San Marzano Tomato

San Marzano Tomato

Solanum lycopersicum

Start san marzano tomato indoors 4 weeks before your last spring frost, then plant out 2 weeks after your last spring frost. Space plants 24 in (61 cm) apart.

Photo: Jonathan Billinger, CC BY-SA 2.0 · source

When to plant

Timed from your frost dates, so it holds wherever you garden. Give yours and every step below becomes a date.

See the dates for your garden

Enter your average last spring frost and first fall frost. Every timing on this site turns into a calendar date. Not sure of yours? Your local extension service or a search for “last frost date” and your town will tell you; the app finds them from your location.

Last spring frost
First fall frost

Saved in this browser only. Nothing is sent anywhere.

Optimal Indoor Start

From seedRecommended
  1. Start indoors4 weeks before your last spring frost
  2. Begin hardening off1 week after your last spring frost
  3. Plant out2 weeks after your last spring frost
  4. First harvestabout 80 days after planting out

Optimal Transplant

From seed
  1. Plant out2 weeks after your last spring frost
  2. First harvestabout 80 days after planting out

Growing san marzano tomato

Spacing in the row
24 in (61 cm)
Between rows
42 in (107 cm)
Planting depth
1/4 inch
Sun
Full Sun
Soil
Well-drained, fertile loam
Germination
5-10 days at 70-85°F
Harvest season
Summer, Fall
Mature height
36-96 inches
Support
Trellis, Stake, Cage
Life cycle
Annual

Sow seeds 1/4 inch deep. Requires warm soil for optimal germination.

Watering. Consistent watering, especially during fruit development; avoid overhead watering to prevent disease.

Neighbours

The companion chart →

Grows well beside

Keep apart from

Feeding

Seedlings
Apply diluted liquid fertilizer after true leaves appear.
Growing
Use a balanced fertilizer every 2-4 weeks or when fruit set begins.
Flowering and fruiting
Switch to a phosphorus/potassium-rich fertilizer once flowering starts.
How often
Every 3 weeks from first fruit set until harvest. Avoid nitrogen before fruit sets; San Marzano is prone to blossom-end rot, so keep watering even and consider calcium nitrate as the side-dress.
Note
Avoid excessive nitrogen after initial growth to prevent over-foliage and reduced fruit set.

Your san marzano tomato, planned to the day.

Canopy turns these timings into dates from your own frost data, places every plant at its spacing on your garden map, and tracks it all the way to harvest.

Add san marzano tomato to your planting calendar →

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