How to Grow San Marzano Tomatoes (Complete Care Guide)

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!

Quick care guide: San Marzano tomato

Plant typeAnnual vegetable
OriginSan Marzano sul Sarno (Southern Italy)
Scientific nameSolanum lycopersicum

Other namesSan Marzano sauce tomatoes
Soil typeFertile, loamy, well-draining, nutrient-dense
Soil pH6.0-7.0 (slightly acidic)
Sunlight requirementFull sun, 8 hours daily
Bloom seasonSummer
ColorsGreen, white, yellow, red, orange
Max height8 feet
Max width3 feet
Low temperature tolerance50F
High temperature tolerance95F
Ideal temperature range70-75F
HumidityModerate (40% or higher)
Watering requirements2-3 inches per week, 3 times per week, no soggy soil or drying out
Fertilizer requirementsHigh, use full dosage in spring/summer
Plant food NPK10-10-10 or 5-10-10
Days until germination1-2 weeks
Days until harvest70-90 days
Bloom time50-60 days
Speed of growthModerate
Hardiness zones5, 6 ,7, 8, 9, 10
Plant depth0.25 inches for seeds, plant same depth as original container if from seedling
Plant spacing30-48 inches
Plant withSweet basil, allium, celery, parsley, chives, borage, carrots, marigold, nasturtiums, or asparagus
Don't plant withSimilar plants in the same family (Nightshade), beans, Brassicas, eggplants, peppers, potatoes, fennel, or kohlrabi
Propagation methodFrom seed or seedlings
Common pestsRoly polys, hornorms, tomato fruitworms, flea beetles, tobacco worms, cabbage loopers, whiteflies, spider mites, rodents, birds, aphids, or flies.
Common diseasesLeaf spot, blossom end rot, or root rot.
Indoor plantYes, but only temporarily for weather conditions or hardening off (acclimating)
Outdoor plantYes
Grown in containerYes
Flowering plantYes
Beginner friendlyYes
Care levelLow (very easy for beginners)
Best usesSauces, 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

San Marzano tomatoes growing on vine.
Do you know what type of tomatoes these ones are? Look at their shape!

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

San Marzano tomato growing on vine.
These tomatoes are grown inside a greenhouse.

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 roots so they don’t suffer from sudden temperature changes. Use organic mulch if possible.

If your garden is full of weeds, regular mulching may help keep them out.

Compost

You can buy organic compost to help feed your tomato throughout the season or you can even make your own at home. Leaf litter, bark, hay, straw, or plant matter can all be good sources of compost. Ensure that it’s not infested with pests or rot before using it.

Staking

No matter which type of San Marzano you grow, you’ll need to give it some plant support because those tomatoes will weigh it down.

Even the smaller strains of this plant will require some support because of the heavy, dense vines that bear fruit. Each cluster of tomatoes ranges up to 8 fruits, so it’s pretty darn heavy.

You can use traditional stakes, cages, or trellises. Or you can get creative with it like planting next o a fence or something.

Whatever you choose, plant staking for San Marzano tomatoes is necessary.

Harvesting

Similar to most heirloom tomatoes, Marzano will be ready for harvest in about 80-90 days. It varies based on the local conditions of your garden.

If everything is perfect, you should get about 10 pounds of fruit per plant.

Sometimes, people will want to get a headstart on their crop so it doesn’t go into fall, which can ruin your harvest. If you have a shorter growing season, it makes sense to move the seedlings to the garden as early as you can.

Sow indoors 8 weeks before the last frost date in your zone so you can get them outside right when the springtime is here.

For those in the right zone, or with extra long summers, start 6 weeks indoors. It just takes a few weeks to go from perfectly ripe to reduced yield.

San Marzano tomatoes are NOT good for gardens that have short growing seasons. It needs ample time to produce those signature tomatoes.

If your zone is prone to temperature dips, consider growing varieties that have a quicker time to harvest (TTH) such as Subartic, Glacier, or Cherry.

If you’re familiar with paste tomatoes, you already know that they will produce fruit in small 14-21 day batches at a time (also known as determinate production).

San Marzano is indeterminate, which means they will produce fruit over the entire growing season.

