahlias will generally need staked and the most common method of doing this is by using a circle of bamboo canes and twine around the plant.
- Feed dahlias with a high potash feed every two weeks to maintain flower production.
- Cutting or deadheading the plant will encourage the plant to produce more flowers.