Growing Tomatoes in Planter Boxes: A Complete Guide

Tips to Grow By

Follow these tips to ensure your success growing tomatoes in planter boxes. For even more tips, check out: 10 Tips for Growing Tomatoes in Planter Boxes.

• Start with a deep planter. Tomatoes need deep, roomy planter boxes so their root systems can grow strong.
• Use quality potting mix. Skip garden soil. A lightweight blend with Sphagnum peat and perlite or vermiculite gives the best balance of air and moisture.
• Water evenly. Keep the soil consistently moist to prevent cracking and blossom end rot.
• Feed regularly. Fertilize every two to three weeks for steady growth and higher yields.
• Support early. Add cages or stakes at planting time so you don’t disturb roots later.
• Follow the sun. Tomatoes love warmth and light. Move your planter if needed to ensure at least 6 hours of daily sunlight.

Quick Tomato Facts

Before we dig into planting tomatoes, let’s have some fun. Here are a few quick tomato facts that might surprise you (Kids Fruit):

• Tomatoes are fruits. They grow from a flower and contain seeds.
• There are over 10,000 types of tomato. They vary in size, shape, and even color, including red, yellow, purple, black, and white.
• Tomatoes are 95% water. That’s why moisture consistency is everything.
• They’ve been to space. Tomato seedlings have been grown aboard the International Space Station.
• They’re state stars. Tomatoes are New Jersey’s official fruit and Ohio’s official state drink.

Why Grow Tomatoes in Containers?

Growing tomatoes in containers offers the flexibility you can’t get from a traditional vegetable garden. You can move the planter to chase the sun, protect plants from storms, or create an instant garden on your patio.

Planters also reduce soil-borne diseases and weeds while letting you control every factor that affects your crop, including soil, nutrients, drainage, and watering.

You can explore more in our companion post, How to Use Planters for Tomatoes.

The Best Tomato Planter for Healthy Roots

Your container is more than a pot. It’s your tomato plant’s ecosystem. Choosing the right one sets the stage for success.

Choosing the Right Size and Depth for a Tomato Planter

Tomatoes aren’t shy about spreading out. Their root systems need plenty of room to anchor and absorb nutrients.

• Determinate tomatoes (compact or bushy types) do well in planters 18 inches wide and 12–18 inches deep.
• Indeterminate tomatoes (the tall vining types) require at least 24 inches wide and around 2 cubic feet (about 15 gallons) of soil so the roots have space to spread.

Picking the Best Tomato Planter Material

The planter’s material affects how often you water, how well roots breathe, and how long your planter lasts outdoors.

• Plastic planters are lightweight, moisture-retentive, and won’t crack.
• Wooden planters look natural but can rot unless sealed.
• Clay or terra cotta breathe well but dry out quickly.
• Generally, it’s best to avoid black plastic, which can overheat the soil.

Want more insight into selecting a container? Read our post on The Perfect Planter for Growing Tomatoes.

Drainage is a Must

Tomatoes hate wet feet. Make sure every planter has drainage holes so excess water can escape.

Otherwise, you risk root rot, yellowing leaves, fungal diseases, and stunted growth. Soggy, damaged roots can’t absorb nutrients from the soil to thrive.

The fact is that overwatering is a common concern with container gardeners.

If you’d like to reduce the risk, self-watering planter boxes like the EarthBox^® Original gardening system do the work for you. The built-in reservoir keeps the soil consistently moist, reducing both water waste and plant stress.

Choosing the Right Type of Tomato for Your Planter Box

Some tomatoes grow in neat little bushes; others can stretch six feet or more. The variety you choose affects everything from planter size to staking needs.

Determinate Tomatoes (Bush Type)

These varieties grow to a set height (3–4 feet) and produce fruit all at once, perfect for smaller planters or first-time growers. Try Roma, Patio, or Bush Early Girl.

Indeterminate Tomatoes (Vining Type)

They continue to grow and fruit all season. However, they can get large, typically 6 feet, though 12 feet isn’t out of the question.

If you want to grow indeterminate tomatoes, have a large planter and a sturdy support system. Great options include Sun Gold, Cherokee Purple, and Better Boy.

Heirloom vs. Hybrid

Heirlooms offer rich, old-fashioned flavor but are more prone to disease. Hybrids are hardier and often yield more fruit, especially in container gardens.

“If you’re short on space, choose compact or dwarf varieties bred for containers.”
— Mark Bolt, Vice President of EarthBox^®

The Best Potting Mix for Tomatoes in Planters

Healthy tomatoes start with healthy soil. But don’t use dirt from your yard. It’s too heavy and can suffocate the roots. Instead, go with a quality potting mix made for containers.

The ideal tomato potting mix includes:

• Peat moss or coco coir for water retention
• Perlite or vermiculite for airflow
• Compost or aged manure for nutrients

Maintain a pH between 6.2 and 6.8 and add dolomite lime for calcium. It strengthens cell walls and prevents blossom end rot, one of the most frustrating tomato problems around.

