Grow it and you'll see why its one of the more popular paste tomatoes. Standard Red Romas. The shorter height of Roma tomato plants means that you can support them with tomato cages instead of stakes or trellises if you wish. It sets it fruits within a 2 week span, making it perfect for cooking and canning. Plant deeply, burying 2/3 of the stem. Once your roma tomato plants are 6-12 inches (15 to 30.5 cm.) high, start staking the roma tomatoes … A Roma tomato plant will grow to a height of 3 to 6 feet (0.9 to 1.8 meters) tall, with a width of 18 inches (46 centimeters). Roma also offers superb disease resistance. Not all varieties are limited to this size, however. Prepare the soil of your tomato bed by adding compost or a slow release fertilizer. (Read the stick tag that comes with the plant for specific spacing recommendations.) Soil requirements: Tomatoes need well-drained, nutrient-rich soil. Roma Tomato Plants produces an abundance of 3-inch, smooth skinned, thick-walled, meaty fruits with fewer seeds. Once you plant your roma tomato plants, water them at least once a week. Roma tomatoes are no different. Planting: Space 18 to 36 inches apart, depending on type. Red Roma tomatoes usually grow to about 4 feet, or 48 inches, tall.