How to Grow Tomatoes in a Raised Garden Bed

Growing tomatoes in a raised bed is a great way to improve your tomato crop with minimal effort.

There are many benefits to growing tomatoes in raised beds, including a longer season and improved soil, all of which will result in healthier, more productive plants.

In this post we will discuss the advantages of growing tomatoes in a raised bed, how to build your own with just a few simple tools, and how to prepare and cultivate your raised bed.

Why Grow Tomatoes in a Raised Bed?

Why Grow Tomatoes in a Raised Bed?

It might seem simpler to just plant your tomatoes directly into the ground, but there are many benefits to growing your tomato crop in a raised bed.

The benefits of growing tomatoes in a raised bed include:

  • Lengthening the season: Soil in a raised bed gets warmer earlier in the season, and stays warmer longer at the end of the season. This extra warmth will extend your season and keep your heat-loving tomato plants happier.
  • Better Soil: You’ll have absolute control over the soil quality and pH, because you won’t be dependent on using the soil already in your yard or garden. 
  • No Till: Since you’ll be filling your raised beds with your soil of choice, there’s no need to till the existing ground. You’ll be starting with a soil mix that’s already loose and aerated, which will make it easier for your plants’ roots to penetrate the soil and create a great root system.
  • Excellent Drainage: Because your raised beds are higher than the ground around them, and filled with wonderfully loose soil, you already have great drainage built into your design.
  • Easy to Add Season Extenders: Your raised bed acts as a base to which you can easily attach a low hoop house or row cover to extend your season even longer.
  • Add Beauty: Raised beds are visually appealing and great for small spaces.

How to Build a Raised Bed

How to Build a Raised Bed

Of course, before you grow you’ll need to build or purchase a raised bed. Premade raised beds or raised bed kits are available, but it’s fairly simple to build your own.

How Big Should My Raised Bed Be For Growing Tomatoes?

How Big Should My Raised Bed Be?

This depends on what space you have available, and your gardening goals. Tomato plants should be spaced 2-3 feet apart, so the size of your raised bed depends in part on how many plants you’d like in each bed.

For example, let’s assume you are growing a cultivar that requires two feet of space between plants.

In this case, a 4 x 4 raised bed would have enough space for 4 plants, if oriented closer to the corners of the bed than the center.

Your raised bed also needs to have plenty of depth. Twelve inches deep is ideal. If you purchase 12” wide lumber, your raised bed build will be simpler, because you will only need one piece of wood per side.

If you have back issues, consider building deeper raised beds that will allow you to weed and harvest with less strain.

A two to three foot high bed will let you work upright while kneeling, depending on your height.

Make sure your raised bed is designed in a way that you can reach all areas of its interior.

A good rule of thumb is that the short sides (or all sides in a square) should be no longer than 4 feet, so that you can easily reach the middle for planting, weeding, and harvesting.

What Material Should I Use to Build My Raised Bed?

You can make a raised bed out of all sorts of materials: cement blocks, hay bales, logs, and stumps.

Creating a raised bed out of these materials is pretty straightforward: arrange them in a square or rectangle, fill with soil, and plant.

Mostly commonly, though, raised beds are made from lumber. This is easy to do with a few simple tools and the most basic carpentry skills.

What Kind of Wood Should I Use For My Raised Bed?

What Kind of Wood Should I Use For My Raised Bed?

You may be wondering if it’s okay to use pressure treated wood to build raised beds. While it’s true that pressure treated wood contains safer chemical compounds than it has in the past, a lot of gardeners are understandably hesitant to use pressure treated wood in the garden.

Up until 2004, pressure treated wood contained chromated copper arsenate (CCA), which was found to be dangerous and is no longer used in residential settings.

Now, most pressure treated wood is treated with alkaline copper quaternary (ACQ), which is thought to be safe but still has the potential to leach into your soil, and therefore into your food, and you.

If you have concerns about using pressure treated wood, the best alternative is a naturally rot resistant wood such as black locust, cedar, or redwood.

A raised bed made out of these materials can last for decades, even when exposed to the elements, but these wood choices can be expensive.

A lower cost alternative is to use a less expensive wood, such as fir or pine, and apply a natural, non-toxic sealant.

