Dahlia Blue Bell

Dahlia ‘Blue Bell’ is a gorgeous choice for adding rich, elegant colour to the late-summer garden. Despite the name, Dahlias don’t flower true blue—‘Blue Bell’ is best described as a deep violet-purple / blue-toned purple, giving a velvety, jewel-like look that pairs beautifully with both hot colours and softer pastels. The blooms are produced in abundance from midsummer right through to the first frosts, making it a brilliant option for long-lasting impact in borders and patio pots.

It’s also a wonderful cut flower—those saturated blooms look stunning in arrangements and last well in a vase. Plant it in a sunny spot, keep it watered and fed through summer, and you’ll have flowers for months.

Planting Instructions

When to Plant:

Plant Dahlia tubers in spring. For the earliest flowers, start tubers in pots indoors from March to April, then plant out once the risk of frost has passed. If planting directly outside, wait until late spring when the soil has warmed.

Where to Plant:
Choose a sunny, sheltered position with fertile, well-drained soil. Dahlias are ideal for mixed borders, cutting gardens and patio containers. They love warmth and perform best in full sun.

How to Plant:

• Depth: Plant tubers about 10–15 cm (4–6 inches) deep, with the old stem (or growing point) facing upwards.
• Spacing: Space plants 45–60 cm (18–24 inches) apart, depending on the final size.
• Soil Prep: Enrich the planting area with well-rotted compost or manure. In heavy soil, improve drainage with grit.

Watering:
Water after planting. Once shoots appear and growth is underway, keep soil evenly moist, especially in dry spells. Avoid waterlogging. Container-grown Dahlias may need watering daily in hot weather.

Aftercare Tips:

• Pinch out the growing tip once plants are around 30 cm tall to encourage bushier growth and more flowers.
• Stake taller stems if needed, especially in exposed borders.
• Deadhead regularly to keep plants flowering until autumn.
• After the first frost blackens the foliage, lift tubers and store dry and frost-free over winter, or protect in the ground with a thick mulch in milder areas.

Top Tip:
For a vase-full of blooms, cut flowers regularly and keep deadheading—Dahlia ‘Blue Bell’ will keep producing new buds all season.

Plant Details

Flowering Period:

July - October (until first frosts)

Height:
30–48" (75–120cm) (approx. depending on variety type and conditions)

Position:
Full sun

Tender Perennial:
Overwinter tubers frost-free in the UK