Grow Bags vs. Plastic Pots - Planting Containers

The How-to-Guide for Growing Plants in Fabric Grow Bags

Grow bags have been gaining popularity over the last few years as more growers see the benefits of growing plants in containers with air pruning and superior drainage capabilities. They can also be used in place of garden beds in areas with poor soil quality.

Trees, flowers, and vegetables alike can be grown in fabric bags. They are versatile, inexpensive, and hold up to years of use. Most importantly, plants of all kinds thrive in them.

TOP 5 ADVANTAGES OF GROW BAGS

1. Healthier Root System - Encourages air pruning of roots rather than root circling
2. Temperature Control - Sheds excess heat through the breathable fabric, soil warms quicker in the spring
3. Prevents Over Watering - Excess water will percolate through the fabric material
4. Easy Storage - Can be folded up and stored with minimal space during the off season
5. Versatile - Can be easily moved or planted directly in the ground

Plants Grown in Bags have a Healthier Root System

Fabric pots efficiently keep plant roots pruned and promote a more developed root system with more fibrous growth. These grow bags encourage better-formed root mass helps with nutrient uptake and the plant's overall well-being. 

These qualities are especially helpful in tree production. Trees grown in grow bags retain a better-formed root system when transplanted. Grow bags also prevent the encircling of roots that can choke a transplanted tree even as far out as several years after the initial transplant.

What grows well in a grow bag?

Most plants will grow well in grow bags as long as you consider the root space that your plants will need. Above-ground crops, like lettuce, have shallow roots that take up space below the soil equivalent to the size of the full-grown plant.

 Read the Complete Guide to Seed Starting to learn about starting vegetables from seed in cell trays and later transplanting them into a garden space. Root crops, like carrots or beets, take up space below the soil 3-4 times the size of what you see growing above the soil. We have also seen growers plant blueberry bushes in grow bags.

Are grow bags as good as pots?

Grow bags are better than hard-sided planting containers or pots for many applications. 

In pots, the roots of the plants tend to grow in circles entangling themselves, often referred to as becoming root-bound. This overcrowding increases the likelihood of having aeration and water stagnation issues, especially in larger pots that lack proper drainage. 

When the roots reach the edge of a plastic pot, they continue growing in search of more water and nutrients. This begins the process of structural damage to your plants. The roots become constricted, leading to less water and nutrient intake.

Grow bags help alleviate this issue because as the roots come in contact with the edges of the fabric pot, they sense the drier soil exposed to the air. At this point, they know they have reached their growth limit. The roots become "air pruned." This prevents overgrowth, eliminating girdling roots (roots that damage the structure of the plant). 

This air pruning leads to more fibrous root systems, including more feeder roots for more efficient nutrition and water uptake. Plastic potted plants encourage a few larger roots to dominate and encircle the pot, reducing the plant's ability to take in nutrients.

How do I know what size of grow bag to get?

The size of grow bag you need will depend on what you are planning to grow. The charts below give you a good idea of the size of each type of grow bag as well as some suggestions of what grows well in each size. 

Fabric Grow Bag Guide

(Grow bag sizes and approx. cubic ft of soil: approximate measurements if filled to the top.)

Keep in mind that you can companion plant easily in grow bags.  When planting more than one variety of plant in a bag; the plants will have less space overall but the air pruning quality of the bags will keep the plants to an appropriate size.

 Similar to the theory behind growing bonsai trees, limiting root space will limit growth to a certain point. Feeding your planted grow bags with extra nutrients will increase the overall size. 

Can I grow houseplants in a grow bag?

Grow bags are an excellent tool for housing plants indoors. They can support larger plants than containers because of their root management. They are easy to move around, especially in grow bags with reinforced handles. This mobility is helpful if plants need to be moved to benefit from southern exposure during the winter months. 

One of our favorite methods of growing indoors is to line heavier, larger pots. Using grow bags as a liner in a terracotta or decorative pot gives you the best of both worlds. The outer pot is more pleasing to the eye for interior decoration, and the plant receives the breathability that comes with a fabric grow bag.

In addition to that, plant grow bags are much more mobile when the time comes for repotting. You can easily change the exterior pot without the stress of transplanting. Being able to carry the pot and the planted bag separately is also far easier on your back. 

Do you need trays under grow bags? 

Because grow bags allow for excellent drainage, you should place a tray or protective layer between them and the surface they are sitting on. This is particularly important if you use them indoors to avoid moisture damage to your floors or furniture. 

