Tips for Healthy Dahlias in Devon Gardens
Choosing the right site
We always try to place dahlias in a sunny spot with at least six hours of sun each day. They prefer free-draining soil with plenty of organic matter. If your soil is heavy clay or stays cold, we can build raised beds to improve drainage and warmth. Avoid planting where water pools in wet weather. Good air movement helps reduce fungal problems, but protect plants from the coldest winds which can rip stems and flowers.
Planting and early care
Plant tubers after the last frost when the soil warms in spring. I plant with the eye or shoot facing up and cover with about 10cm of soil. If using potted plants, set them at the same depth as in the pot. Mix some well-rotted compost into the planting hole to give tubers a nutritional boost. Space varieties according to their mature width so air circulates and flowers have room to show.
Feeding and deadheading
Dahlias are hungry plants and appreciate regular feeding through the growing season. Start with a balanced feed once shoots are established and continue every few weeks during bloom. I avoid high nitrogen feeds late in the season because they encourage leafy growth over flowers. Remove spent flowers regularly by deadheading. This keeps plants tidy and extends the display.
Watering and staking
Keep soil consistently moist, especially as flower buds form. Deep, infrequent watering encourages stronger roots. Avoid wetting the foliage to reduce disease risk. Taller varieties need support early, so we tie stems to canes and adjust ties as plants grow. Secure staking prevents damage in summer storms and helps produce straighter stems for cutting.
Pests and disease management
We watch for slugs on young shoots and use physical barriers and biological slug control where needed. Earwigs enjoy hollowed flower heads, so check for them when cutting blooms. Powdery mildew can appear in dry spells with cool nights. Good spacing and removing affected leaves keeps this in check. For vine weevil, inspect pots and containers and lift plants if growth seems stunted so you can check the roots.
Overwintering tubers
In most of Devon the safest approach for tender varieties is to lift tubers after the first hard frost, let them dry, and store them in a frost-free place in slightly damp compost or peat-free medium. Label varieties carefully. Hardy varieties in well-drained borders may stay in the ground if you mulch well and the spot never waterlogs.
We enjoy helping gardeners gain confidence with dahlias, from planning to pruning and seasonal maintenance. Contact our team for advice.
