Helianthus annuus Russian Giant Seeds - sunflower seeds Ref: TM01402956 SowingSow early spring to early summer outdoors where they are to flower. Prepare the ground well and rake to a fine tilth before sowing. Sow 12mm (½in) deep in rows 45cm (18in) apart.<p>For really giant sunflowers, sow them indoors in late winter/early spring, individually in 7.5cm (3in) pots at a temperature of 15-18C (60-65F). Grow on in good light conditions, harden off and plant out when all risk of frost has passed.GrowingThey prefer a sunny open site but will grow in most sites and soils.Aftercare FloweringSummercroppingPlant typeHardy Annual Price: £1.49 Quantity: