How to Grow Plum Tomatoes

Tomato nomenclature can seem like an overwhelming and confusing subject. Along with heirloom and hybrid tomatoes, there are also indeterminate, determinate, and type classifications for tomatoes. Plum tomatoes are one of the five types, and the other main classifications include globe, cherry, beefsteak, and oxheart. But, what are plum tomatoes and how do you grow them?

A few plum tomato plants can produce a very large harvest, so you should be aware of this when you’re trying to decide how many plants you want.

Defining Plum Tomatoes

The main five tomato types come based mainly on shape and size, and the culinary uses also play in. Plum tomatoes are usually oval in shape and longer from tip to stem than they are wide. Some plum tomatoes are more pear-shaped, and you can also find cylindrical ones.

Plum tomatoes can also have size variations. Mini plum or grape tomatoes are roughly one to two inches long, and the biggest plum varieties top out at five inches or more in length. But, the biggest feature that sets plum tomatoes apart from other types of tomatoes is the amount of liquid pulp you’ll get per tomato.

Due to the more narrow shape, these tomatoes only have two seed chambers or locules. The watery-liquid pulp that surrounds the seeds is a lot lower in plum tomatoes when compared to other types. This makes them great for canning, cooking, and sauce production.

They were bred for centuries as sauce tomatoes, and they offer a rich, deep flavor profile that gets enhanced when you heat them up. The flesh stays very firm, and this includes when the tomato is fully ripe. They’re also much less seedy than other tomato types. Along with use for making sauces, they’re popular in any application where you need a more meaty tomato.

Eight Plum Tomato Varieties to Grow

There are many plum tomato varieties you can get from seed catalogs. When you pick out ones to grow, you should read the description carefully as some will have indeterminate growth and others will have determinate growth.

Determinate and Demi-Determinate Varieties:

• Banana Legs – Banana legs is fun cultivar to grow in garden beds or bigger pots. The plants are very prolific and produces dozens of yellow, brightly-colored, sausage-shaped fruits that get up to four inches long. It has a slightly sweeter flavor profile to it.
• Roma VF – Roma tomatoes are one of the most popular plum cultivars available in home gardens. The VF in the name signifies that these tomatoes are resistant to verticillium and fusarium wilt. These plants top out at roughly four feet tall, and they are very productive. They yield all of their medium-sized fruits in a very short window, and this makes them convenient for canning or sauce making.
• San Marzano – If you plan on making authentic Neapolitan pizza, you need this type of plum tomato in your garden. This is the type of tomato that goes into a traditional pizza sauce. The slender fruits get roughly three inches long with very blunt tips, and they have a full, rich flavor.
• Sunrise Sauce – This newer hybrid paste tomato will produce dozens of plum-shaped, stocky fruits that are a bright gold. The flavor profile is much sweeter than other paste varieties, and the fruits produce in a very short window. This makes it easier to create large batches of sauce, and it works well in small spaces or containers due to the determinate growth habit.

Indeterminate Varieties:

• Amish Paste – Amish Paste is an heirloom variety that produces cylindrical, long fruits that taper to a slight point. It has a very rich, delicious flavor that makes a fantastic sauce. They also work well sliced and put in salads or in salsas.
• Big Mama – As you may have guessed from the name, this is a bigger plum tomato. It’s a bright red fruit that can get up to three inches wide and five inches long. You’ll get a large harvest that is great for soups, canning, or for making tomato sauce.
• Pozzano – This hybrid variety is great for growing in raised garden beds. It has a resistance to fusarium wilt, blossom end rot, verticillium wilt, and tomato mosaic virus. It’s a thicker-walled fruit that has the classic paste tomato shape with blunt tips.
• Speckled Roman – The pretty red fruits on this open-pollinated plant are striped and streaked in bright gold. They will get up to five inches long and you’ll get a heavy yield on every plant with tangy, dense tomatoes.

