Growing Tomatoes In Grow Bags (Understanding Sizes & Varieties)

Growing tomatoes in grow bags is an awesome way to maximize limited space. This practice that started in England by cultivating tomatoes in bags filled with compost or garden soil has gained traction around the world because of the ease and convenience that comes with it.

As well as optimizing limited space either outdoors and indoors, other benefits of planting tomatoes in grow bags include improved yield due to the increased amount of nutrients and water available to each plant and its flexibility.

So how are tomatoes grown in bags? This article outlines everything you need to know about this system of cultivating tomatoes using grow bags. This includes an easy ‘how-to’ guide, the most suitable grow bags to use, important care and maintenance tips to ensure a healthy harvest, and much more.

What are tomatoes grow bags?

There are different varieties of tomato grow bags on sale in physical and online gardening stores. The recommended types are non-toxic and are manufactured using felt-like, breathable, polypropylene plastic material.

The grow bag’s non-woven fabric is also safe for storing foodstuff. This underlines the non-hazardous nature of the bags especially when it comes to growing tomatoes or other non-root veggies that are harvested above the ground.

The breathable nature of grow bags is one of their most endearing qualities. Excess moisture, as a result of over-watering, is easily expelled. Also, the felt-like material aids the transportation of water and nutrients through the soil.

And because of the excellent drainage, excess water goes out of the bag preventing the roots from getting drowned. The combination of good drainage and aeration helps to prevent diseases such as root rot.

Pros & Cons of Growing tomatoes in Grow bags


  1. The texture of the fabric of the best grow bags allows for what is known as ‘root pruning’. Also known as ‘air pruning’, this essentially means the development of a very robust tomato root system. This typically occurs when the older growing roots reach the edge of the fabric and stop growing after coming into contact with drier soil and air. The result is the growth of multiple new roots. Ultimately, a root system comprising of several branches develops in the grow bag. With a more extensive root system, there is a more efficient intake of water and nutrients for healthy plant growth.
  2. Compared to pots and containers, it is easier to achieve good drainage because excess water simply seeps into the fabric and quickly evaporates.
  3. Heat regulation is another advantage of grow bags when compared to pots. The breathable material of grow bags prevents the build-up of excessive heat inside the soil. This keeps the soil and root system within the optimal growing temperate.
  4. As well as being lightweight, most commercial grow bags for tomatoes are designed with dual handles making it convenient to move your tomatoes to a better location. This is important if the sun is too much for your plants and you need to relocate them to a shaded area.

On the other hand, it might become necessary to move the plants to a location with at least more hours (6-8 hours at least) of sunshine daily. With the two handles, you can easily lift and move them or even drag them on the ground to the new place.

6. At the end of the growing season, you’d love the easy convenience of cleaning out the bags before storing them. And they don’t take up much storage space.


  1. The limited space available is one of the major disadvantages of growing tomatoes in grow bags. The space constraint means a limited amount of growing medium which also impacts the amount of nutrients or water the bag can hold for an extended period or over the growing season.
  2. Knowing the right amount of water to use for the plants can be very tricky. Over-watering is a common occurrence. Though this is mitigated by the relatively good drainage of the fabrics
  3. Tomatoes grown in bags are easily tipped over by winds especially when the plants are fully grown.

The best solution is to provide some kind of support for the bags and tomatoes. Securing the plants to the balcony’s rails is one way to go about it.

  1. If your grow bags are directly on a concrete patio or balcony, they might cause serious discoloration. The best practice here is to protect the ground with some sort of plastic material.

Best Sizes of Grow Bags for Cultivating Tomatoes

When it comes to the right size to use, bigger is always better. In general, though, your grow bags should not be less than 12 inches deep and 12 inches of base diameter. This translates to a tomato grow bag that should not be less than 10 gallons in volume.

In specific terms, that is, linking bag size to tomato variety, the sizes to use are as follows:

Perhaps, you might be tempted to use smaller bags due to budgetary or sundry reasons, but this would hurt you in the long run.

The inadequate space of smaller grow bags fosters poor intake of water and nutrients leading to smaller tomato fruits. Even the fruits’ flavor can be affected.

Besides, it is more likely for smaller bags to get tipped over by a blast of wind.

How to Grow Tomatoes in grow bags: Guide

Ensure your healthy tomato seedlings are handy then follow the steps below:

  1. Get quality grow bags and potting soil from any online or garden store. Make sure you get enough potting soil for the bags. That said, the number of grow bags and the amount of potting soil you get would depend on your budget.

It is not advisable to use garden soil.

  1. Add the potting soil into the grow bags and shake each bag very well to loosen up the soil because compacted soil inhibits drainage and airflow. So shake well until the soil is well and truly loose.
  2. Choose the location that gets at least 6 hours of sunshine daily and place the bags there.
  3. Using a garden trowel, scoop out some soil to create a small hole where you can plant your healthy tomato seedling.

Plant and seedling and cover the root with the scooped soil.

At this point, you might want to add a trellis to support the plant as it grows. You could also bury a stake upright close to the plant. Then tie the tomato to the support when it starts growing.

  1. Water your tomatoes. Always water the tomatoes when the soil looks and feels dry because tomatoes need constant soil moisture to thrive.

While watering tomatoes in grow bags could prove tricky, you can make it easier by using a growth ring. Another advantage of a growth ring is that the water goes directly to the roots when watering the tomatoes.

Make sure you water regularly and when flowers appear, add potassium-rich fertilizer to aid growth and yield.

Important Tips for Growing Tomatoes in Grow Bags

– Avoid using black-colored grow bags if you live in a very hot location to prevent overheating of the roots.

– When the plants are fully grown, you could add more potting soil in extremely hot weather.

– Plant just one tomato per bag

– If you don’t have time to regularly water the plants, consider installing a drip irrigation system.

– If you want to guarantee a steady harvest of tomatoes all through the growing season, consider planting different tomato varieties.

– Add crushed eggshells to the potting soil to counter any calcium shortfall. Inadequate calcium can lead to dangerous blossom end rot disease.

Growing tomatoes in grow bags is not complicated and when done right, it can significantly increase your garden yield, regardless of space availability.