Plum Tomatoes Growing Guide

Last Updated March 12, 2021 By Bella Zinti

Plum tomatoes are oval-shaped tomatoes and have thicker flesh, low water content, fewer seeds, and less pulp than your traditional tomatoes. This is why many people use them for tomato sauce, stews, canned goods, salad, and much more! While there are many different varieties of plum tomatoes, Roma tomatoes and San Marzano are the two most popular. The smallest plum tomato varieties are about cherry tomatoes' size and are aptly called - grape tomatoes. 

What is A Plum Tomato?

Plum tomatoes are also known as the 'sauce tomatoes' because they are specifically grown for making tomato sauce, puree, or tomato paste. It is an essential ingredient in Italian cuisine.

Plum tomato is super easy to grow right in your backyard with a little care. Here is everything you need to know about how to grow plum tomatoes. 

Plum Tomatoes Growing Guide

Plum Tomato Growth Characteristics

Plum tomatoes grow in upright, bushy plants with deep green leaves. The leaves, stems, and stalk are slightly textured, almost grippy! Small yellow flowers typically bloom in groups and fade into green tomatoes that gradually turn red. Depending on what variety of plum tomatoes you buy, the tomatoes might be orange or yellow instead. Plum tomatoes get very tall and absolutely need caging for support. Otherwise, the plant will fall over on itself, with a high chance of snapping the main stalk and killing the plant. 

Light Requirement

All tomatoes need as much bright sun as you can possibly give them, at least 8 hours of direct sun daily. They are originally grown in tropical regions, and of every typical garden vegetable, they need the most light. 

Soil Requirement

The soil needs to be well-drained and high in organic matter. Loamy soil and even fertile clay produce the most tomatoes, but lighter soils that both drain and warm quickly will produce plum tomatoes quicker. Plum tomatoes can handle slightly acidic soil, doing well in soils with pHs between 6.0 and 6.8.

Water Requirement

Plum tomatoes are sensitive to moisture. If you overwater them or water them unevenly, you'll see immediate unfavorable results. You'll want to water the base of the plant, and carefully! If you splash soil up onto the leaves while watering, pathogens from the soil can cause disease in the plant. You may like to mulch around your tomato plants to decrease the likelihood of that happening. Blossom end rot will occur if the soil is not kept evenly moist. Cracks in the tomatoes occur when the fruit tries to absorb too much water too quickly from heavy rain or heavy watering following dry conditions. 


The highest yield of plum tomatoes will result from a well-fertilized soil high in organic matter. However, they take a lot of nutrients from the soil, and you'll need to fertilize them throughout their growing cycle to get good results. You should avoid fertilizers high in nitrogen, or using fresh manure as compost, as both of them will cause your tomato plant to spend more energy on leaf and stem growth than in developing tomatoes.

Temperature and Humidity

Plum tomatoes, unlike most people, thrive in heat and humidity! Dry heat, however, will cause low production of fruit. Tomatoes must be watered regularly from the plant's base, and be very cautious of planting them outside when the nights are still chilly!

Common Pests

Tomatoes are common targets to a wide variety of pests.

  • Aphids and whiteflies are some of the most common pests. Aphids are tiny insects, some with wings and some without, often found on the underside of leaves in clusters. Whiteflies are bright white, winged insects that form colonies under leaves and fly off en masse when disturbed. Both suck sap from the plant, stunting its growth. First, spray off as many of the pests as possible with water, and then spray the plant with soapy water or horticultural oil to keep them from returning. If they keep popping up, ladybugs are a fantastic natural predator of aphids. 
  • Hornworms are huge, fleshy, green caterpillars that will eat whole leaves and tomatoes from the plant. Cutworms are another caterpillar pest, tending to eat young tomato plants at night. If you see the eggs or caterpillars, remove them. Feed them to your chickens. They'll love them. 
  • Slugs and snails will leave large holes in the leaves and fruit of a plum tomato plant. They prefer moist environments, so a preventative measure is to water directly at the plant's root base, keeping the foliage hot and dry. A sprinkling of salt or diatomaceous earth around the plants will kill them right on the spot.

Growing From Seed

You could buy plum tomato plants as young plants from a greenhouse, but you could also easily start them indoors from seed. Tomatoes have a long growing season, anywhere from 60 to 80+ days, and this head start will get tomatoes on your plate sooner with just a little extra effort. 

Beginning six weeks prior to the final frost date, plant seeds ¼" deep in a seed tray filled with a seed starting mix. Water the seeds until the soil is saturated and then cover the tray to trap the moisture. Germination will occur within a week. 

After the seeds germinate, remove the cover and move the tray to a sunny, south-facing window. Check their moisture daily - drying out will immediately kill the young plants. After two sets of leaves have grown, the seedlings can be transplanted into 4" pots filled with a potting mix. 

When the outdoor temperature is above 55° night and day, put your tomato seedlings outdoors for a few hours each day, increasing the number of hours until they are basically outdoors all day. Then, plant them in your garden, with at least 18-24" between each plant - they get big!

Types Of Plum Tomatoes

Small Plum Tomatoes

Grape tomatoes are small plum tomatoes and got its name because of its size. They are perfect for salad, stir-fry, or enjoy as a sweet snack.

Italian Plum Tomatoes

This variety of plum tomatoes is larger in size and is bright red in color. Italian plum is perfect for making tomato sauce, jam, puree, or add into soup for a fresh tomato flavor.

San Marzano

San Marzano plum tomatoes are long and pointed in shape. They are typically longer than other varieties of plum tomatoes and are perfect for making tomato sauce or canned.

Roma Tomatoes

Roma tomatoes are a special variety of plum tomato families. They are grown through an openly pollinated variety of plants rather than a hybrid. Roma tomatoes boil faster and perfect for canning.

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About the author

Bella has a Bachelors degree in interior design, is a master gardener. She designs nourishing outdoor & indoor spaces guided by the practice of Feng Shui.

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