To determine when they’re ready, check for ripeness. They should be firm, bright red, and about 3” or longer in size.

If they’re soft, dark red, or about to fall off the plant, you may have missed your window to taste their peak ripeness.

If they’re still green or yellow, they’re not ready to be removed from the vine just yet. Give them more time, but pick before the fall when temperatures dip.

This will ruin the texture. It takes practice, but once you get it going, you’ll be a Marzano tomato picking expert!

They can be turned into sauce right away after you wash them with warm water. No need to do anything fancy.

When the fruit is big and a bit green or yellow, you can start picking. They’ll ripen after they’ve been picked from the vine. Twist the stem or use pruners to remove it. Don’t pull on it.

Tomatoes will continue to ripen if picked early. So it’s good to pick early rather than later. Keep that in mind when you’re unsure.

Storage

You should use your tomatoes right upon harvesting. San Marzano tomatoes will stay fresh at room temperature for up to 5 days.

Hotter weather or cooler weather will ruin the flavor of it. Unlike beefsteak or cherry tomatoes, these tomatoes do NOT store well in the fridge. It’ll ruin the texture of it.

Growing San Marzano in containers

Container growing is simple.

While the tomatoes are pretty big, they can still tolerate cramped spaces like potters or planters. One 5-gallon pot can hold a single Marzano plant.

For maximal yield, don’t plant more than one tomato plant per container.

Potted plants do have their own set of unique care guidelines:

  • Grow indeterminate varieties
  • Start with 5 gallons then upgraded to 10 gallons
  • Ample drainage is critical
  • Potted tomatoes require more watering compared to soil sown plants
  • Avoid over-fertilizing as this can lead to a nutrient buildup
  • Roots will hit the edge of the pot or grow out of the drainage holes- it’ll need to be upgraded
  • Potted plants offer the portability of moving them around to optimal locations
  • They’ll need staking or caging for support or you can put them near a fence or trellis

Otherwise, care is pretty much the same as soil planted in San Marzano plants. Note that container-grown tomato plants will generally produce less fruit with smaller size vs. soil planted ones.

How to grow San Marzano tomatoes indoors

San Marzano tomatoes will grow to their maximum size only in full sun. Outdoors. If you must take your plants inside, there are a few things you need to keep in mind.

First, you should only take it indoors if you must. Things like cold weather, extreme heat, rain, or drought could require you to bring it indoors temporarily so you can protect it. But once it’s over, take it back outside so it can get the full sun it needs.

The only times your tomato plant should be indoors is because of unfavorable conditions outside OR you’re hardening it off. Seedlings need to be acclimated to the elements before you take them outside for good.

It’s not possible to get the same yield growing indoors vs. outside. Unless you have high-quality lighting systems installed, it’s not going to prosper like in the sunlight.

Companion plants

Plant your San Marzano next to sweet basil, allium, celery, parsley, chives, borage, carrots, marigold, nasturtiums, or asparagus. These are excellent companion plants that pair well with Marzano tomatoes.

Don’t plant with

Similar to other nightshade (Solanaceae) plants, you should avoid planting San Marzano tomatoes with eggplants, peppers, or potatoes. Avoid planting with anything that’s in the same family. If using the same soil plot, be sure to rotate crops or else risk pests!

Pests

San Marzano tomatoes are resilient to many common bugs that may infect other tomato plants.

Some bugs include pill bugs, hornworms, tomato fruitworms, flea beetles, tobacco worms, cabbage loopers, whiteflies, spider mites, rodents, birds, aphids, or flies.

The majority can be controlled by using organic insecticide or horticultural oils for that specific pest. Be sure it’s safe for use on fruits/veggies.

Use as directed.

If bugs are a common issue, consider planting plants like marigolds or other bug-repelling plants nearby. These can help keep pests out of your garden.

Diseases

Tomatoes are vulnerable to leaf spot, blossom end rot, or root rot. These are usually caused by overwatering, poor drainage, or bacterial infections.

Consider pruning more regularly, watering less, or supplementing with calcium (Ca) to the soil column by using soil amendments or by adding some crushed eggshells to it.

