Top 7 reasons to use grow bags for growing tomatoes

It makes all the sense in the world to use grow bags for growing tomatoes. Still, I know that not everyone agrees. And every now and then I still get asked if tomatoes can grow in grow bags.

Here today the objective is to give you 7 strong reasons why you too should at least test growing tomatoes in bags.

Have you seen our tutorials on how to make DIY grow bags at home? It is not difficult and you can either follow along the step-by-step how to make your own grow bags photo tutorial or watch our video tutorial.

Top 7 reasons to plant tomatoes in bags

1. Budget friendly – without compromises

Budget friendly – or even cheap – is not in itself a good enough reason to buy or use anything. Because often cheap means loss of functionality or lack of quality.

And this is what makes grow bags such an excellent alternative. Bags are a cheaper alternative but there is no loss of quality or functionality. Even better, as you can see below, there are even unique advantages to growing tomatoes in grow bags compared to plastic or composite pots and containers.

Some of our tomato plants waiting to be moved outdoors
Tomato plants in grow bags waiting to be moved outdoors

Whether you make your own grow bags or buy them at a garden centre, you will save money compared to buying pots or containers.

2. Grow bags made from breathable fabric promote healthy roots

The grow bags for tomatoes we use are all made from breathable fabrics. And I would only use a breathable fabric grow bag made from a porous material for our tomato plants. It is key that the material lets air and water pass through.

I have seen examples where people make grow bags from plastic shopping bags and similar. These are not the type of bags for tomatoes we are talking about here. Those plastic bag type grow bags may be cheap to make using a Walmart or IKEA shopping bag, but they are more like plastic or composite pots than actual grow bags. 

Using breathable fabrics facilitate the process known as air pruning [1] where roots naturally stop growing when they reach the drier more oxygen rich soil towards the edge of the grow bag. Instead of continuing to grow, the tomato plant will use its energy to grow new roots and branching out from existing roots.

You end up with tomato plants with strong and compact root systems and greatly reduce the risk of growing pot bound tomato plants.

Growing tomato plants in plastic pots or containers often lead to so called pot bound plants. A pot bound plant is easily identified as the roots get dense and keep growing in circles. As there is no drier soil in a plastic pot, the roots simply continue growing in circles around the inside of the pot when they hit the inside of the pot . 

3. Moisture control breathable fabric

Tomato plants are thirsty plants and you need to water regularly. Still, you want to avoid over watering your tomatoes as excess water will lead to waterlogged roots and root rot.

Here grow bags made from porous material will help control and manage soil moisture levels naturally. Any excess water will naturally evaporate through the fabric and help keep the soil moist but not wet.

Grow bags do not have drainage holes. Instead the porous fabric helps drain the soil from dangerously high water levels. To help your grow bags drain better, avoid placing them on a flat surface. Good drainage will of course also require using a soil that drains well.

4. Grow bags are versatile for container gardening

Grow bags are versatile and convenient to use whether you have a small garden with limited garden space or are lucky enough to have a large garden.

Some of the advantages for home gardeners include

  • easy to move around the garden
  • reusable when stored properly
  • easy to clean and store for next growing season
  • provide a weed free growing environment in your garden
  • can be used for herbs, flowers, garden vegetables a well as other plants
  • adjustable size as sides can be folded down
  • breathable material helps with good drainage
  • can be placed close together to maximize space in small garden

5. Grow bags help control soil temperature

Potting soil can get really hot if pots or containers are exposed to full sun. Especially if the pot is made from a material that is prone to overheating like metal or from a dark coloured non-breathable material like composite or plastic.

Grow bags made from porous, breathable materials will on the other hand help regulate temperatures as excess heat can escape from all sides of the grow bag.

6. No need to fight off weeds in your grow bag garden

As long as you use quality potting soil, grow bags will give you a weed free growing environment.

7. Allows for non invasive re-pot or pot up to larger pot

Growing tomatoes in grow bags has to be one of my favourite gardening hacks.

I start tomato plants indoors early spring every year. I plant the seeds in starter pots or seed trays and transplant into larger pots when we see a minimum of four true leaves (two pairs of true leaves). 

Typically, you would need to transplant the young tomato plants into larger pots and containers up to 5 times more before placing them in their final pot, container or grow bag.

Cherry tomato plant ready for more soil in grow bag (pot up))
Cherry tomato plant ready for more soil to be added

But we have found a better way. When the tomato plant is about 30 cm / 1 foot tall we move the tomato plant to its final pot. And this final pot is in fact the grow bag where the tomato plant will stay all season.

