Using a knife, carefully cut three openings in the top of the growing bag and cut drainage holes in the base. If using bottomless pots (buy ready-made, or make your own), insert them into the openings and fill with soil.
When the plants are hardened off and the first flowers are about to open, plant into the bag or the pots so that the top of the root ball is just below the soil surface. Firm the soil around the roots and water well.
Add canes or strong wires for support. Take care to pinch out all fast-growing sideshoots between the leaves and stem — they divert valuable energy away from fruit production. Apply a liquid tomato fertilizer weekly.
Tie in the main stems with twine as they grow. Stop the plant from growing taller by removing the growing tip, two leaves beyond the fifth or sixth cluster (truss) of fruit. This diverts the plant’s energy into the last fruits of the season.