Uses

These tomatoes are excellent for making sauces or canning. Or eaten as a delicious snack. They can be substituted for cherry or beefsteak tomatoes in salads, soups, seafood, pasta, or any other meal that need a sweet taste.

Commonly asked questions about tomato care

San Marzano tomatoes grown in the garden.
San Marzano tomatoes. Grown at home.

This section covers questions that readers ask about San Marzano tomatoes.

You may find them helpful for specific tomato plant care. If you have your questions, please post them in the comments section and let us know.

Growing san Marzano tomatoes in Florida

It’s possible to grow San Marzano tomatoes if you’re in the northeastern part of Florida. The soil must be fertile, so amended soils with cow manure are perfect.

The humidity, temperature, and overall weather patterns of this region make it suitable for planting.

Are San Marzano tomatoes hard to grow?

Not really, but they do need some specific care (TLC). They’re not fruits that you can just plant anywhere to which it’ll magically grow.

These tomatoes will need specific temperatures, lots of sunlight, plant food, pruning, staking, compost, and some water.

It sounds like a lot of work, and it can be, but the moment you bite into that fresh Marzano tomato is when you’ll realize you’ll do it all over again.

Plus, once you get the hang of it, it’s easy street. There are hardly any problems growing San Marzano tomatoes that make it different compared to other cultivars. It just needs a bit more care in the temperature range.

Can San Marzano tomatoes be grown anywhere?

No, these tomatoes require fertile soil with a narrow temperature range. If it’s too hot or cold, it won’t fruit. Thus, you should only grow them in the right hardiness zone.

Why are my San Marzano tomatoes not turning red?

They may not be changing from their yellow/green to bright red because of the local temperature. Tomatoes need stable temps that aren’t too hot.

If temperatures exceed 85F consistently, they’ll stop turning ripe and just stay green. Ripening will halt because lycopene and carotene (the pigment that makes them red) can’t be produced by the plant under extremes heat.

Do you pinch out San Marzano tomatoes?

Pinch out the tomato plant’s shoots if you want to focus energy on growing the primary stem. There’s no reason to let the suckers go off because it’ll just waste energy on them.

Pinch them off with serialized pruners as soon as you notice them.

Here’s a video that shows you how to do it:

Can you Trellis San Marzano tomatoes? Do they need to be staked?

Yes, and you should. These tomatoes can get heavy on the vine, especially when each tomato cluster can hold several pounds of fruit.

These plants are heavy with thick vines. They’re a vine plant, not a bush plant. They can grow upwards of 7 feet, so give them plenty of room to climb.

The plant will lean, droop, or even fall over if you don’t give it some support. You can use tomato cages, wooden or metal plant supports, fence supports, wall supports, or trellises.

Note that this is not optional. You MUST give it support or risk losing a batch of tomatoes.

Are San Marzano perennial or annual tomatoes?

They’re considered to be annual vegetables under proper care conditions. They fruit consistently. Not in batches. This means they’re indeterminate plants. Pair with determinate tomatoes for variety surplus!

Are San Marzano tomatoes worth it?

That’s subjective.

Do you think it’s worth putting in the effort to monitor temperature, feed, and water your plants weekly?

Are you willing to check the forecast and give it mulch when the temperature dips?

Does the possibility of a heatwave killing your plants affect your outlook for the work involved?

It’s all up to you. But the taste of San Marzano is incomparable.

How close can I plant San Marzano tomatoes?

Space tomato plants at least 30-48 inches apart from each other. This helps maximize the space they have so they can stretch out those roots.

If you plant them too closely together, they’ll compete for nutrients which marks them both smaller overall. The tomato fruit will be less tasty, juicy, or have poor texture. If you have a smaller garden and you want to grow San Marzano, you’ll need to get creative.

Consider container planting. Or just limit the number of plants you have going on at any given time. Less Is more.

Further reading

Grow your own San Marzano

So there you have it. Now you know the basics of how to grow and care for San Marzano tomato plants so you can grow them in your backyard.

These tomato plants are finicky and picky, so they require a specific set of environmental conditions to thrive.

However, if you’re in zones 5-10, why not give them a try? They’re a nice change of scenery from tomatoes to use in your canning or sauces.

If you have questions, post them below! Happy growing!

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