Once the young plants have become established, they make rapid growth, and it is important that the new growth is securely tied.
A common method of supporting rapidly growing dahlia plants is to insert two further canes at an angle to each plant and then tie twine around the three canes at intervals to form an inverted funnel which will hold the plants firmly despite the strongest winds.
An alternative method is to use wire or plastic netting with a six inch mesh tied horizontally to the canes about two feet above ground. The plants grow through the netting and are secure against the strongest winds.
It is important to keep the plants weed free, and regular hoeing also keeps the soil open. However, by the end of June, surface feeder roots develop, and then hoeing must stop. Persistent weeds will then have to be removed by hand.
Further weeding can be eliminated by applying a mulch to the soil.
A vast array of materials is available for mulching from straw to spent mushroom compost, even old carpet has been used successfully. Before applying the mulch, it is important that the soil is wet, and if no rain is expected, the soil should be given a good watering.
During early summer, the plants will make considerable growth and this will attract heavy infestations of aphids. A big danger is the spread of viruses brought in by aphids, and it is important to set up a regular spraying programme using a range of insecticides. Plants should be sprayed every fortnight, preferably with a different insecticide each time, to ensure that the aphids do not build up any resistance to a single insecticide. Earwigs are often a problem with dahlias as they are difficult to control with sprays. They are best dealt with by trapping using an inverted flower pot filled with straw or a matchbox taped to a cane. Paraffin put in the hollow ends of canes can also be effective against earwigs.