Two great natural non-toxic sealants are Vermont Natural Coatings Exterior Penetrating Wood Stain and Valhalla Wood Preservatives LifeTime Wood Treatment.

They are equally effective and both are safe for garden use. The Vermont Natural brand comes in a gallon bucket, similar to conventional sealants,

while the Valhalla brand is less expensive and comes in a powder form you can mix with water as needed. This sealant also requires only one coat, as opposed to Vermont Natural’s two.

How Do I Build My Raised Bed For Tomato Planting?

How Do I Build My Raised Bed?

Once you’ve chosen your raised bed size and materials, it’s time to build. You’ll need the following:

  • Lumber for the sides of your raised bed
  • A stick of 2 x 2 lumber for the inside support corners of your raised bed
  • A saw (a handsaw, miter saw, jigsaw, or circular saw will all do the job. Some hardware stores will make cuts for you, as well)
  • A drill and exterior screws.
  • Step One: Cut the sides of your bed. If you can, use dimensions that will reduce or eliminate waste. For example, a twelve foot long piece of lumber can be turned into a 2 x 4 foot raised bed without any wasted wood: 2’ + 2’ + 4’ + 4’ = 12’
  • Step Two: Cut your corner supports by sawing your 2 x 2 stick into four lengths of wood, each equal to the depth of your raised bed.
  • Step Three: If your lumber needs to be sealed now is the best time to seal it. Sealing after you build will leave some small areas unsealed. Coat all your pieces thoroughly, paying special attention to the raw, just-cut ends of your wood. Allow to dry.
  • Step Four: Assemble your raised bed. The easiest way to do this is to attach your two longer pieces (unless you are building a square, of course!) to the corner supports first. The support corner pieces will end up on the inside of your bed, and give it strength and stability.

Lay your two side pieces on the ground. Then place one corner piece underneath each end, parallel and flush with the short end of your board.

Secure with 3-4 screws on each side (be sure to predrill first so your wood does not split).

Do this for both sides of both boards. Next, place the boards with corners attached on their sides. Line up your shorter end boards so that you are making a rectangle with corners flush.

Pre-drill and attach the ends to the longer sides and corner supports, taking care not to hit the screws that are already there.

You should now have a beautiful raised bed that is ready for your garden!

How to Grow Tomatoes in Your Raised Bed Garden

Once your raised bed is built, you’re ready to choose your cultivars, prepare your site, and plant your tomatoes. Here are some best practices for raised bed tomato cultivation.

Choose the Right Tomato Cultivar for Your Raised Bed

Choose the Right Tomato Cultivar for Your Raised Bed

There are three types of tomato growth habits: determinate, indeterminate, and semi-determinate. All of these have the potential to thrive in a raised bed with proper care.

  • Determinate: Determinate tomatoes have a few main stems with abundant offshoots, which stop growing once they produce flower clusters at their ends. Their fruit matures in a small window of time (usually 2-3 weeks) so they are ideal for canning. These plants tend to be bushy, typically only growing 3-4 feet tall, and generally don’t require staking, caging, or pruning. This makes them great for smaller spaces, including raised beds.
  • Indeterminate: Indeterminate tomatoes continue growing, flowering, and fruiting all season long until killed by frost. Most heirloom varieties are indeterminate. Indeterminate tomatoes, especially those grown in a raised bed or other small space, require pruning and a form of support such as staking or cages.
  • Semi-determinate: Very few varieties fall into this category. The growth habit of semi-determinate tomatoes is a blend of the other two varieties, but these plants do not require pruning, staking, or caging.

Prepare Your Raised Bed Site

Prepare Your Raised Bed Site

Before you install your new raised bed, choose and prepare the site.

First, will your raised bed receive sufficient sunlight? Seven hours per day of direct sun is ideal.

If you live in a cool climate, consider siting your raised bed next to your house or garage, provided this area gets enough sun. The radiant heat from the building will keep your plants warmer.

Remove the sod from your raised bed area, and loosen the soil with a tiller, pitchfork, or broadfork.

Removing the sod and loosening the soil will decrease competition for nutrients and water, and help your tomato plants create a deep root system beyond your raised bed.

While some gardeners swear by putting weed cloth under their raised beds after removing the sod, it’s unnecessary and can be problematic.

