Roma tomatoes, often called paste or plum tomatoes, are valued for their dense, meaty texture and low moisture content, making them ideal for sauces, pastes, and canning. They have a characteristic elongated, oval shape and a sweet-acidic flavor when ripe. Most Roma varieties have a determinate growth habit, meaning the plant grows to a fixed, compact height and produces the bulk of its harvest over a short period. Starting these plants from seed grants access to a wider selection of heirloom and hybrid varieties not available as nursery transplants.
Starting Roma Seeds Indoors
Start Roma seeds indoors approximately six to eight weeks before the last anticipated spring frost date. This timing ensures the seedlings are robust enough to transition outside once the weather stabilizes. Use a sterile, fine-textured seed-starting mix rather than garden soil, which can harbor pathogens and is too dense for new roots.
Sow the seeds about one-quarter inch deep in clean trays or small pots, lightly covering them with the damp growing medium. For fast, uniform germination, maintain the soil temperature consistently between 75 and 80 degrees Fahrenheit, often requiring a seedling heat mat. Once the first cotyledon leaves emerge (typically within five to ten days), immediately move the seedlings under a strong light source.
Seedlings require a minimum of 12 to 15 hours of bright light daily to prevent them from stretching and becoming weak, or “leggy.” A dedicated fluorescent or LED grow light fixture placed a few inches above the plants provides the necessary intensity better than a sunny windowsill. Keep the potting mix consistently moist, but never saturated, as overwatering can lead to damping-off disease.
Hardening Off and Transplanting
Before moving plants permanently to the garden, they must undergo “hardening off,” a gradual conditioning process that toughens their tissues against the elements. This process prevents transplant shock and damage by slowly acclimating the seedlings to direct sun, fluctuating temperatures, and wind. Begin hardening off seven to ten days before transplanting, taking the plants outside for just two hours on the first day in a sheltered, shaded location.
Over the following week, progressively increase the duration the plants spend outdoors and the amount of direct sunlight they receive. This slow introduction allows the plant’s cuticle layer to thicken and adjust to the outdoor environment. Final transplanting should only occur once all danger of frost has passed and nighttime air temperatures reliably remain above 50 to 55 degrees Fahrenheit.
The planting site should receive a minimum of six to eight hours of direct sunlight daily and have rich, well-draining soil amended with organic material like compost. When planting, remove the leaves from the lower two-thirds of the stem and bury the plant deeply. If the seedling is tall, lay it on its side in a shallow trench. Tomatoes grow adventitious roots directly from the buried stem, resulting in a stronger root system capable of supporting a heavy fruit load.
Essential Care for Established Plants
Once established, consistent support is mandatory due to the weight of the developing fruit. Although determinate plants do not grow indefinitely, the concentrated crop load requires staking or caging to keep fruit off the ground and improve air circulation. Drive a sturdy stake or set a tomato cage in place immediately after transplanting to avoid damaging the developing root system later.
The watering regimen must be deep and consistent, supplying the plant with approximately one to one and a half inches of water per week. Fluctuations in soil moisture are a primary cause of blossom-end rot, a physiological disorder resulting in dark, sunken spots on the bottom of the fruit. Apply water directly to the base of the plant to soak the soil deeply, avoiding wetting the foliage, which can encourage the spread of fungal diseases like blight.
Roma tomatoes are heavy feeders and benefit from a scheduled fertilization program. Begin with a side-dressing of a balanced fertilizer once the first fruit clusters set. Choose a formula lower in nitrogen and higher in phosphorus and potassium to promote fruit development over excessive leaf growth. Repeat this application every four to six weeks, applying the granular fertilizer a few inches away from the plant stem to prevent root burn.
Maintaining proper air flow is important for disease prevention, achieved by ensuring adequate spacing and removing the small side shoots, known as suckers. Suckers form in the crotches between the main stem and leaf branches. Regularly inspect the leaves for common pests, such as the tomato hornworm, and manually remove them or treat the plants with an appropriate organic control method like Bacillus thuringiensis (Bt).
Harvesting and Storage
Roma tomatoes are typically ready for harvest about 70 to 80 days after transplanting, depending on the variety and local conditions. The fruit is ready to pick when it achieves a uniform, deep red color and feels firm but yields slightly to a gentle squeeze. They should detach easily from the vine with a slight twist, or you can use small clippers to snip the stem just above the calyx.
If frost threatens, or if you wish to hasten ripening, pick the tomatoes at the “color break” stage. These slightly under-ripe tomatoes will continue to mature indoors at room temperature, driven by the natural release of ethylene gas. Store fully ripe Roma tomatoes at room temperature on a counter, away from direct sunlight. Never place them in the refrigerator, as the cold temperature quickly degrades their flavor and texture.