How to Grow Epic Tomatoes in Grow Bags

Would you like to grow giant tomatoes but lack the space for a large garden? Leave your worries behind as we delve into the wonderful world of grow bags. These containers are portable, efficient, and reusable, and they help anyone grow tomatoes easily. Follow along with gardener Jerad Bryant as we learn the best tips and tricks for producing plentiful tomatoes in grow bags.

A close-up of cherry tomatoes and vegetables growing in fabric grow bags, showcasing vibrant green leaves and clusters of ripe cherry tomatoes hanging in rows, set against a sunny backdrop.

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Whether you’ve run out of planting space or would simply like to transform your patio into a garden, grow bags are an excellent solution. These fabric containers offer the best of both worlds, as they hold water in while offering better drainage than plastic containers. 

Grow bags air prune plants, which naturally allows roots to fiber out at the ends of the container. In typical plastic or ceramic pots, roots go down to the bottom and circle in an endless search for more space. This sometimes girdles them and slows their growth. 

Use a grow bag and avoid the hassle of circling roots and degrading plastic. They are an excellent crop for grow bags, as their roots appreciate the extra airflow and drainage. 

Tomatoes typically grow as annuals in most zones, and a grow bag offers the convenience of portability. This means you can move them under cover in the fall and extend your harvest. It also means you can save your plants from extreme heat waves in the summer and move them under shade when needed. 

With some attention to soil quality, water levels, and plant care, your tomatoes will produce bountiful harvests of fruit in no time. Let’s get into it!

Glacier Tomatoes

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Glacier Bush Tomato Seeds

Yellow and Red Pear Tomatoes

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Red & Yellow Pear Blend Pole Cherry Tomato Seeds

Sun Gold Tomatoes

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Sun Gold Pole Cherry Tomato Seeds

Select a Location

A close-up of pear tomatoes with green fruit and leaves, highlighting the dense clusters .
Grow bags provide excellent portability and functionality.

The first step in creating a tomato grow bag garden is finding an optimal growing area. Tomatoes appreciate full sun, regular water, and warm temperatures. Any open area on a garden, patio, or driveway will do.

Grow bags offer peak portability and functionality, and they’ll fit in almost any locale. If your space is wide open, allow plants to ramble where they please out of their containers. They’ll quickly fill the space and start producing fruit.

If they grow in a tight space, stake them tall and tight. Other objects function well for support, like the side of a house, an old stump, or dead branches. Use whatever you can find! Below, we’ll learn how to stake them properly. 

Choose a Size

A close-up of reusable growing bags containing lush green plants on a windowsill, with additional potted plants on either side.
Opt for bigger sizes to accommodate more plants.

Selecting the right size grow bag is essential for optimal tomato performance. The minimum size is a seven-gallon grow bag, so roots have plenty of room to extend. This size also provides enough bottom stability for the upper leafy part of the plant. This size is best for dwarf and determinate varieties.

Growers in cool summer zones may use the five-gallon size, as the cooler temperatures keep the soil moist for longer. Small grow bags require more irrigation than large ones, especially during the growing season. Go with a larger container, and you’ll thank yourself come summertime.

If you have the space, try planting multiples or one indeterminate variety in a ten or fifteen-gallon size grow bag. These large containers emulate raised beds and function similarly. The larger the container, the more plants it will hold. Plan to give each tomato plant at least five gallons of space per container.

  • 5-7 gallons = 1 tomato plant (dwarf and determinates are best for this size)
  • 10 gallons = 2 tomato plants
  • 15 gallons = 3 tomato plants
  • 25 gallons = 5 tomato plants

Use Good Soil

A close-up of a large quantity of stored agricultural leaf molds spread across a vast area, accompanied by gardening tools used for handling the materials.
Compost enriches soil by enhancing both organic matter and drainage.

Good soil is imperative for healthy tomato growth. The best soil has a balanced amount of organic matter and drainage. Tomatoes are high feeders, and container-grown plants require more added nutrients than ones grown in the ground. 

