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Everything You Need to Know
About Growing Dahlias
Known for their showy blooms and diverse range of colours, shapes and sizes.
What We've Included:
When To Plant | How To Plant | Where To Plant | Aftercare | Common Issues | Flowering Time | Inspiration
About Dahlias
Few plants can match the impact and sheer variety of the Dahlia. With blooms ranging from neat pompon flowers to enormous dinner-plate forms, they are always a bold and beautiful addition to any summer display.
And yet, despite their dramatic appearance, Dahlias can be easier to grow than you might expect.
If you’re new to Dahlias, then this guide has everything you need to get started.
When to Plant Dahlias
Dahlias are tender and should not be planted outdoors until all risk of frost has passed.
Start tubers in pots indoors from March to April to give them a strong head start. Plant out only once the soil has warmed in late spring, typically from May onwards, depending on local conditions.
Where to Plant Dahlias
Dahlias perform best in a sunny, sheltered position with fertile, well-draining soil. They need plenty of space to develop strong foliage and abundant flowers.
Compact varieties are well-suited to containers and patios, while taller types are best grown in borders where they can be supported and spaced freely.
How To Plant Dahlias
When planting Dahlias, it’s best to prepare the soil by loosening it and then remove any weeds. You can then rehydrate the tubers by soaking them in room-temperature water for about an hour before planting.
Place the tuber in a hole just large enough to accommodate it, keeping the stem where shoots emerge level with the soil surface. Firm gently and water thoroughly to help settle the plant in. Dahlias are resilient, fast-growing perennials that establish quickly. Once settled, they thrive with minimal fuss, producing bold foliage and stunning summer blooms.
Borders
Ideal for beds, borders and cottage-style plantings:
Step 1: Space tubers at least 60 cm apart to allow room for foliage and flowers.
Step 2: Place the stem where shoots emerge at soil level, then firm gently.
Step 3: Water thoroughly and cover with a light layer of mulch or compost to conserve moisture and add nutrients.
Step 4: Stake taller varieties if needed in exposed areas.
Step 5: Deadhead spent flowers to encourage continuous blooming throughout the season.
Containers
Compact Dahlias are perfect for pots and patio containers:
Step 1: Choose a container with drainage holes and enough space for the tuber to grow.
Step 2: Fill halfway with multi-purpose compost, place the tuber with the stem pointing upward, roots downward, and cover so the stalk sits just below the soil surface.
Step 3: Water thoroughly, allowing excess to drain.
Step 4: Check soil moisture frequently, especially during hot, dry spells.
Step 5: Add slow-release fertiliser if desired to support ongoing growth.
Step 6: Remove faded flowers to encourage long-lasting blooms.
Aftercare
Step 1: Water regularly - Keep the soil consistently moist but not waterlogged. Increase watering during hot, dry periods.
Step 2: Feed your Dahlias - Apply a balanced liquid fertiliser every 2-3 weeks once shoots appear, or use a slow-release fertiliser for ongoing nutrition.
Step 3: Stake and support - Tall varieties benefit from stakes or cages to prevent stems from bending or breaking.
Step 4: Deadhead spent flowers - Remove faded blooms to encourage new flowering and maintain a tidy plant.
Step 5: Monitor for pests and disease - Look out for slugs, snails, aphids and mildew, and treat promptly if needed.
Storage Tips
Step 1: Lift tubers after frost - Once the first frost has blackened the foliage, carefully lift tubers from the ground.
Step 2: Clean and dry - Gently brush off excess soil and allow tubers to dry for a few days in a frost-free, airy space.
Step 3: Prepare for storage - Place tubers in boxes or paper bags with dry compost, peat, or vermiculite.
Step 4: Store in a cool, frost-free environment - Keep at around 5-10°C, avoiding damp areas to prevent rot.
Step 5: Check periodically - Inspect stored tubers throughout winter and remove any showing signs of rot or decay.
Common Issues & How to Solve Them
Dahlias are generally easy to grow, but a few common problems can occur:
Slugs and snails
Young shoots are particularly vulnerable. Protect plants with barriers, pellets, or natural deterrents, especially in spring.
Aphids
These sap-sucking insects can cluster on stems and buds. Remove by hand, spray with water, or use insecticidal soap if needed.
Powdery mildew
This white, dusty coating that can appear on leaves is often caused by dry roots and poor airflow. Water consistently and ensure good spacing between plants.
Floppy stems
Usually caused by wind or lack of support. Stake taller varieties early and plant in a sheltered position.
Poor flowering
Often due to insufficient sunlight or overfeeding with nitrogen-rich fertilisers. Ensure full sun and use a balanced feed.
When Will Dahlias Flower?
Dahlias are known and well-revered for their long flowering season, bringing vibrant colour to the garden for months.
Most varieties begin flowering from mid-summer (July) and continue right through to the first frosts in autumn (October or November).
With regular deadheading and proper care, plants will keep producing blooms continuously, making them one of the most rewarding late-season performers.
Find Some Inspiration For Your Garden
Dahlias are incredibly versatile and can suit both bold and subtle planting styles.
In borders, they pair beautifully with plants like ornamental grasses, Salvias and Rudbeckias, creating a rich, layered summer display. For a cottage garden look, mix them with softer perennials and let them weave naturally through the planting.
If you’re looking to capture a more contemporary feel, try grouping Dahlias in blocks of colour for a striking visual impact, or plant en masse for a dramatic focal point.
In containers, combine compact Dahlias with trailing plants or complementary blooms to create eye-catching patio displays. Their wide colour range makes it easy to match almost any garden palette.
Beyond their beauty, Dahlias also make excellent cut flowers, bringing long-lasting colour indoors.
Ready to Shop for Dahlias?
Browse our full range of Dahlia tubers and discover everything from compact patio varieties to spectacular dinner-plate blooms. Whether you're filling borders, brightening containers, or creating a cutting garden, Dahlias offer colour, variety and impact all summer long.
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Dahlia 'Cafe Au Lait'
From £4.99Shop Now -
Dahlia 'Totally Tangerine'
From £4.99Shop Now -
Dahlia 'Bishop of Auckland'
From £4.99Shop Now -
Dahlia Pompom Mixed
From £9.97Shop Now
