The Ultimate Plum Tomato Growing Guide

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. 

In this blog post, we'll dive into the world of plum tomato cultivation, sharing essential tips, tricks, and insights to help you nurture these red gems from seed to harvest. Whether you're a seasoned gardener looking to expand your crop repertoire or a newbie with a green thumb in the making, you're about to discover the joys of growing your very own plum tomatoes.

What Is A Plum Tomato?

A plum tomato, scientifically known as Solanum lycopersicum var. cerasiforme, is a distinct tomato variety celebrated for its oblong, cylindrical shape and meaty texture. Also called a paste or Roma tomato, it typically boasts fewer seeds and less moisture compared to round tomatoes. Plum tomatoes are known for their rich, sweet, and slightly acidic flavor, making them a culinary favorite for sauces, canning, and cooking. These versatile fruits are a staple in Mediterranean and Italian cuisine, appreciated for their robust taste and ability to maintain thickness and flavor when cooked down. Their distinctive shape and taste make them a beloved choice among gardeners and chefs alike. 

Plum Tomatoes Growing Guide

Growth Characteristics

Plum tomatoes grow in upright, bushy plants with deep green leaves. The leaves, stems, and stalks 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

Plum tomatoes thrive in full sunlight, requiring at least 6 to 8 hours of direct sunlight each day to flourish and produce abundant fruit. Adequate sunlight is crucial for photosynthesis, the process by which the plants convert sunlight into energy and develop their sweet, flavorful tomatoes. Inadequate light can lead to leggy, spindly growth and reduced fruit production. To ensure optimal results, plant plum tomatoes in a sunny spot in your garden or provide supplementary light if you're growing them indoors. A sun-drenched location is the key to a successful and productive plum tomato harvest.

Soil

Plum tomatoes thrive in well-draining, fertile soil with a slightly acidic to neutral pH range of 6.0 to 7.0. The soil should be rich in organic matter to provide essential nutrients and retain moisture without becoming waterlogged. Amending the soil with compost or well-rotted organic matter before planting enhances its structure and fertility, promoting robust growth and fruitful yields. Good drainage is critical to prevent waterlogged roots, which can lead to diseases and stunted growth. When it comes to soil, the ideal blend of nutrients, pH balance, and drainage is the foundation for healthy and productive plum tomato plants in your garden or container.

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. 

Fertilizer

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. 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

Plum tomatoes thrive in warm temperatures, typically requiring a consistent range between 70°F to 85°F (21°C to 29°C) for optimal growth and fruit development. These plants are sensitive to cold temperatures and frost, which can stunt their growth and damage or kill the fruits. To ensure a successful plum tomato harvest, it's essential to plant them after the danger of frost has passed and the soil has warmed up in the spring.

In cooler climates, consider using season-extending techniques like row covers or greenhouses to protect your plants and extend the growing season, allowing these heat-loving tomatoes to thrive.

Pruning

Pruning plum tomatoes is an essential practice to optimize plant health and fruit production. Start by removing the lower leaves that touch the ground to prevent soil-borne diseases. Additionally, prune away the "suckers," the small shoots that emerge in leaf axils, to encourage a single central stem and better air circulation. This helps the plant channel its energy into fruit production rather than excessive foliage. Pinch or trim these suckers regularly, allowing the plant to focus on developing larger, high-quality tomatoes. Pruning also aids in light penetration, reducing the risk of fungal diseases. Overall, proper pruning is key to a robust and productive plum tomato plant.

Common Problems With Plum Tomato

Tomatoes are common targets to a wide variety of pests.

Aphids and whiteflies 

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 

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 

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.

Fungal Diseases

Plum tomatoes are susceptible to various fungal diseases like early blight, late blight, and powdery mildew. These diseases often result in leaf spots, fruit rot, and overall plant decline. To combat fungal issues, follow proper spacing practices to enhance air circulation around the plants. Consider applying fungicides labeled for tomatoes when necessary, and practice crop rotation to reduce disease pressure.

Cracking

Fruits can develop cracks or splits when they absorb excess moisture too rapidly, often due to inconsistent or overwatering practices. To prevent cracking, maintain even soil moisture by providing consistent and adequate watering. Mulching around the plants can also help retain soil moisture and reduce fluctuations.

