SUPPORTING your plants
Apart from the smaller varieties, your dahlia plants will need to be supported to avoid the wind or just the weight of the flowers breaking the brittle stems.
This is usually done by tying the plants to stakes with garden twine.
Stakes can be made of wood – at least 12mm thick – or metal. Normally they will be 1.8 metres tall (supports a plant up to about 1.5 metres after it is driven in) or more. You can start with shorter ones if you want your patch to look more like a garden and less like a commercial nursery and replace them as the plants grow. Shorter stakes may be adequate for some varieties.
Place the stakes first and then plant to avoid the risk of impaling the tubers or roots. Take care to label the stakes with the name of the variety – it is easy to mix them up. You can plant two tubers to each stake although an individual stake makes later grooming of the plant a little easier.
Begin tying when the plant is quite small, 20-40cm, to train it upright and to prevent the wind damaging the feeder roots by rocking the plant – it will grow faster. This tie can be removed later to avoid strangling the plant.
As the season progresses tie your plants to the stakes about every 30cm up – tight around the stake to stop the tie slipping and loose around the plant to prevent damage to the stalk as it thickens.
A less laborious approach if you have a larger plot is to support your dahlia plants in groups.
One option is to construct a trellis by running wires along a row of stakes and tying the plants to the wires rather than the stakes. An alternative is to use horizontal mesh – available in various sizes from horticultural suppliers – supported on each side of the bed which will usually consist of two rows of plants. The mesh can be arranged in two layers or a single layer that is lifted as the plants grow.
In either case extra care is needed to label the varieties or record their positions.