For drainage, add perlite or vermiculite. Add compost, leaf mold, or fresh organic material like shredded leaves, plant cuttings, and grass clippings to increase the soil’s organic matter content. Compost is a wonderful thing to mix into soil—it simultaneously adds organic matter and drainage. 

A good ratio for the potting mix is a 2:2:1 ratio. This ratio means we’ll add two parts potting soil, two parts compost, and one part drainage material into a container. Mix it all up, and you’ll have the perfect soil blend for healthy tomato growth. 

This crop appreciates neutral to slightly acidic soil. If you’re using old soil, amend it in autumn with the right pH-balancing components. Add lime to raise the pH and elemental sulfur to lower it. Follow the application instructions on the bag to identify how much product you’ll need. New soil should have the right pH levels and won’t require amendment. 

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Find The Right Varieties

A close-up of a Berkey  plant with green fruit hanging from branches, surrounded by lush green leaves, against a backdrop of vibrant greenery.
Determinate types cease growth and yield all fruit at once.

Worldwide, tomatoes are the most widely grown vegetable crop. There are thousands of varieties now, partially due to their global presence. This means you have unlimited possibilities to choose from! 

My favorite varieties for grow bags are ‘Yellow Pear,’ ‘Sun Gold,’ and ‘Glacier.’ The first two, ‘Yellow Pear’, and ‘Sun Gold’, are pole types, and require staking. Pole types grow on long vines that ramble without support. The last type, ‘Glacier’ is a bush tomato and grows to 30 inches tall in grow bags with or without staking. 

Determinate and bush-types are best for grow bags, as their stems are easier to manage. Determinate types stop growing at a certain point, and they typically produce all of their fruit at once. Indeterminate and pole-types can thrive in grow bags, although they require at least a ten-gallon size bag and staking. 

Transplant

Once you’ve selected your varieties, find starts at a nursery or grow them from seeds. I love using seeds, as they allow me to start tomatoes before they’re available in stores. With a jump start on the growing season, I produce more than if I had bought starts.

If you are late to the season, do not worry! Starts are also an excellent option for the garden; they make vegetable growing easy. Simply find your favorites, buy them, and bring them home for planting. 

Transplanting is different when using old versus new fabric pots. Follow along and find out how to move your tomatoes into their final home.

New Grow Bags

A close-up of young tomato tree seedlings planted in black poly bags, set in sunlit green grass with a stone wall in the background.
Experiment with burying tomato stems for stronger root growth and stability.

Newly purchased grow bags need plenty of soil. Fill your bags halfway, water the soil, and let it settle. Then, place your tomato into the center of the bag. If planting multiple tomatoes in a large container, plant each at least a foot apart from the others

Once you set the baby tomato in the center, fill the soil around it until it reaches the top of the container. Water again, let it settle, and you’re done!

Some growers recommend snipping off the lowest tomato leaves, and burying the plant so that the ground is level with the area where those leaves were. This leads to increased root growth on the stem, which helps your plants support themselves when they become tall and gangly. This is not necessary, although many growers swear by it. Try it for yourself and see which you prefer! 

Established Grow Bags

A close-up of a cluster of ripe red plum tomatoes on the vine, with a backdrop of a white grow bag where they are cultivated.
Water thoroughly and top the soil with compost.

Bags you’ve already used have had their soil in them for at least a season, and probably plants growing in them already. The soil in them may be degraded, and requires additional amendments to be in tip-top shape. 

I amend my grow bags each year in autumn, by top dressing each with a thick layer of homemade compost. Organic mulches, potting soil, and materials rich in organic matter function well as mulch covers. Over time, they decompose, adding beneficial structure, nutrients, and bugs into the soil. 

