If you love tomatoes, you’ll love San Marzano tomatoes!
Think of your regular Beefsteak tomato. But then give it two times the flavor for taste.
Thicker skin for easier peeling. With fewer seeds for removal. And less sour vinegary taste, but a more smooth sweeter taste.
That’s San Marzano. It’s an indeterminate tomato (grows all season) that’s pretty rare in the US.
Now, real San Marzano tomatoes come from Italy. They’re highly regulated with quality checks and even a stamp of authenticity.
You may have noticed the “DOP” emblem on certified fruit.
This popular cultivar is so sought after that even fake canned brands started showing up in the US.
It’s not possible to grow the authentic strain here, but we have created our own “US” variant.
While it’s not as juicy or flavorful as the Italian variant, it’s still a different experience compared to other heirlooms you’re used to here in the USA.
Let’s learn about how to grow and care for San Marzano tomato plants so you can grow a small slice of Italy in your backyard!
Guide Contents
Quick care guide: San Marzano tomato
| Plant type | Annual vegetable |
| Origin | San Marzano sul Sarno (Southern Italy) |
| Scientific name | Solanum lycopersicum |
| Other names | San Marzano sauce tomatoes |
| Soil type | Fertile, loamy, well-draining, nutrient-dense |
| Soil pH | 6.0-7.0 (slightly acidic) |
| Sunlight requirement | Full sun, 8 hours daily |
| Bloom season | Summer |
| Colors | Green, white, yellow, red, orange |
| Max height | 8 feet |
| Max width | 3 feet |
| Low temperature tolerance | 50F |
| High temperature tolerance | 95F |
| Ideal temperature range | 70-75F |
| Humidity | Moderate (40% or higher) |
| Watering requirements | 2-3 inches per week, 3 times per week, no soggy soil or drying out |
| Fertilizer requirements | High, use full dosage in spring/summer |
| Plant food NPK | 10-10-10 or 5-10-10 |
| Days until germination | 1-2 weeks |
| Days until harvest | 70-90 days |
| Bloom time | 50-60 days |
| Speed of growth | Moderate |
| Hardiness zones | 5, 6 ,7, 8, 9, 10 |
| Plant depth | 0.25 inches for seeds, plant same depth as original container if from seedling |
| Plant spacing | 30-48 inches |
| Plant with | Sweet basil, allium, celery, parsley, chives, borage, carrots, marigold, nasturtiums, or asparagus |
| Don't plant with | Similar plants in the same family (Nightshade), beans, Brassicas, eggplants, peppers, potatoes, fennel, or kohlrabi |
| Propagation method | From seed or seedlings |
| Common pests | Roly polys, hornorms, tomato fruitworms, flea beetles, tobacco worms, cabbage loopers, whiteflies, spider mites, rodents, birds, aphids, or flies. |
| Common diseases | Leaf spot, blossom end rot, or root rot. |
| Indoor plant | Yes, but only temporarily for weather conditions or hardening off (acclimating) |
| Outdoor plant | Yes |
| Grown in container | Yes |
| Flowering plant | Yes |
| Beginner friendly | Yes |
| Care level | Low (very easy for beginners) |
| Best uses | Sauces, canning, salads, soups, pasta, seafood, Italian cuisines, cherry or beefsteak tomato substitutes |
Toxicity warning
Note that while these tomatoes are delicious, the plant itself is considered to be toxic.
Wear protective equipment when working with this plant. Wash the fruit thoroughly before consumption.
The fruit is edible, but the plant isn’t. It may cause adverse reactions to some individuals or pets.
What’s a San Marzano tomato?
San Marzano is native to Mount Vesuvius, but we can get a taste of those delicious, juicy tomatoes here in the United States.
Native to Italy, their oblong shape and pointy ends give them that unique look. Strong in flavor with a sweet taste, they’re a favorite snacking tomato in the community.
Sometimes referred to as “San Marzano sauce tomatoes,” they have very few seeds and less sour taste.
Even though these tomatoes grow natively in those Italian commercial crop fields, it’s not too hard to replicate the same growing conditions here in the US. But you won’t grow the same strain.
San Marzano tomatoes are elongated tomatoes with extremely fleshy interiors. They’re juicy, moist, and packed full of flavor compared to our Beefsteak or Cherry tomato varieties.
They also have very few seeds per fruit, are easier to peel, and have a unique flavor from their volcanic soil. They’re truly incomparable to domestic tomato strains.
You may see them sold in cans as plum tomatoes or paste tomatoes. They’re about 3” in length and not uniformly shaped. They have blunt ends but may be pointed as well.
The fruits grow in small groups of 6-8 fruits per plant, which make the plant lean because they get heavy. Marzano tomatoes are bright red with weights on average of 5 ounces.
The time to harvest is around 80 days on average but can vary depending on your climate. They’re commonly used for canning or making sauce.
Why do San Marzano tomatoes taste so darn good?
