The move towards more efficient gardening has been around as long as gardening itself! Each innovation seeks to solve a problem or improve the standard way of doing things. In the 70s, grow bags succeeded at just that!
Fabric pots were a game-changer for container gardening and, objectively, a better tool than classic terracotta or plastic pots. They were originally intended for home gardens, but design improvements have made them a modern favorite, even among commercial growers and farmers!
So, what makes fabric grow bags superior, what is the best size for your goals, and how do you plant in them? I’ll answer these questions and more. Let’s go!
My Favorite Growing Containers
Fabric grow bags are something that I actually use all the time, and I absolutely love them! This blog post is definitely not just some ploy to sell stuff.
I want to tell you the facts to help you make an informed decision. Grow bags are my go-to for greenhouse gardening, and they, along with vertical planters, are my favorite options for container gardening. I even use them for growing tomatoes in containers and growing sweet potatoes in containers!
Benefits of Grow Bags
The pros completely outweigh the cons when it comes to grow bags! They can benefit any grower, even gardeners with limited space, urban gardeners, people with poor soil, or home gardeners with strict HOA rules.
Soil Temperature - Grow bags are better at moderating soil temperature than traditional pots. The breathable black fabric allows the sun to warm the soil more quickly in the spring, and in the heat of summer, it helps excess heat escape so your plants won't overheat.
Excellent Drainage - The porous material allows water to percolate out and evaporate through the sides. Unlike traditional pots, you don’t have to worry about clogged drain holes.
Reduced Risk of Root Rot - Fabric pots are as lightweight as peat pots and more breathable than terracotta. The breathable fabric and increased drainage reduce the risk of root rot to a very slim chance.
Moveable - A boon to any container garden is its moveability. Handles on fabric pots make them super easy to move around. Plan to move to a new home soon? You can plant in grow bags and take your garden with you! They can even be used to grow indoors.
BPA Free - The polymer-based plastics some pots are made of can leach BPA into the soil when they get hot, but fabric grow bags are BPA-free! Grow bags last longer than plastic pots, and are better for the environment at the same time.
Long-lasting & Reusable - MIgardener’s grow bags are made of a weather-resistant material that allows the planter to be reused year after year! Reusable bags can be folded and stored in small spaces during the off-season, without any worry of them breaking down in the cold. Pro-Tip: When buying grow bags, make sure you know what you are getting. While most grow bags are reusable year after year, some are biodegradable and can be planted directly into the soil.
Affordable - Fabric pots are often less expensive than your other traditional container options.
Versatile - Grow bags are perfect for all types of plants and vegetables, even tomatoes, potatoes, flowers, houseplants, fruit bushes, and small trees!
Air Pruning - All fabric grow bags are made from breathable material that allows air pruning to occur naturally on plant roots!
What Is Air Pruning
All types of pots and containers used to have one common drawback. As plant roots grow through the soil, they reach the edge of a regular pot, turn, and begin to grow in a circle. Over time, this creates a restricted or potbound root ball—not in a fabric pot, though!
Air pruning happens when roots grow through the fabric pot and come into contact with air, then they die back at the ends (or are pruned by the air). This encourages the plant to grow another root directly from the source.
That means you are doubling the plant's root mass and eliminating the tendency for roots to become potbound. This creates a far healthier root system, leading to a healthier plant! Developing this pattern early will increase the chances that your plant will form a natural root system if you choose to transplant it into your garden.
Pro-Tip: My favorite seed starting trays also feature “air prune technology”! Bootstrap Farmer’s 6-cell plug tray inserts and 4-cell plug tray inserts have air-pruning slits along the sides of each cell to prevent root circling on seedlings and encourage more vigorous growth.
Fabric Pot Sizes
MIgardener’s grow bags come in the following sizes:
3 Gallon - 9.5" diameter x 9" deep
5 Gallon - 11.5" diameter x 10" deep
7 Gallon - 13″ diameter x 12″ deep
10 Gallon - 15" diameter x 12" deep
15 Gallon - 18" diameter x 12" deep
20 Gallon - 20" diameter x 15.5" deep
100 Gallon - 4.16 feet in diameter x 12” deep
The 3-gallon size works well for a single plant, such as a houseplant or annual flowers. The 5-gallon size works well for a single small to medium-sized plant like a pepper, or multiple small plants like herbs or leafy greens.
The 7-gallon grow bag can hold most garden vegetables, including cucumbers, eggplant, peppers, tomatoes, and cabbage. With a 10-gallon fabric pot, you can grow all of the same things as the smaller pots, plus more. It will hold long-season root crops, a tomato plant with basil around it, loads of spinach, strawberries, a small flower garden, salad greens, or a berry bush.
A 15-gallon or 20-gallon grow bag is so large that you can pretty much have a mini raised bed in just one container. They can be used to grow root crops like garlic, potatoes, carrots, onions, and beets. They will also hold flowers, vegetables, berry bushes, or even some dwarf trees. Pro-Tip: Notice that the 20-gallon grow bag is the deepest size, which makes it ideal for perennials or deeper-rooted crops.
The 100-gallon grow bag can be used in place of a raised garden bed for large plantings, greenhouse gardening, and other above-ground gardens.
How to Use Grow Bags
Planting in grow bags is pretty straightforward. These steps will help you navigate the particulars:
Location - Choose a location that will provide enough sunlight hours for your plants to grow. The great thing about grow bags is that you can always move them later! (If you are growing indoors, make sure you know how to use grow lights optimally!)
Fill Grow Bags - It is important to use well-draining potting-specific soil, not topsoil or bagged compost! Good potting soil should be fluffy and soft, contain perlite or vermiculite, won’t pack down, and has good porosity. I recommend Pro-Mix, Happy Frog Potting Soil by FoxFarm, or homemade potting mix. Pro-Tip: To make a great homemade potting soil, use this seed starting mix recipe and increase the size of the perlite for better aeration.
Plant - Transplant seedlings or plants into your grow bags.
Fertilize - Apply a well-balanced, slow-release fertilizer like Trifecta+ to provide essential nutrients for your container plants. You will need to fertilize about 25% more when using fabric grow bags than you would with a standard pot. Every part of a fabric pot drains and breathes, so more nutrients leach out. I fertilize heavy feeders in grow bags about once a month.
Water - Thoroughly water after planting, then plan to water your grow bags about twice as often as standard pots. They will dry out quicker than standard pots because they are more breathable.
How to Transplant From Fabric Grow Bags
It is uncommon to need to transplant from grow bags, but you can do it. It is a little different than transplanting from a traditional pot, though.
In a standard pot, the roots coil around and around, enabling you to basically pull the plant right out with no problem at all. In grow bags, the roots will grow into the fabric a little and kind of stick to the bag like velcro.
You do not want to take the grow bag, flip it upside down, and dump the plant out, because you will damage the roots. Instead, you need to roll the sides down until you can lift the plant out.