There are many types of plum tomatoes to consider, but some cultivars are much more popular than others, like the Roma tomato.

Growing Plum Tomatoes

Generally speaking, most plum tomatoes are easy to grow. They are some of the smaller types of tomatoes, so they don’t take months and months to grow on a vine. They’re also very resistant to the typical tomato plant diseases and pests. You can also grow them right in the garden soil in the ground or in containers without an issue.

They have an upright, bushy growth habit with very deep green leaves. The stems, leaves, and stalks are lightly textured and almost grippy. Smaller yellow flowers will dot  the plant in groups and fade to green tomatoes that turn red. Depending on the plum tomato variety you picked out, the tomatoes may be yellow or bright orange instead of red. The tomatoes get very tall, and they will need a support system to keep them upright. If you don’t have one, the plant will fall over, snap the main stalk, and kill the plant.

Fertilizer

The highest yield from your plum tomato crop will come from a well-fertilized soil that is rich in organic matter. However, tomatoes pull a huge amount of nutrients from the soil, so you’ll want to fertilize them throughout the growth cycle to get a big crop. You want to avoid fertilizers with higher nitrogen content or using fresh manure in your compost because this will encourage your tomato plants to spend more energy on stem and leaf growth than developing the fruit.

Light

All tomato varieties require as much light as you can give them, and you’ll need to put them in a space that gets a minimum of eight hours of sunlight each day. Tomatoes were originally grown in tropical regions, so for the typical garden setup, they need the most light out of any plants you have.

Soil

The soil has to be high in organic matter and well-drained. Loamy soil and even fertile clay can encourage more fruit production, but lighter soils will warm and drain quickly to produce plum tomatoes faster. They can handle being in slightly acidic soil, and the ideal pH range is between 6.0 and 6.8.

Temperature and Humidity

As this was originally a tropical plant, it shouldn’t surprise you to note that it thrives in humidity and heat. Dry heat will cause low fruit production, so keep this in mind if you live in one of these planting zones. You have to water your tomatoes regularly from the base, and be very careful of putting them outside when the temperature starts to drop as they can’t stand colder weather.

Water

Plum tomatoes are very sensitive to moisture. If you water them unevenly or overwater them, you’ll see negative results within hours. You always want to water at the base of your plants and avoid splashing soil up onto the leaves. This prevents any soil pathogens from spreading up the plant. You may also want to add a layer of mulch around your plum tomatoes to decrease the chances of soil splatter when you water. If you keep the soil unevenly moist, blossom end rot can happen. Cracks in your tomatoes are very common when the plant tries to absorb too much water too quickly following dry conditions or heavy rainfall.

Getting the growing conditions correct with your tomato plants increases your chances of having a full harvest.

Starting Plum Tomato Seeds

Starting your plum tomatoes from seed is an easy task, and it allows you to get a jumpstart on the growing season by starting them inside a few weeks before the last frost of the spring.

To start, get a seed tray and fill it with your chosen seed starting mix. Poke a ¼-inch deep hole into each hole using a pencil. Drop a single tomato seed into each hole and cover it up with a layer of your seed starting mix. Water the seeds until your seed starting mix is saturated, and then put a cover over the tray to hold the moisture in. You should see seedlings start to germinate within a week.

Next, move your seeds to a sunny south-facing window when the seeds start to germinate. When you do, remove the cover from the seed tray so you don’t accidentally burn the seedlings. Check the moisture level every day, and remember that the seeds will die if they dry out. Continue to nurture your tomato seedlings until they have two sets of scalloped-edged leaves.

Once they do, get four-inch pots and fill them with potting mix to transplant your seedlings. Poke one long hole in each pot using a pencil. Stick a fork into the chamber of the seed tray. Gently pull up the fork and hold the seedling at the base to encourage the seedling to come free. Place the freed seedling in the hole in the four-inch pot, burning the entire thing except the leaves. Plant all of your seedlings in this way and continue to water it whenever the soil starts to dry out.

