Vibrant Dahlias are one of the most widely grown and much loved cut flowers. Their brilliant blooms come in a wide range of colours, flowering from mid summer until the first frosts. Almost every garden is suited to Dahlias whether that is in the border or an attractive container.
Dahlias like full sun and free draining soil, where they will thrive and bloom abundantly, but also grow well in large pots. Dahlias are not hardy and should not be planted until the soil has warmed and all danger of frost has past. They are best started in a heated glasshouse or polytunnel during the spring and are hungry plants that require quality compost or well-rotted manure.
When you plant your Dahlia tubers dig the hole 12-15cm deep and place them horizontally with the growing eye facing up. Then refill the hole with soil. It is important to remember Dahlias get quite large, so allow at least 45cm of space between plants.
These beauties require generous amounts of water throughout the growing season if the summer is warm and dry. When you are just starting to grow them they should only be watered when you see the first green shoots breaking through the ground. Overwatering before shoots are visible can lead to tuber rot. Once the plants reach 30cm tall, give them a pinch by snipping out about 8cm of the growing centre to encourage low basal branching, which increases flower production and overall stem length.
As for pests slugs and snails damage young plants. You may want to put down slug and snail bait at planting time and periodically throughout the season. Nematodes are also an organic option that is safe for both children and pets, and works well. It is important to stake the plants as many will get tall and this will prevent them from falling over.
While Dahlias are not a very long lasting cut flower, you can get 5-7 days from stems picked at the proper stage. Since Dahlias don’t open much after they’ve been harvested, it’s important to pick them almost fully open, but at the same time not overly ripe where they have begun to brown. Check the back of each flower head, looking for firm and lush petals as these make the best cut flowers.