Growing Dahlias
Best Location for Planting Dahlia Tubers
Dahlias thrive in sunshine. Choose a location with at least 4–6 hours of direct sunlight daily.
Avoid waterlogged soil by improving drainage with compost or manure. Space tubers about
50cm apart. Taller varieties may need staking to protect them from wind.
Preparing Soil for Dahlias
Healthy soil is key. Clear weeds and debris, loosen the soil to a depth of 20–30cm, and mix
in compost and dahlia fertiliser. Ensure the soil drains freely to prevent root rot.
When to Plant Dahlias
Plant once the risk of frost has passed. Best months: October–November. Planting up to late
December still gives a summer display.
Dahlia tuber parts
How to Plant Dahlia Tubers
Dahlia tubers have a crown with eye(s) – where the new shoot grows from, a body – the
swollen part that contains sustenance for the plant to grow from, and a neck that connects
these two. Take care not to break the neck as this will prevent the tuber growing. Tubers
come in many shapes and sizes – even an AA battery sized tuber will produce a healthy
plant.Dig a hole 5–10cm deep. Place tuber horizontally with the eye (bud) facing upwards. Cover
with soil and firm gently. Space about 50cm apart and water lightly after planting. Do not
water until shoots appear. Stake at planting time to prevent impaling the tuber later.
If you wish to get the tubers started earlier, you can place in a pot with damp – not wet –
potting mix. Do not water until roots develop – check the bottom of the pot.
Dahlia Care
• Watering: Keep soil evenly moist, not soggy.
• Feeding: Fertilise every 4–6 weeks.
• Pinching – when the plant is about 20-30cm high pinch/cut out the centre stem down to
2/3 sets of leaves. This encourages side branches and more future flower stems.
• Weeding: Keep the area weed-free.
• Support: Stake tall varieties early.
• Deadheading: Remove old blooms to extend flowering.
• Mulching: Apply straw or bark to conserve moisture and suppress weeds.
Common Dahlia Pests and Problems
• Aphids/Earwigs: Remove or Spray with soapy water or natural insecticide.
• Slugs & Snails: These love young dahlia shoots. Use traps or remove at night under
torchlight.
• Powdery Mildew Fungal diseases: Improve airflow by plant spacing and removing lower
leaves. Water in the morning so the leaves dry out before nighttime.
Root Rot: Ensure free-draining soil and avoid overwatering.
How to Pick Dahlias for Cut Flowers
Pick blooms when they are fully open, as dahlias don’t continue opening once cut. Harvest
early in the morning, place in water immediately. Cut low down into the plant for maximum
stem length and encourage future long stems.
