Use : Outdoors
Evergreen/Deciduous : Deciduous
Plant Type : Bulb
Flower Colour : Varied
Foliage Colour : Green
Best Season : Mid Summer to Autumn
Light : Sun
Hardiness : Semi-hardy
Attributes : Cut Flower
Height (m) :
Spread (m) :
Decorative Cactus Dahlia
Notes : Genus of about 30 000 species with some 20 000 cultivars. Although it is only about two hundred years since the Dahlia arrived from Mexico, today it is one of the most popular Summer plants. Colours range from white to red, orange to yellow, pink to dark purple and shades thereof. Plants are short with medium-sized blooms. Make a good display in a mixed border from mid-Summer right until the first Winter frost strikes and are excellent for the vase.
Dead-head as flowers fade. Plant tubers in late Spring, when the soil has warmed, in a hole approximately 30 centimetres deep and wide. Add compost and well-rotted manure to half the soil removed from the hole. Place about a 5 centimetre layer of soil mix in the bottom and then about a 5 centimetre layer of river-sand. The sand ensures good drainage which is essential for bulbs. Place the tuber on the sand with the short, dry stalk pointing upwards. Fill the hole with the remaining soil. Insert a stake or cane right next to the tuber. Water well immediately after planting.
Always keep moist by watering deeply once a week or whenever the soil starts to dry out. It may take 6 -to 8 weeks before any growth becomes visible above ground level. Prefer bright sunshine, but will perform reasonably in light shade if they receive at least 3 to 4 hours of sunshine a day. The more sun they get, the sturdier the plants will be. Pruning and disbudding is necessary if good blooms are to be grown. The plant should be confined to just a few stalks with most of the side shoots being pinched out.
Staking should be maintained as the plant grows. As the flower buds appear most of the lateral buds should be removed, leaving mostly single flower buds per stem. Dahlias are gross feeders. Will benefit from a weekly feed with a high nitrogen liquid fertiliser in early Summer and then a weekly feed of a high potash fertiliser from mid-Summer to early Autumn. Mulch heavily with well-rotted manure just as the buds form. In mid-Autumn once the foliage has died down, cut back and lift tubers.