Sunscald

Sunscald occurs when tomato fruits are exposed to intense sunlight, leading to pale, leathery patches on the skin. To shield your tomatoes from sunscald, consider providing some shade during the hottest part of the day, especially in regions with scorching summers. Row covers or shade cloth can effectively protect your fruit.

Blossom End Rot

This frustrating problem manifests as dark, sunken spots on the bottom end of the tomato fruit. It occurs due to a calcium deficiency in the plant or irregular watering. To prevent blossom end rot, maintain consistent soil moisture by watering evenly and deeply. Additionally, ensure that the soil has sufficient calcium levels. You can amend the soil with crushed eggshells or apply calcium-containing supplements as needed.

How to Grow Plum Tomato 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 their name because of their 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 are perfect for canning.

Are Plum Tomatoes Pet Friendly

Plum tomatoes are generally safe for pets like dogs and cats when consumed in moderation, but they are not an ideal treat. The fruit itself is non-toxic, but its skin and seeds can be tougher to digest and may cause mild digestive upset if ingested in excess. It's essential to ensure that your pets don't overindulge in tomatoes.

Some pets may also have sensitivities or allergies to tomatoes, so it's best to introduce them cautiously. Additionally, avoid feeding your pets any green parts of the tomato plant, as these contain alkaloids that can be harmful. Always consult your veterinarian for guidance on pet diets.

How To Store Freshly Picked Plum Tomatoes

If your plum tomatoes are not fully ripe, leave them at room temperature. Place them in a single layer on a countertop, away from direct sunlight, and allow them to ripen gradually. Check them daily to monitor their ripening progress.

Once your plum tomatoes are ripe, you can extend their shelf life by storing them in the refrigerator. However, this may affect their texture and flavor, so it's best to use this option if you need to prolong their freshness for a few extra days. Keep them in the crisper drawer in a perforated plastic bag to prevent moisture buildup.

If possible, it's generally recommended to store ripe plum tomatoes at room temperature rather than in the refrigerator. Cold temperatures can dull their flavor and alter their texture.

For the best flavor and quality, plan to use your freshly picked plum tomatoes within a few days of ripening. They're at their peak of flavor and freshness during this time. If you have an abundance of plum tomatoes, consider preserving them by canning, making sauces, or drying them for future use.

How To Enjoy Plum Tomatoes

Plum tomatoes, with their rich flavor and versatile nature, can be enjoyed in numerous ways. Here are some delightful ways to savor these delectable fruits:

Fresh and Simple: Enjoy the pure, sweet taste of plum tomatoes by slicing them and drizzling with a touch of extra-virgin olive oil, a sprinkle of salt, and fresh basil leaves. This classic Caprese salad is a refreshing treat.

Sauces and Pastes: Plum tomatoes are ideal for making homemade pasta sauces, salsas, and tomato pastes. Slow-cook them with herbs and spices for a rich and savory sauce.

Bruschetta: Top slices of crusty bread with diced plum tomatoes, garlic, fresh basil, and a drizzle of balsamic vinegar for a delicious bruschetta appetizer.

Tomato Salad: Combine plum tomatoes with other garden-fresh ingredients like cucumbers, red onions, and feta cheese for a delightful tomato salad.

Stuffed Tomatoes: Hollow out plum tomatoes and stuff them with a mixture of breadcrumbs, herbs, and cheese. Bake until tender and golden brown.

Ratatouille: Include plum tomatoes in this classic Provençal dish with eggplant, zucchini, bell peppers, and herbs.

Canning and Preserving: Preserve the harvest by canning or making tomato jams, chutneys, or sun-dried tomatoes for later use.

Grilled or Roasted: Toss plum tomatoes with olive oil, salt, and pepper, then grill or roast them for a smoky, caramelized flavor.

Tomato Soup: Whip up a comforting tomato soup by blending plum tomatoes with onions, garlic, and herbs, and serve it hot with a dollop of cream.

Tomato Sandwich: Layer slices of plum tomatoes with lettuce, bacon, and your favorite condiments for a delicious BLT sandwich.

Tomato Tarts: Create savory tomato tarts with flaky pastry crusts, cheese, and thinly sliced plum tomatoes.

Cocktail Garnish: Use plum tomato wedges as a garnish for Bloody Mary cocktails or other tomato-based drinks.