There are two reasons to tie tomatoes, and there's a different tie for each one. Train the leader to grow upright with a loose, figure-eight tie. To support burgeoning fruit, loop a long tie above a fruit cluster, and tie it to the stake 6 to 10 inches higher. Loop the tie twice around the stake and tie it tightly so the tomatoes don't pull it down with their weight.
10 Different and Great Garden project Anyone Can Make 6