Grow bags can be placed directly on the ground or on a deck outside. Some people choose to place them up on a rack or pallet to increase drainage. 

If you wish to use a tray underneath a grow bag, we recommend using one filled with gravel or decorative rocks. Doing so will help prevent any rot or mold growth from setting the bag in stagnant water. If you are dealing with drought conditions or trying to conserve water, check out the methods used here in our How to Keep Outdoor Plants Alive During a Drought.

Can you grow salad greens in a grow bag?

You can absolutely grow salad greens in bags. A grow bag anywhere from 2-25 gallons will work for growing lettuce and other salad greens for small spaces. The only difference will be the number of plants you can fit into a grow bag. For most types of greens, 6 inches is enough space. Meaning you could fit 1-2 plants in a smaller bag and up to 7 in a larger bag. 

If you have a larger space, a 100 gallon grow bag is a great way to grow salad greens on a porch or deck. Just give each plant around 6 inches of space from its neighbor for full-sized plants.

 If you want to grow baby greens for salads, you can sow plants every 1-2 inches and harvest individual leaves continuously. The 100-gallon bags can also be used as a raised bed out in the garden to help keep your baby greens weed-free throughout the year. 

Is it better to grow tomatoes in grow bags or pots?

We love growing tomato plants in grow bags. There are a couple of reasons why but the top one is that tomato plants grown in regular pots are highly susceptible to becoming root-bound. 

The continuous air pruning of roots in a fabric bag means your tomato plant will be growing a robust root system throughout the growing season while staying just the right size for its pot. 

Tomatoes are also a heat-loving crop that benefits from the additional warming of the soil that happens with black fabric grow bags. The leaves of tomato plants hate getting wet, and the plants generally do not like too much water. The excellent drainage supplied by the nonwoven fabric grow bag material keeps the roots happy. 

Can I Grow Potatoes in a Grow Bag? 

Growing potatoes and other root vegetables in fabric grow bags is not only possible, it can be far easier to grow them this way than in the ground. Because the entire root system is contained you will not be leaving valuable crops hiding in the dirt.

 A 7 gallon grow bag is just the right size for most potato varieties. Once the plant is ready to harvest you just dump the plant, soil and all out onto a tarp and collect all your delicious potatoes. 

For other root crops like beets or carrots, using a grow bag at least 12” tall is ideal. Because the soil is easy to loosen in a bag it is far easier to harvest one or two roots without disturbing the rest of the plants. This looser soil also means you can get taller, straighter root crops than those grown in soil that have to contend with rocks and uneven watering.  

Top 5 Plants to Grow in Fabric Grow Bags

1. Tomatoes
2. Potatoes
3. Lettuce Greens
4. Peppers
5. Herbs

Tip: It is very important that when planting that there is no air space left around the edges of the bags. You want the soil to fill out the bag entirely without leftover creases as they can lead to air pockets that can house pests or lead to root dry-out.

Growing Flowers in Grow Bag Containers

Planting flowers in grow bags has many benefits. They can be easily kept protected in the early Spring, either in a high tunnel or by bringing the plants inside if a freeze is predicted. This way you can plant your flowers far earlier to get a jump on the growing season. For more on starting flowers check out this article on Space Saving Tips for Seed Starting. 

Once the weather has settled,  your plants can be moved out to the garden to reach their glory. Fabric pots can be placed around the garden or buried in the soil or in mulch to give the roots access to more nutrients and space. A 200 gal. grow bag can be used to plant a miniature cutting garden with zinnias, sunflowers, and cosmos. 

Flowers that benefit from drier soil like dahlias do extremely well in grow bags. It also makes digging up the bulbs for division in the fall a far easier project. Growers also use bags to grow varieties of edible flowers. Check out Cultivating Edible Blooms to learn more about what flowers are often used in culinary dishes.

Using flowers to attract beneficial insects

The adult form of many beneficial insects rely on nectar producing flowers for food. The closer these flowers are to vulnerable plants the more likely you are to see pest reduction in the surrounding crops. By planting flowers fabric plant pots you can move the flowers right up next to crops that are experiencing pest pressure. 

Flowering herbs like coriander and thyme are great for attracting small insects like parasitic wasps whose larvae attract caterpillars and aphids. Nasturtiums are a favorite of the amazing, aphid eating ladybugs. You can frequently see their pupal casings hiding on the underside of the leaves as they mature into their adult form. 

For more on this topic we have put together this guide on The Importance of Beneficial Insects for Your Greenhouse. 