Your raised bed is deep enough to block sunlight and prevent weeds from germinating, and although roots can grow past weed cloth,

the cloth can make it more difficult for your tomato plants to develop the deep root system they need.

Calculate Your Soil Needs

Calculate Your Soil Needs

How much soil do you need to fill your raised bed? This is helpful to know, especially if you are purchasing bagged soil from your local garden store or ordering a larger delivery of multiple cubic yards of soil.

Tip: For larger amounts of soil, ordering in bulk is far cheaper than purchasing bagged soil.

For each raised bed you have, multiply the length times the width times the depth of your bed to find the volume of soil you need.

For example, a raised bed that is 4 feet by 2 feet, and 1 foot deep requires 8 cubic feet of soil to fill it, or about .3 cubic yards.

Choose the Right Soil

Choose the Right Soil

Tomatoes aren’t too picky when it comes to soil, but the best choice for them is a garden loam amended with compost, with a slightly acidic pH of 6.0-7.0.

Depending on the scale of your garden endeavors, you may already have ample soil, compost, and other amendments on hand, and it would be perfectly okay to use what you have available in your raised bed. 

However, if you are starting from scratch, consider purchasing raised bed soil. Raised bed soil is formulated specifically for use in raised beds.

It is ready to use and does not require any amendments, although like any soil, you should add fertilizer throughout the season for best results.

Raised bed soil provides excellent drainage and has a pH of 5.8-7.5, which is great for all vegetables and flowers, including tomatoes.

You’ll need to add more soil to your raised bed each year, as microbes eat some of your soil and the elements take some, too.

That’s okay; topping off your raised beds with fresh soil at the beginning of each season is a great way to add nutrients and bring in disease and pest free soil at the same time.

Install Support Cages and Stakes Early

Install Support Cages and Stakes Early

If you’ve chosen to grow indeterminate varieties in a raised bed, your plants will benefit greatly from staking or caging. This is particularly important in a small space.

Without support, these vining plants will become a tangled mess of foliage on the soil where they are more vulnerable to pests and diseases.

The best time to set up stakes or cages for your tomatoes is before or immediately after transplanting.

Doing this later, when the plant actually needs support, can break foliage, drop fruit, and disturb the root system.

If you choose to use tomato cages, buy the largest and sturdiest cages you can find. You can also make a cage with stakes.

Using several five foot high wooden stakes, pound 4-5 into the ground in a 1-2 foot diameter circle. Wind twine around your stake circle to make a “cage” to support your growing plant.

Properly Space Your Tomato Plants In Raised Bed

Properly Space Your Tomato Plants

It’s incredibly tempting to skimp on space in a raised bed in order to fit in more plants, but this will negatively impact your crop.

Proper spacing is important in tomato cultivation for several reasons. The right amount of space helps prevent disease or pest infestation, minimizes competition for water and nutrients, and gives the plants’ foliage plenty of sun exposure for photosynthesis.

In general, tomato plants should be spaced 24-36 inches apart. Determinate and semi-determinate tomatoes can be spaced on the lower end of this range, with indeterminate varieties given more space.

Prune Indeterminate Plants

Indeterminate tomato varieties need to be pruned, especially in a contained space. Do this by removing the plant’s suckers, or small shoots, which emerge at a 45 degree angle between the stem and branches.

Pinching away the suckers will encourage your plants to produce larger fruits by allowing them to focus on what’s already growing. It will also increase air flow between plants and decrease their risk of foliage diseases.

Rotate Your Tomatoes

Rotate Your Tomatoes

Tomato diseases such as blight can live in the soil. Ideally, you’ll be able to rotate the location of your tomatoes each year, planting in the same spot no more than once every three years.

Of course, depending on the location and number of your raised beds, rotating crops between beds may not be practical.

If crop rotation isn’t feasible, consider switching out some of the soil in the bed each year.

At the very least, remove all dead plants at the end of the season as they may carry diseases, and don’t compost them.

In Conclusion

There are many benefits to growing your tomatoes in raised beds, including a longer season, great drainage, control over your soil, and the visual appeal of a neat and tidy raised bed.

Not only that, but building and installing a raised bed is an easy project that can be done in an afternoon, without any fancy tools or carpentry skills.

The best practices for growing tomatoes, combined with the benefits of growing in a raised bed, will help you have an incredible tomato harvest.

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