Growing Tomatoes In Raised Beds: Getting Started

Tomatoes are one of the most common plants you’ll find in a backyard garden. They are popular because they’re fairly easy to care for, can be highly productive in the right conditions, and many varieties work well in containers or a raised bed. Indeed, growing tomatoes in raised beds is a great way to grow them in a small space or an accessible garden!

Since there are so many tomato varieties to choose from, have some fun and make themed beds such as a salsa garden, or opt to include tomato companion plants. Among the many joys of gardening is harvesting what you like to eat, so choose a dish and try to produce all the primary materials you need to make it.

Growing tomatoes in raised beds is a bit different than raising them in the ground. You’ll need to change up a few things in your gardening regimen, and you’ll need to make sure your bed is deep enough. But in very little time, you can begin growing tomatoes in your raised bed.

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Quick Care Guide

Basics About Tomatoes

You know the tomato: round, red, and juicy. The tomato, Solanum lycopersicum, has become one of the most-eaten fruits around the world. It’s eaten fresh, cooked, used in sauces, and canned to save for later. You’ll find tomatoes in popular dishes around the world, utilized in amazing ways to create a variety of unique flavor combinations.

The garden tomato comes in many shapes and sizes. The spherical red tomato is the easily identified classic form, but they can take on many shapes, sizes, and colors. Tomato plants can form a rainbow producing fruits that are red, pink, burgundy, orange, yellow, gold, green, purple, black, blue, or variegated. Tomatoes can be near-perfect spheres, long and slender, bite-sized, burger-sized, smooth, or lumpy. There are many types to choose from!

There are no specific varieties that are best for raised bed growing, but all tomato plants do need some specialized care in a raised garden setting. If space is a concern, grow tomatoes in raised beds that tend to be dwarf varieties or that are determinate. If trellised, even a narrow space can allow an indeterminate variety to climb high in the garden.

Throughout history, people avoided the tomato because it was believed to be poisonous. This idea isn’t too far-fetched; Solanum lycopersicum is in the nightshade family, consisting of many poisonous plants. Eating tomato plant leaves in large quantities can cause digestive and nervous system issues, so stick with the fruit!

Planting Tomatoes In A Raised Bed

Planting tomatoes in raised beds is a slightly different experience than if you plant them in the ground. You may find that it’s easier to grow tomatoes in raised beds since they’re more accessible, but you’ll need to keep a watchful eye on the moisture in your garden bed. Let’s consider some of the aspects that make growing tomato plants in raised beds a little different.

When to Plant

Tomato seed germination can be achieved in several different ways. Start seed indoors under a grow light a few weeks before the last frost. This gives you plenty of time to nurture your seedlings before raised bed planting time.

Once you have growing tomatoes at least 4” in height, and nighttime temperatures remain at or above 50 degrees, it’s time to harden your plants off for transplant into the garden. Soil in raised beds tends to warm up faster than in-ground beds do, so this gives you a longer growing season. A cold frame can ensure young plants grow without any damage from the weather.

Where to Plant

A good-quality raised bed guarantees you can put your plants exactly where they should be. Tomatoes require good sun exposure and can benefit from a wind block of some sort. Plan a location where your trellis or tomato cage will work out well without shading other plants unintentionally.

One of the big perks of a raised bed is that you can grow tomatoes virtually anywhere. If all you have is a concrete patio, a raised garden bed may be ideal. Fill with a good quality of soil and grow to your heart’s content! If you’re renting, put a sheet of plastic down first to avoid staining the concrete with the soil.

How to Plant

At the time of planting, a primary goal should be to make sure your tomato supports are in place. This will become crucial as your tomato plant will need that extra support!

Tomato spacing is also important. Tomato plants should have about 18 inches between them so the roots will have plenty of room to sprawl out. In a 4’x4’ raised bed, putting one plant in each corner should allow plenty of space for four plants with plenty of growing space.

Plant tomatoes deep as they form additional roots along the stem. Your raised bed should be at least 12” deep. The more roots form along the stem, the easier it will be for the tomato plants to absorb moisture from the soil in your raised bed.

Care

Tomatoes grow surprisingly well with minimal care. Most of your effort will be put into garden soil prep or other advance planning. Let’s explore ideal conditions to grow tomatoes in!

Sun and Temperature

Tomatoes thrive when they receive 8 hours or more of direct sunlight each day. The ideal temperatures for tomatoes are between 70°F and 85°F. If temperatures exceed over 90°F, a shade cloth will benefit them in the afternoon until it cools down.

Tomatoes grow in USDA zones 3-10 but are sensitive to long periods of time under 60°F. For early season plants, a cold frame may be beneficial until the weather warms up in your garden. Wrap plastic around the exterior of tomato cages to make a short-term cold frame for very young plants to protect them from unexpected frost.

Water and Humidity

Water tomatoes in the early morning as it will allow the tomato plants to dry out if their foliage gets wet, and earlier is better! Use a soaker hose or drip irrigation at root level.

Your raised bed drains faster than an in-ground bed as most use a well-draining soil blend. As a result, you may need to water more frequently. In hot weather, you will definitely need to provide extra moisture so the garden doesn’t dry out. Aim for 1-2 inches of water per week, but let the moisture of your soil be your guide.

A big problem for many raised bed gardeners is cracking. Usually, this is caused by sudden overwatering, as the skin of the fruit can’t grow as fast as the plant’s pumping moisture into it. To avoid this issue, maintain consistent soil moisture in the garden.

Mulch around your plants to prevent weed development, reduce soil moisture evaporation, and regulate soil temperature.

