Veg Seed Sowing Plans for May To ensure a continuous harvest throughout the summer rather than a glut successional sowing of salads, radishes, beetroots, carrots, autumn giant leeks and spring onions and peas should continue. Sow basil, particularly alongside tomato seedlings to help draw white fly away plus spinach, rocket and ornamental salad leaves. Globe Artichokes and Swiss Chard for looks as well as food. Pole, French and above all Runner Beans Purple Sprouting Broccoli, Savoy Cabbage, Kale and Calabrese