Your soil selection has a significant impact on plant health and yield. Here’s a closer look at what makes the best soil for gardening containers.

Planting Tomatoes the Right Way

Planting is where your success begins. Here’s what works:

Fill your planter with your potting mix, leaving a couple of inches at the top. Then dig a deep hole and bury two-thirds of the tomato stem. Tomatoes can grow roots along their stems, which gives them a strong, resilient root system.

Water thoroughly until it drains from the bottom, then add mulch to help regulate soil temperature and retain moisture.

Set your planter in a spot that gets at least six to eight hours of sunlight a day. The more sunlight, the more sugars your fruit develops, and the sweeter your tomatoes will taste.

According to the University of New Hampshire, a general recommendation is to plant one tomato plant per four or five-gallon container.

Watering and Feeding Your Container Tomatoes

Tomatoes are thirsty and hungry plants. In planters, that means they’ll need a little extra attention.

Water slowly and deeply, soaking the soil until you see water drain out. Check the top inch of soil each day. If it’s dry, it’s time to water again. During hot summer months, your plants might need watering twice a day.

Like wet soil, soil that’s too dry has negative consequences, including wilting, poor fruit development, and disease risk such as blossom end rot.

Self-Watering Planters Remove Watering Concerns

Self-watering tomato plants, like those from EarthBox, eliminate the guesswork of watering. All you have to do is keep the reservoir filled.

The reservoir or wicking bed provides a consistent water supply. Plants can access moisture and transport it to their roots through capillary action. In short, the plants ensure they don't get too much or too little water. So, you're off the hook!

Unlike other planters, you don't have to worry about drainage holes. With traditional pots, you need them or risk waterlogging your plants, but with sub-irrigated planters you don't.

Learn more by reading this article, Why Self-watering Planters Are a Green Thumb’s Best Friend.

Feeding Your Container Tomatoes

Tomatoes are heavy feeders. They use a lot of nutrients to support their rapid growth, deep root systems, and constant fruit production. In containers, those nutrients are used up and washed away faster than in the ground, so consistent feeding is key.

Start by mixing a slow-release fertilizer—something balanced like 10-10-10—into your potting mix when you plant. That gives your young tomatoes a steady supply of nutrients right from the start.

“Think of fertilizer as fuel. You can’t expect a car to run on fumes, and tomatoes are the same.” — Mark Bolt, Vice President of EarthBox^®.

Boost Fruit Production with P & K

Once your plants start flowering, it’s time to change the menu. Switch to a fertilizer that’s higher in phosphorus (P) and potassium (K) to encourage strong blooms and better fruit set. Phosphorus supports flower and root development, while potassium helps ripen fruit and improves overall plant health.

If you prefer organic options, compost tea, fish emulsion, and bone meal are all great choices for sustained growth. Just remember to feed lightly but often. Every two to three weeks is ideal through the growing season.

Supporting Your Tomato Plants

Tomatoes can grow fast and heavy, especially in planter boxes where growth is concentrated. Without proper support, stems can bend, break, or shade lower fruit.

The best time to add support is right after planting. It keeps the root system undisturbed and ensures the vines grow in the right direction from the start.

Match Your Staking Method to Your Tomato Type

Not all tomatoes grow the same way. Some stay compact and tidy, while others turn into tall, wandering vines. The right support system depends on the kind you’re growing.

• Determinate tomatoes are compact and bushy, and do well with a medium cage or short stake.
• Indeterminate varieties need taller, stronger supports since they’ll climb and keep producing all season. It’s best to use 6- to 7-foot stakes or large cages.

If space is tight, staking saves space and improves air circulation. If you prefer low maintenance, caging gives steady, even support without frequent tying. In both cases, tie the plant stems loosely with soft ties every 6 to 8 inches as the plant grows.

Pruning Your Tomato Plants

For the best results, prune lightly through the season by removing “suckers,” those small shoots that sprout between the main stem and branches. This keeps plants open, improves airflow, and encourages fruit instead of excess foliage.

A little early structure and a bit of gentle pruning make the difference between tangled vines and an organized, high-yielding tomato plant.

Common Tomato Problems in Planter Boxes

Even experienced gardeners face the occasional hiccup. Here’s how to identify and correct the most common issues when growing tomatoes in planter boxes:

Problem	Likely Cause	Quick Fix
Yellowing leaves	Overwatering or nutrient deficiency	Check drainage holes; add fertilizer
Blossom end rot	Lack of calcium or uneven watering	Mix in dolomite; keep moisture steady
Cracked fruit	Irregular watering schedule	Maintain consistent watering
Wilted or curled leaves	Heat stress or dehydration	Move to partial shade; water twice daily
Aphids or whiteflies	Common pests in planters	Use neem oil or insecticidal soap

 

Harvesting Container Tomatoes for Peak Flavor

Harvesting tomatoes is one of the most rewarding moments of the growing season. When your plants have been nurtured from seedling to fruit, it’s time to enjoy the payoff.

You’ll know your tomatoes are ready when their color shifts to their mature hue. Deep red, golden yellow, or even rich orange, depending on the variety.

