Set the lobster traps up as soon as you plant the tomatoes. These plants grow quickly and need immediate support and training from the trellis.
Build the trellis according to lobster trap style and tomato cultivar. For small tomatoes like dwarf, container, cherry and Roma tomatoes, use only one lobster trap. For larger red, yellow or orange mid- to late-season cultivars, use two traps per plant. If you're using multiple traps, stack square or rectangular traps on top of each other or set rounded traps end-to-end or side-by-side.
Train the tomatoes up, over and along the wires or boards of the lobster traps. Tie the stems loosely to the wires or boards using cord or twine, and encourage the plants to train themselves. Tie upward on stacked traps and outward on end-to-end traps. Always tie the main stems rather than foliage, blooms or fruit as the latter will break off.