San Marzano Tomato Seeds – Heirloom Non-GMO Indeterminate Paste Tomato

San Marzano Indeterminate Tomato Seeds

Grow one of the classic names in Italian paste tomatoes with San Marzano, Solanum lycopersicum. This heirloom, Non-GMO, open-pollinated variety produces elongated red tomatoes on vigorous indeterminate vines that continue growing and fruiting throughout the warm season.

San Marzano is especially valued as a paste and sauce tomato. The fruit has meaty flesh, thick walls, relatively few seeds, and less juice than many traditional slicing tomatoes, making it an excellent choice for sauces, tomato paste, canning, soups, roasting, and everyday cooking.

Product Highlights

• Traditional San Marzano Italian paste tomato.
• Heirloom, Non-GMO, open-pollinated variety.
• Indeterminate vines provide repeated harvests throughout the season.
• Elongated red plum-type fruit with meaty flesh.
• Approximately 85 days to maturity from transplant.
• Excellent type for sauces, paste, canning, roasting, and cooking.

Plant Profile

• Common Name: San Marzano Tomato
• Botanical Name: Solanum lycopersicum
• Variety: San Marzano
• Tomato Type: Paste / Plum Tomato
• Cultivar Traits: Heirloom, Open-Pollinated
• Life Cycle: Annual
• Growth Habit: Indeterminate
• Fruit Color: Red
• Flavor: Sweet and robust
• Plant Height: Approximately 36–96 inches depending on support, pruning, and growing conditions
• Light: Full sun
• Soil: Fertile, loose, well-drained sandy loam
• Preferred Soil pH: Approximately 6.2–6.8
• Days to Maturity: Approximately 85 days from transplant

Growing Overview

San Marzano is normally started indoors rather than direct sown. Begin seeds approximately 7–9 weeks before the expected last spring frost. Sow about 1/4 inch deep in a moist, well-drained seed-starting mix.

Under favorable conditions, germination commonly takes about 7–10 days at approximately 65–85°F. Once seedlings emerge, provide strong light to encourage compact, sturdy growth.

Harden seedlings gradually before transplanting. Move them permanently outdoors only after frost danger has passed and warm weather has arrived.

Spacing & Support

Space plants approximately 18–36 inches apart. Vigorous indeterminate tomatoes benefit from extra space and airflow.

Install a strong cage, stake, string system, or trellis at planting time. Unlike determinate tomatoes, indeterminate San Marzano vines continue extending and producing flower clusters throughout the season until frost stops growth.

Watering & Feeding

Maintain regular, even moisture throughout growth and fruit development. Avoid repeated cycles of severe drying followed by heavy watering.

Use fertile, well-drained soil. Excessive nitrogen can create lush foliage while delaying flowers and fruit, so follow soil-test recommendations when possible rather than over-fertilizing.

Harvest & Enjoy

San Marzano generally reaches maturity about 85 days after transplanting under suitable conditions. Harvest when the fruit develops a full red color.

Because this is an indeterminate tomato, harvest is spread across the season rather than concentrated into a short period. Pick ripe tomatoes regularly so the plant can continue supporting developing fruit.

The meaty, relatively low-juice fruit makes San Marzano particularly useful for tomato sauce, paste, canning, soups, stews, roasting, and other recipes where concentrated tomato flavor is desired.

What to Expect

True Leaf's current San Marzano Indeterminate listing contains two different fruit-size descriptions, so we do not promise a fixed fruit length or weight. Actual fruit size varies with strain, weather, fertility, pruning, irrigation, fruit load, and growing conditions.

Likewise, mature vine height varies considerably. Indeterminate plants may reach approximately 3–8 feet depending on support, pruning, season length, and growing environment.

About the San Marzano Name

San Marzano is a recognized tomato variety/type that can be grown in home gardens outside Italy. However, the protected designation “Pomodoro San Marzano dell'Agro Sarnese-Nocerino” PDO/DOP applies only to qualifying tomatoes produced and processed according to the official geographic and production specification in Italy.

Frequently Asked Questions

Is this San Marzano determinate or indeterminate?

This listing is specifically for San Marzano Indeterminate. The vines continue growing and producing tomatoes through the season until frost.

How long does San Marzano take to mature?

Expect approximately 85 days from transplant under suitable growing conditions. This maturity figure is counted from transplanting, not from the day the seed is sown.

Does San Marzano need a trellis or cage?

Yes. Indeterminate plants can become tall and heavy with fruit, so sturdy staking, caging, or trellising is strongly recommended.

What is San Marzano best used for?

Its meaty paste-type fruit is especially suited to sauces, tomato paste, canning, roasting, soups, and stews, although ripe fruit can also be eaten fresh.

Can San Marzano grow in a container?

It can be grown in a sufficiently large container, but this indeterminate form becomes much larger than compact determinate tomatoes. Use a large container, strong support, full sun, and consistent moisture.