Dahlias are wonderful plants and can bring prolonged colour to your garden over the summer months. Place the tubers (half covered with compost), in a warm sunny place like a heated greenhouse or windowsill. New shoots should appear in 2-3 weeks and the plants will be ready for potting up into 1 litre pots to grow on until the danger of frosts have subsided. Alternatively, plant the un-sprouted tubers about 10cm deep in the border you’ve chosen to plant them in around 6 weeks before the last frosts.
Before planting stakes should be firstly placed into the ground followed by the tubers. This will prevent spiking the tubers with your stakes. Good to keep in mind when planting anything requiring support – always best to put the support in before the plant – that way you avoid unnecessary damage to the plant. Most ideal are three canes positioned around a tuber or tubers with string between them to form a triangular support to contain and support them within this framework.
Dahlias are greedy feeders, so apply a good helping of general fertilizer. Dahlias will produce more flowers if they are “stopped” once they have reached about 40-50cm tall encouraging the plant to bush out. Pinch out the main growing tip above the top pair of leaves.
Dahlias produce a mass of delicate roots, which are found just under the soil surface. In midsummer it is well worth mulching well, around the base of plants with a layer of well rotted down compost. In full growth they will need a good soaking with water every other day. Water at the base of the plant and never overhead as this will damage the flowers. It is always best adopting a watering programme either early in the morning or late afternoon/early evening. This will help the plant to benefit from most of the water – in the heat of the day a lot will evaporate or cause scorching of the leaves. To prolong flowering, don’t forget to deadhead regularly, by cutting above the next bud down the stem.