A ripe tomato feels firm yet has a gentle give when squeezed. If it’s hard, it’s not ready; if it’s soft or wrinkled, it’s likely past its peak.

How to Tell When Tomatoes Are Ready to Harvest

Timing is everything for flavor. Here’s how to know when your tomatoes have reached their peak and are ready for harvest.

• Color: Watch for a uniform, vibrant tone. Red tomatoes often begin with a pink blush before fully ripening.
• Feel: Gently squeeze the fruit. It should feel plump and a bit soft.
• Lift Test: A ripe tomato releases easily from the vine with a light twist. If it resists, give it a few more days.

For the best flavor, harvest in the morning, when the fruit is cooler and firmer. Use garden shears to snip the stem or gently twist the fruit off, leaving a small piece of stem attached. Keeping some stems in place helps them last longer once picked.

Harvesting Based on Weather Conditions

If rain is in the forecast, harvest any ripe or almost-ripe tomatoes before storms hit. Heavy rain can cause the skin to crack and split. The same goes for late-season frosts: pick tomatoes at the breaker stage (when color starts to show at the blossom end) and let them finish ripening indoors.

A tomato that’s given time to color on the vine fully will always taste sweeter, juicier, and full of summer flavor.

Tomato Growing Kits Make Growing Simple

Companies like EarthBox offer tomato-growing kits that bring everything together: planter, soil, fertilizer, and a staking system. You can skip the guesswork and get straight to growing.

Each kit includes:

• A self-watering planter box with a fill tube and reservoir
• Quality, organic potting mix
• Dolomite lime and slow-release fertilizer
• Mulch covers to lock in moisture and nutrients
• A staking system with wheels

It’s all engineered to help your root systems grow strong, your soil stay balanced, and your plants deliver a steady harvest all season long.

Let's Grow Together

Growing tomatoes in planters is one of the most rewarding ways to enjoy fresh produce at home. With the correct type of tomato, quality soil, and steady care, you’ll enjoy sweet, sun-ripened fruit in no time.

And if you’d like to skip the trial-and-error, the EarthBox^® planter box system does the hard work for you.

“With our system, you can grow better tomatoes with less effort. It’s as close as gardening gets to a sure thing.” — Mark Bolt, Vice President of EarthBox^®.

Ready to see what a few planter boxes can do? Your best tomato harvest yet is just one planting away.

Check out our tomato growing kit and all our planter box growing solutions. Join over 1 million gardeners who’ve discovered how easy and delicious growing your own tomatoes can be.

FAQs About Growing Tomatoes in Planter Boxes

Why are planter boxes better for tomatoes than pots?
Planter boxes hold more soil than standard pots, which helps regulate temperature and moisture while giving roots space to spread. That extra room creates healthier plants and better fruit production.

How big should my tomato planter be?
At least 18 inches wide and 12–18 inches deep for determinate tomatoes; 24 inches and 20 gallons for indeterminate ones.

What’s the best temperature range for container tomatoes?
Tomatoes thrive between 70°F and 85°F during the day and 55°F to 70°F at night. Protect them from frost and extreme heat for consistent growth.

Can I grow indeterminate tomatoes in containers?
Yes, as long as your planter is large and has a trellis/staking system to handle its height and fruit weight.

Why bury part of the stem when planting?
Tomatoes can sprout roots along their stems. Burying them deeper creates a stronger root system and a more productive plant.

How can I prevent blossom end rot?
Add dolomite lime to your soil and water consistently. Uneven watering or calcium deficiency causes this issue.

What’s the best way to water container tomatoes?
Water deeply when the top inch of soil feels dry, or use a self-watering planter to automate the process.

How often should you fertilize tomatoes in planter boxes?
Feed lightly but consistently. Mix a slow-release fertilizer into your potting mix at planting, then use a balanced liquid fertilizer every two to three weeks during the growing season.

Can I reuse potting soil from last year’s tomato planter?
It’s best to refresh it. Reuse part of your old mix, but blend in new compost and perlite to restore nutrients and airflow. Discard soil if last year’s plants had any disease issues.

Do planter boxes need to be raised off the ground?
Yes, slightly. Raising them improves drainage and airflow under the box, reducing mold, mildew, and heat buildup on patios or decks. EarthBox^® offers an elevated garden kit.

How many tomato plants can I grow in one planter box?
One to two tomato plants per box is ideal. Crowding leads to poor airflow, uneven watering, and smaller yields. If your planter is substantial, space plants at least 18–24 inches apart.

Can I grow other vegetables with tomatoes in planter boxes?
Absolutely. Peppers, eggplant, bush beans, okra, and basil make great companions. Avoid planting tomatoes near potatoes, which share diseases and pests.

How do I ripen green tomatoes at the end of the season?
Pick them once they start to blush, and place them in a warm, dry indoor area. Storing them in a paper bag with a banana or apple speeds up ripening thanks to ethylene gas.

Whether you’re growing your first tomato plant or your fiftieth, planter boxes make it simple. Just add sunlight, a little care, and watch your garden thrive.