Soil

Another perk of raised beds is that you can optimize your soil. Tomato plants want rich, fertile, and well-draining soil that’s packed with organic matter. Begin with sandy loam and blend in additional organic matter like worm castings, compost, or forest products for moisture retention, or alternately opt for a premade raised bed mix that includes what your plants will need for success. Blending compost into your premade mix can improve it as well.

Tomatoes prefer slightly acidic soil with a pH range between 5.5 and 6.5. Test your soil annually to see what nutrients it’s deficient in and how to amend the soil for the next year. It’s recommended to practice good crop rotation, even in a raised bed garden, as any common tomato fungi that may live in the soil will have time to dissipate. 

Tomatoes don’t perform in poor soil quality. Avoid hard-packed clay or soil that lacks good organic content. Avoid compacted soil as well, as this can reduce root development.

Fertilizing

Fertilize tomatoes in a raised bed in the beginning when you plant them, and later in the season when they set fruit. Select a high nitrogen fertilizer in the beginning, like a 10-5-5, and switch to high phosphorus and potassium later on for fruiting.

Slow-release, organic granular fertilizers are ideal for raised beds. Tomatoes typically need fertilizer regularly throughout the growing season, especially if your soil isn’t rich. Check the manufacturer’s recommendations and modify them to suit your garden and its needs.

Pruning & Training

Pruning your tomato plants is a necessity. In raised beds, your vegetables are closer together than they might be in the ground. As a result, you need to ensure good aeration. Without aeration, diseases such as blight can spread through your plant.

Remove lower leaves as a tomato plant grows. Suckers should generally be removed to reduce the amount of additional pruning required, as well. Keeping an eye out for suckers should be a regular gardening activity, as they’re quick and easy to remove.

Use plant ties to secure your garden plants to their cages or trellises. Spacing these about one to one and a half feet apart will provide support while your plant is loaded with produce. 

Troubleshooting

You’re bound to find problems with your plant, as it’s just part of the tomato growing process. Let’s consider some of the issues you should prepare for to protect your future harvest.

Growing Problems

Both too much and too little watering can become major issues. 

Too much water can lead to issues with fungal root rot or tomato splitting. Too little will cause a reduction in fruit growth and make the plant less healthy and vigorous. During the summer, too little water could also cause serious wilting. 

And finally, wild fluctuations in watering consistency can lead to blossom end rot, as tomatoes need soil moisture to be able to absorb the nutrients in their soil. 

Maintain consistent and regular watering of your vegetables, but only enough to ensure healthy growth. Provide good drainage to allow excess water to flow away. In addition to good drainage, a layer of mulch can reduce soil moisture evaporation.

Temperatures in excess of 90°F can result in tomatoes dropping their flowers. You’ll have less produce overall. Providing shade cloth can help prevent the summer loss of yellow flowers and help with healthy plant growth. Search for something that provides at least 40% shade for best protection of your tomato flowers.

Pests

Aphids, spider mites, and whiteflies suck the sap from plants. Both of these irritating pests can be treated with neem oil or insecticidal soap. For severe infestations, pyrethrin can be used to reduce their numbers. Treating these keeps them away from other vegetables, too!

Tomato hornworms are by far the most damaging pest on tomatoes. However, other larvae such as cutworms and tomato fruitworms can also wreak havoc in your gardening paradise. These can all be treated with Bacillus thuringiensis, also called BT. You can search your plants at night with a black light as hornworms will glow in UV lighting. Once you’ve found them, hand-pick off what you can, and the BT will take care of the rest.

Flea beetles and the Colorado potato beetle will both feed on tomato leaves and can make lots of holes in them, reducing the tomato’s ability to photosynthesize. These both attack other vegetables as well. Some horticultural oils and neem oil can reduce their feeding tendency. Dusting the leaves with diatomaceous earth also helps. Pyrethrin should be used for severe infestation.

Finally, the last pest we’re covering can’t easily be found by a visual search. Root-knot nematodes live in the soil and chew on the roots. Yellowing foliage could be a sign of their presence, but the telltale sign is only visible in the root system where large nodules form as the plant tries to heal itself. Beneficial nematodes will feed on them in their under-soil location, preventing the root-knot nematodes from doing damage.

Diseases

Early blight (Alternaria solani) is a fungal disease that causes leaf yellowing, bullseye spotting, stem lesions, and can damage fruit. Crop rotation, resistant cultivars, and good plant maintenance will prevent this disease. If it appears, an OMRI-rated copper fungicide can be used to treat it.

Late blight (Phytophthora infestans) is caused by a water mold. Most common in cool (70’s or below) and humid conditions without enough space between plants, this blight begins with dark, water-soaked spotting on leaves. Spots rapidly increase in size and a whitish mold can appear along their edges. Good gardening maintenance can prevent the spread of late blight, and copper-based fungicides can be used for treatment. 

Septoria leaf spot (Septoria lycopersici) is a fungus that causes yellowing leaves with small brown spots. It often begins low on the plant due to spores splashing up from the soil, and is most common in conditions favorable for late blight. A bacterial spot caused by Xanthomonas spp. bacteria can also thrive in similar settings. Copper fungicides adequately treat these issues, but again, good maintenance will prevent them.

A number of viruses can be transmitted by pests, including but not limited to mosaic viruses, tomato spotted wilt, and tomato leaf curl. There are no treatments for these viruses. Remove infected plants from that location and destroy them (do not compost). Plant tomatoes that are disease-resistant cultivars.

Frequently Asked Questions

Q: How deep should a raised bed be for tomatoes?

A:12 inches or deeper is ideal. This gives you ample space for deep planting to encourage better root development.

Q: How many tomato plants can I grow in a 4×4 raised bed?

A: You can plant four tomatoes in a 4’x4’ raised bed with one in each corner. Tomatoes should have about 18” of space between them.