Dahlias in Lamorna

Place tubers in trays with moist compost, eye-side up, and cover lightly. Keep at 15–20 °C in a bright spot indoors from 6th February - 20th February. Water sparingly until shoots appear.

• Only moisten the compost if it feels dust-dry, overwatering at this stage quickly causes tuber rot. If the tuber arrived soft, dry it for a day before potting.

Once shoots are 5–10 cm tall, pot each tuber into individual containers with multi-purpose compost from 6th March - 13th March. Grow on in a bright, frost-free place.

• Support the tuber from underneath when potting on, not by the shoot. Dahlia shoots are brittle and snap with very little pressure.

Gradually acclimatise plants to outdoor conditions over 10-14 days from 27th March - 3rd April. Place outside during the day and bring in at night, avoiding frost.

Transplant into well-drained, fertile soil in full sun after frosts from 3rd April - 17th April. Space plants 60 apart and water in well. Use fleece if cold nights are forecast.

• Set the tuber so its neck sits 10–15 cm below soil level. This anchors the plant against wind and protects the crown.

Insert stakes at planting to support tall stems. Pinch out the growing tip when plants reach 30–40 cm to encourage bushiness from 17th April - 24th April.

• Tie main stems to the stake every 30 cm using soft garden twine in a figure-of-eight loop. This stops stems rubbing and snaps in strong winds.

Water regularly to keep soil moist, especially in dry spells. Feed every 14 days with a high-potash fertiliser from 24th April to boost flowering. Stop feeding by 21st November.

• Once soil is warm, apply a 5 cm layer of organic mulch like leaf mould or compost, leaving a gap around the stems to prevent collar rot.

Remove spent flowers weekly from 5th June to encourage continuous blooms. Cut back to a leaf joint to promote new buds.

• Spent dahlia flowers have a pointed, cone-shaped seed head behind the petals. New buds are round and firm be careful you don't remove them.

After the first frost blackens foliage, cut stems back and carefully lift tubers from 12th December - 26th December. Dry, label, and store in frost-free conditions in dry compost or sand over winter.

• Lift with a garden fork, not a spade, to avoid spearing tubers. After lifting, dry them upside down for a few days so moisture drains from the hollow stems.