1. When to Plant
Outdoors: Plant after the last frost, once soil has warmed - typically mid to late spring.
Indoors/Pre-sprouting: Start them 4 - 6 weeks before your last frost in pots indoors to get a jumpstart.
2. What You’ll Need
Dahlia tubers
Compost or potting mix (light, well-draining)
Pots (if pre-sprouting) - around 3 - 5 L per tuber
Sunny garden spot or bright windowsill
Garden fork or hand trowel
Stakes (for taller varieties)
3. Preparing the Tuber
Inspect for rot or mold - trim off any damaged parts.
Ensure each tuber has a “growth eye” or sprouting point (usually near the old stem).
4. Planting Tubers Outdoors
Choose a sunny spot with at least 6 hours of direct sun per day.
Dig a hole about 10 - 15 cm deep.
Place the tuber horizontally, with the eye facing up.
Cover with soil, but don’t water heavily until shoots appear.
Space plants 30 - 45 cm apart, depending on the variety.
Insert a stake at planting time if needed.
5. Pre-Sprouting Indoors (Optional)
Fill a pot with moist compost.
Plant the tuber just under the surface, eye up.
Place in a warm, bright spot (~18 - 21°C).
Water lightly - keep soil just barely moist.
Once shoots are 5 - 10 cm tall, move outdoors (after hardening off).
6. Ongoing Care
Watering: Once growing, water deeply 2 - 3 times a week, depending on weather.
Feeding: Apply a low-nitrogen fertiliser every 2 - 4 weeks once growth is established.
Pinching: When the plant is 20 - 30 cm tall, pinch out the top to encourage branching.
Staking: Support tall or large-flowered varieties to prevent breakage.
7. End of Season - Lifting & Storing
After first frost blackens the foliage, cut stems to 10 - 15 cm.
Carefully lift tubers with a fork.
Let them dry for a few days in a frost-free place.
Store in a cool, dry, dark spot around 4 - 10°C, in boxes with dry compost, sand, or vermiculite.
