Short, perennial dahlia that grows up to 50cm tall.
Flowers and foliage
Glossy green, finely dissected leaves. Simple, daisy-like white to very pale lavender flowers. Blooms from December to March.
Prefers a sheltered position in full sun with moist, well-draining soil.
Preparation for planting
Always choose healthy, well-grown plants. The best time to plant is from late spring to early summer. Planting success can be improved on clay soils by adding extra topsoil and forming raised beds. Incorporate coarse sand, bark, compost or other organic material to improve soil structure. Dig a hole in the ground twice the size of the root ball. Before planting, ensure that the root ball is saturated and remove planter pot with minimal root disturbance. As soil is placed in the prepared hole, tread firmly to bring soil in close contact with the root ball. Water thoroughly, making sure that moisture penetrates to the depth of the root ball. In a border, plants should just touch each other to create a full effect.
Soil drainage may be improved by incorporating a generous layer of coarse sand or by adding an extra layer of topsoil to form raised beds. Before planting, incorporate generous amounts of compost or well-rotted farm manure.
Annually apply organic mulch to suppress weeds and improve soil health and moisture. Deadhead throughout the flowering season to encourage further blooming.
Let plants dry out slightly before watering. Mulch heavily and apply a balanced organic fertiliser when young plants have started to grow. Keep well-watered (Dahlia plants are almost 95% water) and feed with fish and blood and bone fertiliser during summer. Preferably, water during early morning or evening to prevent evaporation.
Remove faded blooms to prolong the flowering season but leaving a few buds to set seed to encourage seed-eating goldfinches into your garden. At the end of the season, each plant will have formed a tuber that may be left in place over the winter months if the soil is well-drained. Otherwise, tubers may be lifted and stored in sawdust or coarse sand in a sheltered spot. Dust with Flowers of Sulphur to protect tubers against disease.
Propagation of dahlias is easy, as they can be divided before replanting in spring. Buds of Dahlia tubers are restricted to the area where the old stems join the swollen tuber; this is called the crown. These buds are clearly visible when the plant is lifted and the soil is washed off. Tubers are best divided at this time, as after the tuber dries out they are not easy to see and can be damaged. Alternatively, divide in spring after the buds have started growing. New shoots may be taken as cuttings and placed in a pot or sand and kept moist. They will produce roots very quickly; keep in a pot for a few weeks and then plant it out as a green plant. Dahlias hybridise very freely, so it is important to remember that dahlias should be sourced vegetatively by cuttings and not by seed.
Ecological and biodiversity benefits
Attracts bees and birds, particularly seed-eating goldfinches.
Pests and diseases
Generously space plants for good air circulation, which prevents powdery mildew. If affected by mildew, remove fallen leaves and keep the area around the plant clean and tidy.
Viral diseases may be recognised by poor growth and mottled foliage. Destroy these plants via burning or general rubbish, as there is no controlling the spread of infection to other plants. As a precaution, always use clean secateurs, scissors or knives before moving on to the next plant when tying, trimming or deadheading.
Dahlias may also be affected by caterpillars and leaf spot. In spring, new shoots are often susceptible to slug and earwig damage. To control earwigs, place dry grass in a plant pot and hang upside down on a cane and place by the plant. The earwigs will hide in the dry grass so you can collect and dispose of them.
Location at Auckland Botanic Gardens