San Marzano Tomato Plants & Diseases

San Marzanos (Solanum esculentum) are somewhat favorite canning tomato variety due to their great-tasting fruit, easy-to-remove skin, few seeds, along with higher proportion of honey. San Marzano tomato crops have traditionally been developed by Mount Vesuvius near Naples, Italy, but this really flavorful tomato is now available to home gardeners in the United States. Learning about its growing requirements, plant care and disease management is the initial step in creating delicious, vitamin-rich fruit.


Paste tomatoes like the San Marzano variety have a dry meaty flesh with small seed cavities. San Marzano tomato crops create deep red, crack-resistant fruit, typically about 3 ounces and 3 to 4 inches long. Initial Italian San Marzano tomatoes are box-shaped with a pointy end, whereas some hybrid varieties produce fruit that is more cylindrical. San Marzano plant height generally ranges between 2 and 4 feet, with green medium-sized leaves and yellow or white flowers.

Growing Requirements

Healthy San Marzano tomatoes require full sun, a minimum of 6 hours of direct constant sunlight a day. San Marzano plants are tolerant of most soil conditions but grow best in moist soil with a pH range between 5.5 and 7. Most tomato varieties grow best in dry hotter climates, however, San Marzano tomato plants also grow well in cool and foggy locations. This tomato cultivar is a indeterminate, or vining tomato variety that may continue to flower and produce fruit during the growing season. The time from planting to harvest these tomatoes is about 78 days. San Marzano plants are open-pollinated, so seeds will create exactly the exact same plant and fruit quality year after year.

Plant Care

Given their vining temperament, San Marzano tomato crops may require some kind of staking or cages, providing support for fruit-laden branches. Moreover, for healthy fruit growth and growth, fertilizer boosts may be required during the growing season. Water-soluble fertilizers provide quick-releasing nutrients and are generally applied biweekly, although individual product directions may vary. Temperature-controlled fertilizers release nutrients more slowly and are generally added to dirt only once throughout the growing season. If utilizing an organic product, such as a fish emulsion fertilizers, implement as instructed on product labels.


San Marzano tomato crops have historically been sensitive to infection, and in the 1970s that they have been nearly wiped out by the cucumber mosaic virus at the Naples area. Today hybrid varieties provide some level of immunity to common diseases like verticillium and fusarium wilt. These fungal wilt diseases are observed in plant debris or dirt and are exacerbated by cool moist weather. Applying too much nitrogen-rich fertilizer can further worsen the issue. Leaf spot is another disease that plagues San Marzano tomato crops. Caused by a fungal or bacterial disease, leaf spot causes brownish or black spots on leaves. Blight could be a devastating disease to San Marzano plants, resulting in rapid deterioration, spotting and wilting of foliage. The San Marzano variety, however, has shown some tolerance to late blight.

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