If you didn’t top dress in autumn, there are other options! I recommend emptying your bags into a large tub and mixing in additional components to achieve a 2:2:1 ratio of soil. As we said above, you’ll want two parts potting soil, two parts compost, and one part of a drainage material mixed in. Consider your old soil the potting soil, and add additional compost and drainage components to achieve the 2:2:1 ratio.

Once your soil is ready, fill the bags up halfway. If they are already filled, dig a hole halfway down in the bag and place your tomato in its center. Bury your plants up to their leaves, and fill in pots with your soil mixture. Water well, and cover the soil again with a layer of compost. 

Staking

A close-up of a cherry variety with lush green leaves thriving in fabric grow bags within a container garden setup.
Use stakes behind grow bags for efficient tomato plant management.

To save space, stake your tomato plants when they’re young. As they grow, tie their central stem to the stake to keep the plants upright. Pole and indeterminate types especially benefit from having a trellis or stake to lean on. 

Bush types and small determinate varieties grow short and squat and may not need staking. If your tomato variety reaches four feet or higher, add some support, and the plant will reward you with optimal fruit production.

If the grow bag doesn’t hold onto a stake or support, add it behind the grow bag and tie the tomato to it. Then, as they grow, you can tie more of their stems to the support system. This allows for more space to plant other vegetables, and it makes for easy harvesting. 

Water Properly

A close-up of plants with vibrant red and green fruit against lush, green leaves, being watered with droplets glistening in sunlight.
Enhance water retention with terracotta olla pots.

Tomatoes love irrigation! If you cut open a tomato, you’ll see why. Their fruit is full of juicy nectar that requires water to create. Watering needs vary as the season progresses, and each stage of growth has its requirements.

As young plants, tomatoes throw out shallow roots. They’ll need consistent moisture close to their root zone until they mature into adult plants. At maturity, their shallow roots transform into deep-reaching roots that suck water up from the depths of grow bag. Keep the grow bags consistently moist, and don’t let them dry out completely.

Plants in grow bags are more susceptible to extreme temperature swings and watering irregularities. They’ll often require a good soaking once a day in high summer heat. A surefire way to avoid water stress is to set up an irrigation system that waters in the morning or afternoon, like drip irrigation. 

Another easy trick is to add an olla terracotta pot to the grow bag. The roots suck up moisture as they need from the pot as it leaches into the soil, allowing you to get more use out of your resources. This method has been used for centuries worldwide in various cultures. 

Fertilize

A close-up of a hand fertilizing a tomato plant with a green, circular tomato hanging from its branch, set against a blurred background of brown soil.
Combat blossom end rot in tomatoes with organic calcium-magnesium fertilizer.

Tomatoes are heavy feeders! Container-grown plants need more nutrients than in-ground plants because the minerals leach out of containers easily. Plan to add a dose of organic fertilizer at planting and a quarter dose every two weeks after that. 

One issue I’ve had with grow bag tomatoes is blossom end rot. This fruit abnormality occurs when the plants don’t have enough calcium, caused by irregular irrigation or pH imbalances. Fix the calcium deficiency by testing your soil ahead of planting, and providing consistent moisture through the season. 

To solve water irregularities, set up an irrigation system on a timer, and you’ll never have to remember to water again. For pH imbalances use the same materials mentioned above for amending soil. Add lime to raise the pH and elemental sulfur to lower it. 

Pollinate

A close-up of a yellow  flower with delicate petals unfolding, surrounded by vibrant green  leaves, their serrated edges catching the sunlight in a garden setting.
Shake mature tomato plants gently to enhance self-pollination and fruit formation.

Early in the season, or when pollinators are lacking, you’ll want to pollinate them yourself. Although tomatoes are self-pollinating, they benefit from pollinator activity that moves pollen around each flower. Step up to the plate and hand pollinate when the bees are sleeping. 

To do this, take hold of your mature tomato plant by its stem. Gently shake it for a few seconds and let the pollen flow. While you shake, the anthers in each flower dump their pollen down. This pollen fertilizes any other tomato flower it comes into contact with. They are more likely to form fruit when you help them with a little shake.

