The term "truss tomatoes" is used widely in Europe to describe tomato varieties that grow in clusters. In the United States, these tomato varieties are more commonly known as "cluster tomatoes" or "on-the-vine" tomatoes. They are easily identified in grocery stores or vegetable markets by the fact that they are sold with the tomatoes still attached to the vines. Truss tomatoes are grown in a similar fashion to other tomato varieties, with the biggest difference being how they are harvested.
Test the pH of the soil where you want to plant the tomatoes, using a home soil testing kit. Tomatoes thrive best in acidic soils with a pH of 6.2 to 6.8. To increase the acidity of your soil, spread a 1- to 2-inch layer of sphagnum peat over the garden.
Fertilize the soil with a phosphorus-rich fertilizer, such as 5-10-10 or 5-20-20, a minimum of 14 days before planting. Use a rototiller to a depth of 4 inches to incorporate the sphagnum peat and fertilizer into the soil.
Remove the young tomato plant from it's container. Using a measuring tape, measure the distance from the bottom of the plant's roots to the spot where the plant's stalk emerged from the soil when planted in the pot.
Dig a hole 1 to 2 inches deeper than the measurement you took and place the plant into it. Fill the remaining space in the hole with soil and lightly compact it by pressing down with your hands. Water the plants thoroughly to further set them in the soil.
Water the cluster tomatoes thoroughly and regularly. Allow the top soil to dry to a depth of 1 inch between watering.
Remove suckers regularly. Look for a small vine sprouting between two V-shaped stalks. Remove them by pinching the sucker until it breaks off.
Harvest the cluster tomatoes by cutting the main cluster stem from the plant with sharp scissors or pruning shears. The tomatoes should remain on the vine until they are ready to be eaten.