San Marzano is not just a tomato. It is the reason Italian pasta sauce tastes the way it does.
The fruits are long, pointed, with thick walls and almost no seeds inside. Cut one open and you will notice how little water there is compared to a supermarket tomato. That density is what makes the sauce rich and velvety without hours of reducing.
This is an indeterminate (cordon) variety, which means it grows tall and keeps producing. One healthy plant, well fed and watered, will give you enough tomatoes for dozens of jars.
🌱 Sowing information
Sow indoors February to April, about 0.5cm deep, in small pots or seed trays. Keep warm (18 to 24°C) and moist. Expect germination in 7 to 14 days. Transplant outdoors after the last frost, spacing plants 50 to 60cm apart in a sunny, sheltered spot.
☀️ Light exposure
Full sun essential. San Marzano needs the warmest, most sheltered spot you have. A south facing wall or polytunnel is ideal in Irish conditions.
💧 Water needs
Water regularly and consistently. Irregular watering causes blossom end rot and cracking. Once fruits start forming, feed every two weeks with a tomato fertiliser.
🌡️ Germination temperature and time
18 to 24°C for germination. Seeds emerge in 7 to 14 days. In Ireland, sow indoors from February and do not plant outside until after the last frost (late May in most areas).
📏 Plant spacing and final size
Plants reach up to 180cm tall. Space 50 to 60cm apart. They need staking or a sturdy support. Pinch out side shoots regularly to keep one strong central stem.
🌼 Harvesting notes
Harvest August to September. Pick when fruits are deep red and firm. For the richest sauce, let them ripen fully on the vine.
🍽️ In the kitchen
Passata, pizza sauce, slow roasted with garlic and basil, or halved and dried in the oven. San Marzano is the tomato that Italian grandmothers argue about. For good reason.
📖 Want to know what to cook with your harvest? Our recipe guide “Welly to Belly: Italian Tomatoes, Seed to Sauce” is packed with simple Italian recipes using exactly what you are growing. Get your copy and start cooking with what you grow.
Technical Data
🌱 Sowing depth: 0.5cm
📅 Sow: February to April (indoors). Plant out: late May
☀️ Light: Full sun, sheltered
🌡️ Germination: 7 to 14 days at 18 to 24°C
📏 Height: up to 180cm. Space: 50 to 60cm
🪴 Support: staking required
⏳ Days to harvest: approx. 90 to 100 days from transplant
🧪 Approx. seed quantity: 300 seeds per gram, 1.25g per packet
Heritage variety from Franchi Sementi, est. 1783. Open pollinated, OGM free.
