Super Duplex Mixed Sweet William Seeds 6650 Big, extra double flowers in reds, pinks, rose and whites with an old-fashioned charm. Selected by growers for a very high proportion of double to single flowers. Tall 40 cm (16″) plants are crammed with flowers that start appearing in early summer. Suitable for cold-frame sowing in April to early May. Often self-seeds. Needs adequate moisture to germinate. Biennial hardy to Zone 3.
How to Grow
800 seed/gram Seed can be directly sown in the garden in a sunny spot in mid to late May for flowering in the following year. Seed can be started indoors in a soil-less mix 8 weeks before last frost. Sow seed 3 mm (1/8″) deep and keep at 21 C (70 F) for the 10-20 day germination period. After germination, grow on at a slightly cooler temperature before hardening off and transplanting outside to a sunny spot after the danger of frost has passed. Space plants 25 cm (10″) apart in the garden.