Sow 12mm (half-inch) deep, direct in final position. Sow 4 or 5 seeds in clumps, later thinning to the two strongest seedlings. Allow 100cm (3ft) between rows and 40-50cm (16-20in) between clumps. When the young plants have 5 or 6 leaves, pinch out their growing tips to encourage the growth of side shoots. Keep the plants well watered, and prepare the soil well with organic material and a complete fertiliser.