San Marzano Determinate Tomato

Start seeds indoors 6 to 8 weeks before your last spring frost date. Keep soil temperature between 70 and 80 degrees Fahrenheit for reliable germination. Transplants are ready when they develop their first true leaves and can be moved to larger containers if starting early.

Transplant seedlings outdoors after your last frost date, once soil has warmed to at least 60 degrees Fahrenheit. Space plants 24 inches apart with rows 36 inches apart. Harden off seedlings by gradually exposing them to outdoor conditions over 7 to 10 days before planting to prevent transplant shock.

Harvest San Marzano tomatoes when they reach full color and feel slightly soft to gentle pressure, typically 80 to 89 days after transplanting. Because this is a determinate variety, fruits ripen in a concentrated window, so plan to harvest multiple times within a week or two for maximum yield. Pick fruits in the morning when they're cool, and leave a short stem attached to extend shelf life. If frost threatens before fruits fully ripen, pick them at the breaker stage (when they first show color) and ripen indoors at room temperature.

Determinate San Marzano tomatoes require minimal pruning compared to their indeterminate cousins. Once the plant sets fruit, remove lower leaves (up to the first flowering branch) to improve air circulation around the base and reduce fungal disease risk. Avoid aggressive pruning, as determinate varieties naturally regulate their growth and you'll only reduce fruit production.