Harvest Continuously

A close-up of freshly picked red and orange tomatoes, their glossy skins reflecting light, arranged neatly in a rustic wooden box, showcasing their plumpness and vibrant colors against the natural wood grain backdrop.
Freeze surplus summer tomatoes for easy winter sauce preparation.

As the plants form fruit, harvest it and ripen it further indoors. Pick fresh tomatoes continuously until the plants give up with frost, and try not to let the fruit overripen on the vine. Overripe fruit tricks your tomato plant into thinking it has created seeds for the next generation, and now it can give up on forming more fruit.

Fresh tomatoes make excellent salads, especially the cherry types. Excess harvests make great sauces and salsas. Do you still have too many? Freeze them during the summertime, and thaw them to room temperature when you’ve run out in winter. Then, their skins peel easily, and you have plenty for fresh sauces and salsas! 

Cover The Soil

 A close-up of rows of white bags containing fertile coir, highlighting the rich, brown texture of the fertile coir substrate, ready for planting.
Use compost, organic mulch, or plant cover crops to protect the soil.

After harvest season is through and cool temperatures have returned, it is time to lay the soil down to rest. Cover your soil-filled grow bags with a thick layer of compost, organic mulch, or cover crops. Keeping the soil protected through the winter preserves all the beneficial life your tomatoes fostered during summer.

Over time, the top dressing decomposes and adds beneficial nutrients to the soil. Continuously give compost or organic mulch to your grow bag; you’ll never need to buy potting soil for it again. 

Grow Bag Tomato Must-Haves

A close-up of a garden setting with plants thriving in white grow bags, showcasing the vibrant green leaves and branches of the plants.
Optimal sunlight ensures robust tomato growth.

When growing tomatoes in fabric pots, here are a few things to remember:

  • Good soil: Save money and use the 2:2:1 soil ratio recommended by Jacques in the Garden, or try a tomato-specific soil mix from a nursery.
  • Regular fertilizer: Look for a tomato fertilizer like this one.
  • Proper pH: They appreciate average to slightly acidic soil, from 6.0 to 7.0. They tolerate soils down to 5.5 acidity.
  • Good airflow and avoid overcrowding: A tomato plant needs at least five gallons of space and appreciates more. Avoid planting too many in one grow bag or planting a large type in a small size.
  • Provide enough sunlight: Tomatoes love sunlight, and require at least six to eight hours of direct sun. Move your grow bags if they are in a shady spot.
  • Ensure pollination: Shake your plants gently if they are not forming fruit.
  • Keep the soil moist: Tomato roots appreciate consistent moisture and average drainage. Container-grown plants dry out quickly and may need water once a day during hot summers.
  • Harvest continuously: This keeps your tomato plant regularly forming fruit and flowers.

Frequently Asked Questions

Why do my tomatoes have black mushy spots on them?

It is likely blossom end rot, a condition affecting nutrient-deficient plants. This symptom often appears due to improper pH levels or irregular water. Ensure your plants have both corrected before addressing nutrient conditions.

Why are my plants dropping fruit?

Plants that dry out are prone to drop their fruit before it ripens fully. Water when the soil dries out, especially on hot days.

My tomato has way more leaves than flowers. What’s going on?

Plants fed nitrogen-rich fertilizer grow tons of leaves at the expense of flowers and fruit. Avoid excess nitrogen and use a tomato fertilizer with a ratio of 3-4-6 or similar.

Final Thoughts

Grow bags are perfect on patios, porches, and in nooks and crannies of gardens. Try a determinate tomato variety in a seven-gallon grow bag, and you’ll forever be converted to grow bag gardening. One plant will produce dozens of cherry tomatoes, enough for endless summer salads! Remember to keep grow bag tomatoes moist, well-fed, and in the sun, and they’ll reward you with huge amounts of fruit all season long.

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