Dahlia: Sowing, planting and harvest calendar
Can dahlias be sown under cover?
Sow your dahlias in spring indoors or in a heated greenhouse, keeping young plants safe from frost. Use clean seed trays or small pots with drainage holes, filled with peat-free seed compost. Space the seeds rather than crowding them and cover lightly according to the packet instructions. Water gently and keep the growing medium moist without soaking it. Choose a suitable warm place and check regularly for emerging seedlings.
Once seedlings appear, provide good light and ventilate if you use a transparent cover. Avoid excessive heat behind a sunny window. When the seedlings are large enough to handle, move them individually into pots, holding a leaf rather than the stem. Preserve the roots and continue growing them in a bright, frost-free place. Check watering as the plants develop.
Before planting in the garden, gradually accustom the plants to outdoor conditions while protecting them from cold nights. Plant out only once the risk of frost has passed, in sunny, well-drained ground. Match spacing to their expected mature size.
Seed-grown dahlias can vary in flower colour and shape. To reproduce a named cultivar faithfully, use cuttings or division. Seedlings can develop tubers that you keep frost-free over winter to grow your favourites again.
How do you sow dahlias outdoors?
How to plant dahlias?
When do dahlias flower?
How to care for this plant
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Remove faded flowers
To encourage further flowering, remove faded flowers with their short stalks without damaging buds. Leave any heads you want to set seed or keep for wildlife.
