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How to Grow and Care for San Marzano Tomato Plants

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Zach's writing ranges from matters of gardening, cooking, aquariums, and fish to more niche topics like coin collecting.

San Marzano tomatoes growing in a patio container.

San Marzano tomatoes growing in a patio container.

If you're in the hunt for a high-yielding heirloom tomato plant, then look no further. The San Marzano tomato is here to please! Although the San Marzano that we know today is much different than in the past, this heirloom tomato variety has origins dating back to 18th century Italy. These squat, indeterminate plants grow rather dense and to a height of 5–6 feet. They produce an almost endless supply of oblong-shaped fruit that weigh roughly 4–6 ounces each and contain few seeds. Growing in clusters of six to eight, the medium-sized tomatoes are great for eating fresh or for use in canning. They're perfect for gardeners that are looking to make the most out of a small space or patio.

Once you've cultivated San Marzano tomato plants for yourself, it's easy to see why others have been doing so for hundreds of years. The plants themselves grow to a manageable height and definitely live up to their name as heavy producers. During the 2013 season, I grew one San Marzano as a patio tomato, and the other was planted in-ground at another location. Both tomatoes grew with great vigor and produced loads of delicious fruits. The tomatoes were used for a variety of sauces, soups, and even some canned salsa.

This article will show how you how to grow and care for this spectacular variety of tomato yourself.

This San Marzano tomato plant was grown in a sunken, 5-gallon container with the bottom removed to allow the plant to reach its roots deep into the ground. As a result, it was highly productive throughout the 2013 season.

This San Marzano tomato plant was grown in a sunken, 5-gallon container with the bottom removed to allow the plant to reach its roots deep into the ground. As a result, it was highly productive throughout the 2013 season.

How to Plant San Marzano Tomatoes

Here are just a few tips for starting your own San Marzano tomato plant:

  • Start From Seeds: Though you can purchase young San Marzano plants from garden centers, growing your own from seed has much more to offer! Not only do you get to know the age of your tomato plant, you'll know exactly how and where it was grown. Timing and proper seedling care is important when it comes to maximizing yields. Plant seeds indoors six to eight weeks before the date of the average last spring frost.
  • Large Container: If you plan to grow them in containers, choose the largest one that you can find. Growing with great vigor, these tomato plants have a root system to match. Small containers will only cause the roots to cramp and tomato production to decrease. To reach the maximum tomato production potential, grow these plants in 20-gallon containers.
  • Tomato Cage: Although these plants will not grow as large as other indeterminate varieties, they will still need the support of a tomato cage. Select a cage that is at least 5 feet tall for the best results.
  • Full Sun: Like all other tomato plants, the San Marzano variety will need at least 6–8 hours of daily direct sunlight. While they will grow in slightly less, the yields and fruits themselves will be smaller.
  • Fertile, Well-Draining Soil: These plants are heavy feeders and will require the in-ground gardener to amend existing soil with plenty of compost or aged manure. Container gardeners should select the highest quality potting soil available. In either case, ensure that the soil drains properly. Slow-draining soils can smother tomato roots and cause rot.
These San Marzano tomatoes were grown in a container on a second-story patio.

These San Marzano tomatoes were grown in a container on a second-story patio.

How to Care for San Marzano Tomatoes

Novice gardeners will have no problem growing San Marzano tomatoes. Other than being a bit bushier than most other indeterminate tomato varieties, they will require the same basic care. Here are a few helpful tips you won't want to miss out on:

  • Prune Regularly: As the tomato plant grows throughout the season, there will be many inner branches that become shaded from regular sunlight. The leaves on these branches will slowly yellow and die off. When half of a branch has turned yellow, it can be trimmed off. Keep up on regular pruning of old branches and suckers to maintain proper ventilation.
  • Support the Plant Well: Even with a tall tomato cage, there are bound to be some branches that break free. Any loose branches should be tied up and supported with soft twine.
  • Slow-Release Nutrition: When transplanting San Marzano tomato plants into their final outdoor location, consider adding some slow-release and organic nutrition to their spot in the soil. A small fish carcass or a quarter cup of bone meal buried below the roots of each transplant will provide steady nutrition for a few months. Since both the fish and bone meal are high in phosphorus, they'll really help out with tomato production later in the season.

