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