Photo by Goldlocki (CC BY-SA 3.0).

Scientific Name: Solanum lycopersicum

Common Name: Tomato 'San Marzano'

Family: Solanaceae

Origin:

San Marzano is an Italian heirloom paste-type tomato first released to commercial growers in 1926.  It was first bred in the town of San Marzano sul Sarno near Naples in Italy.

Culinary Uses:

San Marzano is one of the best heirloom paste tomatoes with a thinner skin, fewer seeds, lower acidity and a stronger, sweeter flavour than regular roma tomatoes.   San Marzano is a versatile paste tomato that can be eaten raw diced in salads or sliced on sandwiches but really shines when it's canned or made into sauces.  This is one of the few tomato varieties highly regarded enough to be used for making true Neapolitan pizza sauce.  The low water content of this variety also makes it ideal for making sun-dried tomatoes.

Growing Tips:

Plant San Marzano tomatoes in full sun for maximum fruit production and quick ripening.  Growers in warmer climates may prefer to plant tomato plants in light shade to reduce heat stress during the hotter parts of the day.  If your soil is lacking in organic matter place down a layer of compost or well-rotted manure prior to planting.   San Marzano tomatoes were bred to grow in the rich volcanic soils below Mount Vesuvius in Italy, so be sure to provide them with a rich soil high in fertility.  If planting out seedlings be sure to plant them deeply, up to the level of the seed leaves (cotyledons).  Tomatoes have what is known as adventitious roots, any of the hairs along the stem have the potential to form into new roots if buried.  Because of this characteristic, planting seedlings deeply will give them a more extensive root system better able to anchor the plants and extract nutrients and moisture from the surrounding soil.  Top dress with a complete organic fertiliser if growth is slow or at the first sign of any nutrient deficiencies.  San Marzano is an indeterminate climbing heirloom tomato variety so be sure to weave it through a sturdy trellis as it grows to support the weight of the vines and keep any fruit off the ground.  Avoid wetting the leaves when watering to reduce the chance of fungal diseases such as tomato leaf blight.  Prune off any lower leaves and suckers as your tomato vines grow to prevent splash-back of water and fungal spores from the soil onto the leaves when watering.  Mulch around your tomato plants to further reduce the chance of splash-back and retain moisture.  Inconsistent watering during fruit development may cause tomato skins to split.  If insect pollinators are absent fruit set will be poor, however tomato flowers are self-fertile and you can hand-pollinate them by rapidly tapping any open flowers about once a week to cause the pollen in the male anthers to fall onto the central female stigmas.

When to Sow:

In temperate areas of Australia sow San Marzano tomato seeds any time during Spring.  In frost-free, subtropical areas of Australia sow San Marzano tomato seeds from early Autumn to early Spring for best results.  In tropical areas of Australia sow San Marzano tomato seeds during the dry season, from late Autumn to mid Winter is ideal.

How to Sow:

San Marzano tomato seeds should be sown about 6mm deep.  To produce plants with maximum vigour sow a few seeds in each hole and thin to the healthiest seedling after a few weeks of growth.  Sow San Marzano seeds or plant start about 60cm apart to provide room for their root systems to expand and facilitate airflow between plants, which will help to prevent fungal diseases.

Germination Time:

San Marzano tomato seeds are quick to germinate, with most seedlings emerging 7 to 13 days after sowing.

Time to Harvest:

The San Marzano variety takes between 11 and 13 weeks to start producing ripe tomatoes.  San Marzano produces over a longer period than many other paste-type tomatoes.