Note: If you end up transplanting the plant outdoors, its fruit should be ripe within 70–80 days.

San Marzano tomatoes harvested from the patio. These container-grown tomatoes were only a small fraction of the total tomatoes harvested!

San Marzano tomatoes harvested from the patio. These container-grown tomatoes were only a small fraction of the total tomatoes harvested!

Potential Diseases and Their Remedies

With healthy and thriving garden soil, you'll most likely never run into any issues when growing San Marzano tomato plants. If you've had disease or nutrition issues with your soil, however, things can go wrong. Pay attention to the information below if you've ever had issues with the quality of your soil.

  • Soil-Borne Wilts: Open pollinated and heirloom varieties of the San Marzano tomato plant are less likely to be resistant to soil-borne wilts such as Verticillium and Fusarium wilt. If garden soils are known to have these bacterial diseases present, do not plant San Marzano tomatoes. If plants become infected with Verticillium or Fusarium wilts, cut down the infected plant and throw it away. Do not plant in the same area for at least 3–5 years. Some San Marzano hybrids have been bred with a resistance to these bacterial wilts.
  • Blossom End Rot: Like most other large tomato plants, blossom end rot can occur in San Marzano tomatoes. The cause of this browning of the tip of the tomato fruit is often attributed to a lack of available calcium in the soil. As a preventative measure, work plenty of eggshells or bone meal into the soil at the beginning of the season. Watering at regular intervals can also help in aiding against tomatoes already suffering from blossom end rot.

Comments

Emmanuel Adu on August 30, 2020:

No bat I will like to grow them

Sarge on August 05, 2020:

I have these tomatoes. I've noticed they are brown at the end. A lot of green ones. Help

Joe Martin on August 05, 2020:

This is my first time growing a San Marzano tomato. Mine is 6' tall and loaded with fruit.

David L on July 07, 2020:

Yes I have grown them before, they got blight. Haveing a go this year. Got plants from garden centre, quite surprised.

steve on July 01, 2020:

My leaves are curling. But they still look nice and green.

Suggestions? The plant is not thriving like the other varieties that

are around it.

Nancy on June 23, 2020:

Have grown San Marzano tomatoes for several years. If you live in Northern California try to find Blooms nursery San Marzano plants. They are compact high yield plants. Absolutely the best plum variety tomato for marinara sauce!

Marilou grant on January 23, 2019:

Where do you get a 20 gallon containers?

Bob B on February 28, 2018:

My plants were over 12 feet high, with a lot of tomato's.

Thelma Alberts from Germany and Philippines on July 16, 2015:

I think I have not bought and eaten this San Marzano tomato. It looks beautiful. I will have to look for this tomato in our supermarkets. Thanks for sharing this very useful and informative hub. Voted up, useful and beautiful photos.

Rebecca Mealey from Northeastern Georgia, USA on July 16, 2015:

I'll look for the San Marzano's. What a gorgeous hub! And very informative, too.

JR Krishna from India on July 16, 2015:

I think we don't have these San Marzano variety in India. Never seen them before. Your tomato plant with its fruits look georgeous

Voted up and shared :)

Dianna Mendez on April 12, 2014:

I want to grow patio tomatoes and I will have to look for these at the local nursery. Yours looks so good. Thanks for the tips.

sallieannluvslife from Eastern Shore on April 02, 2014:

Great tips! I have my San Marzano tomatoes started, they are about and inch and a half high right about now...I make all my own sauces and these are by far the best tomatoes for sauce....Great hub - voted up and awesome!