Plant of the Month: August
The dahlia is Garsons Plant of the Month. Dahlias bring the wow factor to your garden in late summer and through the autumn, when other blooms have faded. They are versatile garden performers for any outdoor space, with varieties in a multitude of vibrant colours, shapes and sizes.
Many dahlias make a bold statement with their strongly coloured flowers. They range from single flower blooms that would suit a cottage style garden, through to the waterlily style of double blooms and ones with large, pom-pom shaped flowers.
Some dahlia varieties are dark-leaved, for greater variety in the borders. Depending on the variety, you can plant them in containers or in your borders as low-growing flowers, right through to tall-growing showy blooms. Taller varieties are best planted at the back of the border where they can have support and won’t overshadow smaller plants.
For your chosen variety, check its eventual height before planting. Taller dahlias need staking to give extra support that helps stop them toppling over from the weight of their flowers, especially in wet weather. Because of their top-heavy blooms, plant them in a sheltered spot for protection against windy conditions.
Dahlias like full sun and can grow in most soil types, but they prefer a fertile, well-drained soil. If your soil is heavy or clay, you can add horticultural grit or sand and compost to lighten it, or plant your dahlias in containers.
Feed them monthly with a liquid fertiliser, beginning a month before they begin to set buds. Use a high nitrogen feed, changing later in the month to high potash, such as a tomato fertiliser.
Dahlias make lovely cut flowers, so grow extra and cut them to bring indoors. They should keep flowering until the first frosts, so you’ll have a lovely long time to enjoy them in all their glory.