They’re highly regulated in the fields of Italy. Authentic fruits are produced in a tight circle with quality control standards that are much stricter than ours.
The origin is verified with regular QC testing of fruit. They even put a stamp on the fruit to show it off. How’s that for QC?
But here in the US, it’s not the same. When you try to grow it, it just won’t be fruit because of the different soil types. Humidity, temperature, and seasonality make a difference too.
The volcanic soil is what infuses the fruit to give them that distinct flavor. And their distinct price point.
It’s every gardener’s dream to be able to tend San Marzano tomatoes in their garden. But if you’re up for growing the good old USA version of Marzano tomatoes, this guide should give you insight into what’s required for their care.
While the tomatoes won’t have the same taste or texture, they can still give you the taste of Italy you’ve been craving. At least the most you’re gonna get here in the US!
You can still use it for making sauce, canning, drying, creating pastes, or cooking your favorite pasta dishes.
They’re still unique in their own way. Plus, you can pair them with regular tomatoes in your yard like Beefsteak, Cherry, Roma, Early Girl, Black Krim, Celebrity, Campari, Cherokee, or Gardener’s Delight.
Types of San Marzano
There are multiple strains you can find in seed or seedling form.
Here are some of the most popular ones that gardeners love:
- Heirloom San Marzano (traditional elongated shape, thick skin, few seeds, tasty). Sometimes called San Marzano 2 or 3.
- San Marzano Nano (smaller plant, good for pots, determinate, compact, short, cylindrical fruit)
- Golden San Marzano (3 feet tall with plum tomatoes, yellow fruits)
- Pink San Marzano (sweet pink, lots of fruit, pink-colored)
- San Marzano Scatalone (late summer fruit, pear shaped)
How to propagate San Marzano plants
This section covers what you need to do to get your San Marzano tomato plants started. It’s important to note that you should only be growing it in the right hardiness zone.
These tomatoes have been reintroduced to the US as their own strain so that already puts you at a loss since they’re not native here.
If you want to maximize tomato production, you should pay careful attention to the care requirements and provide your plants with what they need.
In other words, there’s little room for error. They are a bit picky.
From seed
The average Marzano plant will produce about 10 pounds of fruit during peak season if properly cared for. This is a good number to shoot for if you want something to aim for.
So if you eat a lot of tomatoes or you plan to use them for all sorts of tasty projects, you should plant them accordingly. It’s always nice to plant extra in case some seeds don’t germinate or the plant doesn’t make it to fruiting.
You can find seeds online, but make sure they’re reputable seed sellers. (Check Amazon for reviews.)
Use rich potting soil for seed sowing. Get a bucket. Clean it then fill it with the soil of your choice. Water it about ⅓ full and stir the water in. it should become moist, but not waterlogged.
The water should quickly drink out of the holes on the bottom. This preps the soil to be used for the starter trays.
Fill each compartment with the soil, leaving about .25 inches from the top. Put 1-2 seeds per compartment, then sprinkle some soil to cover it. Spray each plot with a spray bottle.
It should be moist, but not wet. Cover with a humidity dome or plastic bag. Water regularly and maintain the humidity and water level.
If temperatures drop too cold, use a heating mat under the starter tray.
Put the seeds near a window with full sun where it gets at least 8 hours of daily sun. South-facing windows are ideal. Keep temperatures table between 70-75F with humidity at 100%. Check for bugs or fungus daily.
You should plant enough to get a sizeable amount of tomatoes that go ripe around the same time. But if you want to stagger your harvest, plant in batches each spaced 1-2 weeks apart. This will reduce the possibility of surplus fruit and then going to waste. Think ahead.
Seedlings should be moved to the garden when they’re about 8 inches or taller. When they get two sets of true leaves, it’s ready to be moved into their own pot.
You can use small 5-inch potters temporarily until they’re ready to be moved into your garden. Fill the container ⅔ full with the same soil, then move the seeding into it. Plant the leaves 0.5” below the container edge.
Pack around the seedling. Water generally when the top inch becomes near dry.
If you’re in a zone with warmer winters, you can keep them in the starter kit and then move them outside when there’s no sign of temperature dips.
When to plant
If you’re starting from seed, plant up to 8 weeks inside your house to get the seedlings growing. Only move them outside when the last frost date is over.
If starting from seedlings, wait until early spring when all signs of cold weather are completely over. Put the seedling in a container outside for a few hours each day over a week or two.
This is necessary to get them used to the outside elements. If you just put it outside and leave it there, it’ll likely wither from the cold or the heat. I’m not used to it yet. It needs to adapt. It’s called hardening off.
From seedlings
Buying a seedling plant from your local nursery is the way to go.
While growing from seed is nice, it takes a lot of work and germ rates are low. If you want a head start for the season, or if you’re late, buying a pre-grown plant at a premium is worth it.
Harden them off inside your house before you move them to the outdoors. They should be transplanted when they’re about 12 inches in height.
