Welcome to Conerin Farm's comprehensive guide on growing dahlias. These stunning flowers are known for their vibrant colors, bold blooms, and long-lasting presence in your garden. Whether you're a beginner or an experienced gardener, this guide will provide you with everything you need to know to care for your dahlia tubers.

 

Why Grow Dahlias?

 

Dahlias are beloved for their versatility in both garden beds and flower arrangements. With proper care, dahlias can bloom from mid-summer through to the first frost, producing an abundance of flowers that are perfect for cut flowers or garden enjoyment. They're available in a wide range of colors, shapes, and sizes, making them a favourite for gardeners seeking a vibrant display.

 

Planting Dahlias

 

1. Soil Preparation Dahlias thrive in well-draining soil rich in organic matter. Before planting, amend your soil with compost or well-rotted manure to ensure nutrients are available. The ideal pH for dahlias is between 6.0 and 7.0.

Tip: If your soil is heavy clay, consider planting dahlias in raised beds or pots to improve drainage.

2. Planting Depth and Positioning

Timing: Plant your tubers in spring, after the last frost date in your area. The soil should be warm (about 15°C or warmer).

Depth: Plant the tubers about 10-15 cm deep, with the eye (the growing point) facing upwards.

Spacing: Space your tubers 60-90 cm apart to allow for air circulation and growth. For smaller varieties, 30-45 cm spacing may suffice.

Watering: Water well at the time of planting, but be careful not to overwater, as tubers can rot in soggy soil.

Tip: If planting in cooler climates, consider starting the tubers indoors in pots and transplant them after the frost risk has passed.

 

Growing Dahlias

 

1. Supporting Your Dahlias

Many dahlia varieties can grow quite tall, sometimes exceeding 1.5 meters in height. For these taller varieties, it’s essential to provide support to prevent the stems from breaking under the weight of the blooms.

Support Options: Use stakes, bamboo canes, or flower cages. Be sure to stake early in the season to avoid damaging tubers later.

Tip: For a more aesthetic garden, opt for discreet supports like green or natural-colored stakes that blend in with the foliage.

2. Pinching and Pruning

To encourage bushier growth, pinch out the growing tip of the plant when it reaches around 30 cm tall. This will promote lateral branching and result in more flowers.

Deadheading: Regularly remove spent blooms to extend the flowering season and encourage more buds to form. This simple practice can result in a much longer blooming period.

3. Fertilizing Dahlias

Dahlias benefit from regular feeding, but be careful not to overdo it with nitrogen, as this can lead to lots of foliage with fewer blooms.

Recommended Fertilizer: Use a low-nitrogen, balanced fertilizer (e.g., 5-10-10 or 10-20-20) every 4 weeks during the growing season. Stop feeding once the flowers begin to fade toward the end of the season.

Tip: Avoid high-nitrogen fertilizers, as they promote leafy growth rather than flower production.

 

Care Throughout the Growing Season

 

1. Watering

Dahlias prefer consistent moisture, but they do not tolerate soggy soil. Water the plants deeply 2-3 times per week, depending on your soil and weather conditions. In especially hot climates, you may need to water more frequently.

Tip: Use a soaker hose or drip irrigation to avoid wetting the foliage, which can lead to mildew or fungal diseases.

2. Pests and Diseases

Dahlias can be susceptible to common garden pests such as aphids, slugs, snails, and spider mites.

Control: Use insecticidal soap or neem oil for aphids and spider mites. Slugs and snails can be managed with organic slug pellets or beer traps.

Disease Prevention: Ensure good air circulation by spacing plants properly and watering at the base of the plants rather than overhead.

Tip: Regularly inspect your plants for signs of pests or disease, and act promptly to minimize damage.

 

Harvesting and Arranging Dahlias

 

For the longest vase life, cut dahlia flowers early in the morning or late in the evening when the buds are half-open. Use sharp, clean shears to avoid crushing the stems.

Tip: Immediately place the cut flowers in a bucket of cool water. Remove any leaves that will be below the waterline to prevent bacterial growth.

 

End of Season: Winter Care for Dahlias

 

1. Lifting and Storing Tubers

In frost-prone areas, dahlias need to be lifted and stored over winter. After the first frost, cut back the foliage to about 15 cm above the ground. Carefully dig up the tubers, being mindful not to damage them. Shake off excess soil and allow the tubers to dry in a cool, dry location for a few days.

Storing Tubers: Once dry, store the tubers in a well-ventilated container filled with slightly moist sand, sawdust, or vermiculite. Keep them in a cool, dark place (around 4-10°C).

Tip: Check the tubers periodically for signs of rot or dehydration, and adjust storage conditions if necessary.

2. Replanting in Spring

When spring arrives and the risk of frost has passed, replant the tubers in the garden or containers. Follow the same steps for planting and positioning as you did when you first received them.

Tip: Divide crowded tubers before replanting to increase your stock of dahlias!

 

Additional Tips for Growing

 

Mulching: Apply a layer of organic mulch around the base of your plants to conserve moisture, regulate soil temperature, and reduce weed growth.

Companion Planting: Pair dahlias with lower-growing companion plants like marigolds or nasturtiums, which can help attract beneficial insects and deter pests.

Long Blooming Season: Dahlias bloom from mid-summer to the first frost. To extend the flowering season, provide consistent care and protection from harsh weather.

 

Conclusion