All we do is to roll down the side of the grow bag (to make it smaller) and then only fill it with enough soil for the tomato plant we are moving.

This method works really well when planting tomatoes as the tomato plants stems will develop new roots when buried deep in soil. The method is however not suitable for plants like peppers where the stems can rot if buried in soil. 

And as the tomato plant grows we simply roll up the edge of the grow bag to make it larger. This is sometimes a gradual process where we add more soil over time. Other times we go form small to full size grow bag in one and the same pot up or re-potting.

What size grow bag is best for tomato plants?

I will answer this question as long as we first establish that tomato plants come many different sizes and varieties.

For the purpose of this article we will define three types of tomatoes. Cherry tomatoes will represent the small and medium sized determinate tomato plants that grow to a fixed size and typically stop growing larger as they set flowers and fruits (tomatoes).

Then we have the larger indeterminate tomato plants that continue to grow and produce fruits for their entire life span. We will let the beefsteak tomatoes represent these larger, indeterminate tomato plants that grow large and need a lot of support.

SizeTomato plantSoil volume (minimum)
SmallCherry tomato (Bajaja)10 litres (2,5 US gallons / 2,2 Imperial gallons)
MediumCherry tomato (Supersweet 100)20 litres (5 US gallons, 4.4 Imperial gallons)
LargeBeefsteak tomato (Striper Stuffer)27 litres (7 US gallons / 6 Imperial gallons)

Are tomatoes best grown in pots or grow bags?

Tomato plants will grow in pots, containers and grow bags as well as planted directly in your garden. But if you ask me, grow bags are the best alternative for home gardeners with limited space.

Planting tomatoes directly in the ground is of course an attractive alternative. But growing tomatoes in a fixed location in the garden does require a spot that offers 6-8 hours of full sun combined with no wind and some protection against the sun during the hottest hours of the day.

With the exception of smaller tomato plants, we use grow bags as it is a simpler and better alternative for growing tomatoes in a smaller sized garden.

Smaller cherry tomato plants do really well in hanging baskets
Smaller cherry tomato plant in hanging basket

How many tomato plants can you put in a grow bag?

When you grow tomatoes in grow bags you should plant one tomato plant per grow bag.

Give your tomato plants space to grow and develop and you will be rewarded with a rich harvest of fresh tomatoes. And trust me, no store bought tomatoes taste as good as your own tomatoes.

So are there no disadvantages growing tomatoes in grow bags?

I do believe grow bags are ideal for growing tomatoes. And this is especially true for container gardeners. We use grow bags for leafy greens, peppers, tomatoes, radishes, cucumbers and the list goes on.

But there are of course also some drawbacks or challenges that come from planting tomatoes in grow bags.

1. Grow bags can leave marks on the surface where they are placed

I place most of my grow bags on a flat surface. I have learnt the hard way that this surface needs to drain well and not stain. For me, this means placing the grow bags in a spot covered with gravel.

I have however been guilty of leaving grow bags on the patio resulting in nasty d hard to remove stains.

True, this would also apply to pots and containers placed on the patio without protection. Byt whereas pots come with accompanying saucers, grow bags are by design stand alone contaiers.

2. Grow bags for tomatoes do get heavy

Arguably also true for pots and containers but I have found that my grow bags do get larger over time.

No, it is not that the actual grow bag grows larger over time. Rather, as grow bags are inexpensive to buy – and even cheaper to make yourself at home – I have a a tendency to buy larger grow bags than I would pots or containers.

Ad with this follows that the larger grow bags for tomatoes do get heavy to carry.

3. Grow bags for tomatoes need to be watered more

The type of grow bag we use for tomatoes is made from a porous material that breathes.

With this follows that the soil will dry out quicker compared to tomato plants growing in a pot made form plastic or composite material.

And as tomatoes are thirsty and need a lot of water, this will most likely mean extra work for you as gardener.

Using grow bags growing tomatoes started from seed
Looking after some of our tomato plants in grow bags

Helpful resources:

[1] https://depts.washington.edu/propplnt/Chapters/air-pruning.htm

Meet the author: Mattias is an experienced gardener spending most of his free time on his knees among herbs, plants, and garden vegetables. For the past two years, he has been sharing gardening projects and how-to tutorials on the NordicLavender website and YouTube channel.