2. Growing from seeds
If you decide to grow your dahlias from seed then you should sow them somewhere between February and April. Fill a pot or seed tray with compost. Firm the surface then gently push the seeds into the compost. Watering is needed to keep the soil moist. Expect seeds to germinate in 7-21 days. In about five weeks, when the plants have two or more sets of leaves it is time to transplant them. Gently transplant the seedlings in 10cm pots of multipurpose compost, firm and and water well. In the middle of May harden off the plants by standing them outdoors during the day and bringing them in at night. Once all risk of frost has passed, plant them in their final positions.