Don’t move your seedlings outdoors until the temperatures reach 55°F during both the day and nighttime. Once it does, prepare the ground to grow your plum tomatoes. To prepare them for planting, start hardening them off by moving them outside for several hours each day as the weather warms. Over the span of two weeks, gradually increase how long they stay outside until they’re outside around the clock and then plant them.

Growing Plum Tomatoes

When you’re ready to plant your seedlings outside, or if you purchased nursery-grown plants, you start the process by preparing a hole for each tomato plant that is wide enough for the length of your tomato plant and several inches deep. Plant them in a full-sun location.

Grasp your tomato plant by the base and gently pull it out of the container, no matter if you’re growing plum tomato starts or seed-grown tomatoes. Dig a hole that is wide and deep enough to accommodate the root ball. If your plant is in a peat pot, you want the entire pot to be under the soil so the peat material won’t wick water away from the plant. Leave 18 to 24 inches between the plants.

If your plant is spindly and tall, you may want to use the trench planting method. To do this, remove everything but the top cluster of leaves and put the tomato start horizontally in the hole. Bury everything but the top third of the plant under two or three inches of soil. Roots will start to develop along the stem’s length, and this makes your plant stronger. Water your plants thoroughly when you get them into the ground. Put a tomato cage around each plant to support it as it grows. Continue watering your plants whenever the soil is dry to the touch until the soil is saturated. Depending on the variety you planted, your plum tomatoes will be ready to harvest in 55 to 80 days.

No matter if you start from seed or get starters from a nursery, it has to be a minimum of 55°F both day and night for them to survive outside.

General Plum Tomato Care

Your tomato plants will grow quickly and become bushy as well as tall. At this stage, you want to be on the lookout for side shoots, and you should gently pinch them off with your fingers. The reason behind this is that the plants will keep producing more and more leaves. You want it to concentrate on the main foliage to get a lot of flowers for more fruit. Generally, it takes 20 to 30 days for the plant to mature.

Removing the Excess Leaves

It’s important that once the flowers are established, you remove most of the leaves from your plants. By doing this, you give the flowers a much higher chance of developing into tomatoes. They will be able to get a lot of sun to help ripen the fruit. To do this, you want to go to each plant and snip off the stems of each leaf using a shart pair of scissors. Make sure you avoid the stems and leaves that support the flowers.

Staking the Tomatoes

Because tomato plants can get tall, most of them need to be supported in one way or another. Most people choose long and thin stakes. You can use flat stakes or garden canes too, and you stake your tomatoes by:

• Put whichever stakes you want to use right into the soil next to your plant.
• Cut a piece of string and gently guide the stakes toward each other.
• Tie the three pieces together at the top to create a wigwam effect.
• Cut a few pieces of string the same length, and starting at the bottom, tie the stems to each support structure.
• As the plants grow and mature, tie them to the stakes.

Along with using stakes to support your plum tomatoes and make sure that the stems don’t snap under the weight of the plant itself, you can consider a few other support methods if stakes don’t appeal to you. These methods include:

• Cages – It’s popular to use tomato cages in the garden, and they work well for tomatoes, eggplants, and peppers. However, you do need sturdier tomato cages to support these vigorous plants. The thinner cages won’t be able to adequately support the fruits. You can buy or build your own tomato cages.

• Trellises – You can use four by eight foot wire panels to make tunnels and trellises in your garden. You can use them to support tomato plants with an eight-foot long section to support six plants. You will need to tie any new growth to the trellis every week during the summer, but the wire makes a very sturdy support for several indeterminate plum tomato cultivars like Big Mama or Amish Paste.