Give them a bit of sun daily then move them back inside for over a week. Dig a hole twice as wide as the plant, but the same depth as the original. Put ⅔ of the stem into the soil.
Trench growing is ideal for seedlings. Dig a trench and then put the plant sideways with the tip above the soil line. Fill the trench with soil and then water it well. Each plant should be spaced at least 30 inches apart.
How to care for San Marzano tomato
This section covers some general care guidelines to get the most yield out of your Marzano tomatoes.
Note that your care needs will vary depending on the type of local conditions your garden has (soil type, temperature, humidity, etc.).
However, you can use these tips/tricks to get an overall picture of the care level required for growing and caring for these tomatoes.
Hardiness zone
These tomatoes require specific conditions to produce the most fruit.
They like fertile, rich soils with temperate conditions. Extended summers will help maximize their production.
If you’re in USDA zones 5-10, it should be sufficient to satisfy their necessary environmental requirements. Lower zones will struggle with cold dips while higher zones may overheat them.
If it’s too hot or too cold, they both will hinder tomato production.
Soil
San Marzano tomato plants like well-draining, rich, fertile soil.
Use high-quality garden soil, organic if possible. Combine it with topsoil or organic compost.
Organic compost, moss, manure, or leaf litter can be substituted. Garden lime can help bring the pH down so it’s slightly acidic. If it’s too acidic, use wood ash to raise it.
Soil pH
Tomatoes like slightly acidic soil. This particular cultivar requires soil between 5.5-7.0 pH.
Use limestone to naturally bring your pH down if needed. pH won’t make or break your production, but for that juicy flavor, you’ll want to make it acidic. Tomatoes grow well in basic (high pH) soils.
Spacing
When starting from seed, you can put 1-2 seeds per compartment. Don’t worry about spacing them out. They’ll be thinned out when they grow.
When they become seedlings (8 inches +), move them to the garden. Space each San Marzano at least 30 inches apart. This provides ample space for them to extend their roots.
It also minimizes competition for nutrients in the soil column. If you’ve grown nightshades in the same spot prior, don’t plant them there. The soil needs to be reseeded or else there may be no nutrients or possible pest presence.
Never plant nightshade plants in the same spot without practicing crop rotation. This will eliminate bug eggs, replenish the nutrients, and give you more production.
Depth
You’ll need to assess the height of these seedlings if you’re using nursery pre-grown plants. The bottom ⅓ should be fully covered by soil, including the root system.
But the leaves should never touch the soil line. They should be at least 0.5 inches from the surface to prevent rot or pests. If you’re starting from seed, plant each seed 0.25” deep.
Fertilizer
To get those big red tomatoes, you’ll need to use some plant food. Within 14 days of planting outside, find high-quality, organic, 5-10-10 fertilizer.
San Marzano needs low nitrogen so it doesn’t waste its energy on growing leaves, rather than fruit. If you get leggy plants with very few tomatoes, there could be excess nitrogen in the soil.
Fertilizer should be applied as directed with 6 inches of space to avoid leaf burn. Water-soluble plant food works well.
Pruning
When the tomato grows to at least 2 feet tall, start pruning it regularly by using sterilized pruners.
Cut off the suckers so it’ll focus on fruiting. Remove yellow or brown leaves. Cut off failed or spent flowers. Keep it tidy so it’s not too dense with foliage, which may bring in pests.
Prune leaves that are no longer produced or damaged. Don’t prune new leaves unless necessary.
Buds will turn into flowers, which will help pollinate the plant for fruiting. Tomatoes can be hand fertilized if there’s no wind movement, birds, or bees.
Watering
Tomato plants will need their soil to be moist. It should never be completely dried out between watering sessions.
Keep it moist, but not wet or waterlogged. Aim for 2-3 inches of water per week. Adjust as necessary for drought or rainy periods. Use rainwater or compost tea water for ideal tomato production.
Well water or pond water also are good choices.
Sunlight
San Marzano requires full sun like other tomato plants. Provide at least 8 hours of sunlight per day if possible. Don’t plant near other tall plants. They may block the light.
Temperature
San Marzano grows well in temperatures that aren’t too hot, but not too cold either. They prefer temperate conditions with a range between 68-75F.
If temperatures drop to the 60s or above 80F, they’ll stop repining. Ideally, the temperature should be very temperate with long hot summers. That’s what they like.
Soil that’s too cold should be avoided if you’re moving seedlings. The sudden temperature drop can kill the younger plants.
Humidity
Humidity should be pretty moderate with at least 60% humidity in the area.
Temperature between 50-90 degrees should provide the humidity needed if watered correctly. Soil should be moist, but never waterlogged.
Mulching
If your zone is prone to random temperature fluctuations, consider putting a 1-2 inch layer of mulch over the base of the plant. This will help retain soil moisture so you don’t need to water as much.
It also helps insulate the roo