Temperature Control with Fabric Grow Bags

During the heat of summer and in direct sunlight, plastic pots can get quite hot. Since they are not breathable, they trap all the heat which can cook your plants. Grow bags regulate temperature due to the breathable quality of the nonwoven fabric. Excess heat can escape from all sides.

Tip: Bootstrap Farmers bags come with convenient handles, making it easy to move grow bags up to 25 gallons out of the intense sun as needed.

How often should you water a grow bag?

Grow bags are porous. They require more frequent watering than plants grown in plastic pots. However, it is harder to over-water using a grow bag, as any excess moisture can wick out of the container. If you overwater a plant in a conventional pot, they could drown and develop mold or fungus.

In the heat of Summer or areas with high winds you can extend the time between waterings by providing your grow bags with a saucer to hold extra water. 

Another method growers use with fabric bags is drip irrigation. Grow bags can be watered with ease using raised bed irrigation kits, making it easy to water multiple bags at once. These kits also include a bluetooth timer. This is helpful when multiple waterings are needed daily during hot weather.

Can you overwater a grow bag?

No, it is pretty much impossible to overwater a grow bag. The air circulation on all sides of the plants roots means they have access to oxygen and that any excess water can quickly drain and evaporate away. 

For these reasons grow bags do benefit from more frequent waterings in drier climates. If you need to water your plants less frequently you can always place them in some type of water reservoir to give them continuous access. 

Do you put drainage holes in grow bags?

There is no need to add drainage holes to a fabric grow bag. The fabric material of the bag easily drains excess water and allows plenty of air flow to prevent any rot or decay from excess moisture. If you are worried about getting enough drainage, we recommend using a growing media with extra drainage such as promix or coco coir. 

Do Grow Bags Mold?

It is possible but rare to have mold issues in grow bags. If this is the case, you may want to reconsider your growing medium or the frequency of watering. Some growing mediums are more susceptible to issues with molds as they are less penetrable and allow water to accumulate on top. This is a correctable issue with a little trial and error. Oftentimes adding perlite to your mixture will help this issue. 

While fuzzy mold growing on the surface of soil is a problem you will want to correct; It is good to know that healthy plants will develop mycorrhizae with their roots. This is a beneficial fungus that grows below the surface of the soil and resembles an intricate web. 

If you are using bark, straw or wood chips as a mulch in your grow bags you may see this amazing fungal network growing into the mulch. It helps your plants to get all of the good stuff they need from the surrounding soil and is not a problem. 

In wetter climates grow bags will occasionally grow moss on the exterior. Far from being a problem this is usually an indicator that your grow bag is a healthy growing environment. 

How do I keep my grow bag from drying out?

Frequent watering will be required during the hot months to prevent dry-out. There are also a few tricks we find beneficial as a preventative measure. Mulching the top of a grow bag will help lessen the risk of dry out.

 Another great trick is to stick the grow bags in a filled baby pool during really hot days to help retain moisture when you just can’t keep up with the watering. Lastly, use those reinforced handles to move the bags out of the direct sun or wind on days that are especially hot or windy as both of these conditions cause dry-out. 

Best Way to Clean Fabric Grow Bags

Grow bags need to be cleaned thoroughly after use. Wash fabric grow bags with a diluted detergent, followed by a soak in a diluted vinegar solution. Thoroughly rinse bags and air dry completely before storage. Taking care to clean the bags will ensure a longer lifespan for your grow bags and better health for the plants housed in them. Bags that are dirty before replanting can pass plant pathogens as any pre-used pot can.

How Do You Store a Grow Bag?

Grow bags can be folded up and stored with minimal space each season. Storing bags this way ensures repeated use of them at your farm. We recommend storing them in plastic totes or any sealed container. 

Mice will be the biggest issue you will encounter when storing your grow bags in the offseason. You will want them protected, and we also recommend storing them with cotton balls soaked in peppermint oil or dried herbs like rosemary or lavender. Mice have a rather strong sense of smell and are repelled by these scents. 

Are grow bags effective?

Grow bags are a convenient option for growers. One of the main benefits of growing in them is their versatility and mobility. They are also an inexpensive way to add to your garden or handle the overflow. They are much more lightweight, and most sizes come with built-in handles, making them easy to move to different locations. 

They are popular among RV'ers since they can be brought from inside to out quickly, allowing you to take your garden with you. Grow bags can even be planted directly in the ground to prevent transplant shock. Available in many colors and sizes, they are a great addition to any garden and make a great gift.