Supporting the Flower Stems

You will see clusters of small yellow flowers starting to form. These are what will eventually turn into your plum tomatoes. Some of the clusters will slowly start to droop under the weight of the new tomatoes on the stem, and you can prevent this by:

• Cut off a small piece of garden string and tie one end onto each stem’s bunch
• Lift it up slightly and tie the other end to the main stem on the plant
• This helps support each bunch and keep them upright so the plant can continue to take advantage of the sunlight exposure
• Use a liquid tomato feed on all of your plants once every week at this point. This will give the plant more energy and produce healthier fruit.

Harvesting Plum Tomatoes

When you pick plum tomatoes at the peak of ripeness, this is a fabulous garden treat. The fruits will be very firm but have a little give to them. Also, they should be the mature color that the seed pack listed. Tomatoes ripen from the inside out, so color and feel are very good indicators of whether your plum tomatoes are ready to go. Ripe tomatoes will also part from the stem using a gentle tug. If you try to harvest the fruit and they’re still firmly attached, they’re not ready to go yet. With this being said, you may want to use garden snips to harvest your fruits. Doing so can prevent you from damaging the whole cluster or from knocking off the green tomatoes.

The fruits from every determinate tomato variety ripen at roughly the same time. Indeterminate varieties will produce a steady tomato crop until the first frost of the season comes around. If you want to make bigger batches of tomato sauce at one time, you should grow determinate cultivars as all of the fruits ripen together. If you want to make smaller batches, pick out indeterminate cultivars.

When you harvest your plum tomatoes, you’ll need a plan in place to use them as you can get dozens of tomatoes from a single plant.

Plum Tomato Care – Tips and Tricks

There are a few tips and tricks you can use to ensure your plum tomatoes are healthy and as productive as they can be each year. These things include:

• Always add a layer of mulch under your plants because if the water splashes soil onto the foliage, soil pathogens can easily end up on the leaves. Wheat straw is an inexpensive and easy to find type of mulch to consider, and you want to avoid hay because it has seeds that can germinate.
• Pick out a support system for your tomatoes that can accommodate a fully mature plant. A thin, flimsy support system will topple under the weight of all of the fruit.
• Start pruning your tomato plants when they are between one and two feet tall. When you see suckers, you can pinch them off when they’re small. Determinate tomato cultivars will require very little pruning other than removing the suckers under the first flower clusters.
• To ensure healthy growth, your tomato plants need a minimum of six hours of direct sunlight each day to produce fruit. For a bigger harvest, increase this to eight hours a day.

Common Pests for Plum Tomatoes

Tomatoes are a target for a broad range of pests. However, plum tomatoes are much more pest-resistant than other varieties, and this is part of the reason why they’re so popular. A few pests to look out for include:

Aphids and Whiteflies

Aphids are very small insects, and they may or may not have wings. You usually find them in clusters on the undersides of the plant leaves. Whiteflies are winged, bright white insects that form colonies under the leaves and fly off en masse if you should disturb them at any point. Both pests suck the sap from the plants to stunt their growth. You want to get rid of them by spraying off as many as you can using water and a hose. Next, spray your plants with soapy water or neem oil to keep them from coming back. If they keep coming back, introducing ladybugs is one way to stop them as they’re a natural predator.

Hornworms and Cutworms

These are fleshy green, huge caterpillars that will eat entire leaves and tomatoes from each plant. Cutworms are another type of caterpillar pest that love to eat young tomato plants during the night. If you see either the caterpillars or the eggs, remove them by hand from the plants.

Slugs and Snails

Finally, slugs and snails will eat big holes in the fruit and leaves of your plum tomatoes. They prefer to be in moist environments, so one preventative measure you have is to water right at the plant’s base while keeping the foliage dry and hot. A sprinkling of diatomaceous earth or salt around the plants will kill the slugs and snails on the spot.

Bottom Line

Plum tomatoes are a great option to add to your in-ground or container vegetable garden, and they’re especially nice for making tomato sauces. We’ve outlined how you plant them, harvest them, support them, and a few varieties to consider. You can take this guide and use it to get a huge crop this fall.