With their increasing use in gardening, home gardeners may wonder, are grow bags safe? It’s clear why grow bags becoming such an important factor in growing plants. They have air-pruning capabilities. They’re a great alternative to a raised bed where the space for one isn’t accessible.
However, recent findings suggest some grow bags have plastics in them that might not be safe for plants or for the surrounding environment. In some cases, alternatives to fabric grow bags may be safer. It tends to come down to the manufacturer and what materials they use in their fabric grow bags.
With all these things in mind, we’ve compiled an examination of the dangers some grow bags introduce to the garden and how you can avoid them. We’ll also touch on how grow bags compare to alternative containers, so you can make the best decision about how to grow your food.
Are Grow Bags Eco-Friendly?
A mixture of different grow bag sizes.
Because the number of grow bag manufacturers and brands are ever-increasing, the answer to this question largely depends on the grow bag material. This is determined by the manufacturer, their company ethos, and what materials are available to them. We at Epic Gardening trust Root Pouch fabric grow bags and GrassRoots fabric raised garden beds, both made of materials that don’t leach into the soil or cause serious risks.
Plastics In The Garden
As a general rule, most gardeners have some sort of plastic in their garden – even if it’s those thin, flimsy little six-packs the local nursery sells vegetable seedlings in. Plastic pots, greenhouse plastic, PVC hoop houses, rigid polycarbonate plastic sheeting, certain kinds of landscaping fabric, shade cloth, frost covers, seed starting equipment, some tool handles or parts, 5-gallon buckets, and even grow bags all fall into this category.
In many ways, plastics are unavoidable. There are some things that plastic can do for us that other materials just can’t, and we recognize that. So to a certain point, we’re all going to find some type of plastic appearing in our garden spaces. How much plastic you use will always be a personal choice. If you are trying to remain entirely plastic-free, it’s possible, but it can be very complex to find alternatives to some of these common garden implements!
Grow Bag Materials
The reason plastic is present in most grow bags has to do with durability. Not only do fabric bags have to hold the soil and root system of plants, but they also have to hold up to the elements. Environmental conditions can be trying through the growing season, and so can frequent watering. Grow bags must retain water to some extent, and they have to be cost-effective at the same time.
For home gardeners, there are options that generally differ from brand to brand. Fabric grow bags are generally made from recycled plastic bags or are natural fabric grow bags. Both grow plants in similar ways, but natural fabric bags will not hold up as long as recycled plastic grow bags. By natural fabric, we mean materials that are biodegradable and natural such as canvas, cotton duck fabric, burlap, heavy wool, or other materials that decay.
There are varying plastics used in recycled bags. Which plastics are safe for gardening is a relevant question that repeatedly comes up. Simply put, HDPE, LDPE, and certain PET plastics are food-safe, and food-safe plastics are generally recognized as “safe” for most garden uses. Studies have shown they’re not damaging to vegetable crops or the surrounding environment when manufacturers follow regulations.
Gardeners should steer clear of some polyvinyl chlorides and all plastics in the “other” category or those labeled with a 7 inside their recycling symbol. These plastic categories have been known to leach into the soil, and some cause known health issues. Furthermore, some #7 plastics may contain BPA (bisphenol A) which is known to mimic estrogen, which may cause cancer in exposed persons.
Root Pouch grow bags are made from PET plastic that is spun from melted-down recycled water bottles. These go through an intensive process regulated by the Global Recycled Standard, and Root Pouch does everything they can to ensure their grow bags are suited for having plants grown within them. They do not add new plastics or chemicals in the manufacturing process, and their products are as safe as can be assured for use in the organic garden.
Root Pouch grow bags will break down over time like any other type of plastic. That may herald the start of questions about microplastics and their effect on the environment. Assuming that you want to avoid the risk of microplastics entirely, a fully-natural fabric bag or a DIY version of your favorite fabric bag made of all-natural, biodegradable materials may be better overall. Root Pouch does ensure single-use plastics get a second life, though – or possibly even a third, if the plastics used have been through the recycling process before!
Grow Bag Re-Usability and Recyclability
A trailer bed full of grow bags. Source: Seabonn123
We have a tremendous problem with plastic waste in the world today, and recycled plastic grow bags are part of the solution to keeping some plastics out of landfills, at least in the short term. Reduce, reuse, and recycle is the key here — and these definitely qualify as reuse!
Grow bags can last up to 8 seasons of use if they’re made of durable materials. If you’re container gardening and filling the entire bag every season, a good grow bag should keep going for a few years, at least with good aftercare. On the lower end, more shoddily manufactured bags will last a year.
Winterizing your grow bags and keeping them in good condition in extreme heat will extend their life span. Of course, small space gardeners would do well to use grow bags and woven containers that are high quality. In this case, they’ll be set for several years… but eventually, everything needs to be replaced, and you’ll have a grow bag that’s ready for retirement.
Whether or not grow bags are recyclable has to do with the recycling facility in your municipality. Some are outfitted for recycling less conventional materials, and others are only able to recycle certain types of plastic.
To see if your grow bags can be recycled, check the information about their composition on the manufacturer’s web site, and compare that to your municipal recycling capabilities. But remember: grow bags often do not include the recycling coding that other plastics do, and it may simply be that your bags aren’t recyclable. In that case, you’ve at least extended the utility of the plastic for a while, but it’ll end up in a landfill when you’re done. Even plastics hit a limit on how often they can be recycled and reused to form something new.
As of right now, we don’t know of any grow bag manufacturers who are recycling their products, but this seems like the obvious next step for the industry to take.
Are Grow Bags Toxic?
As we mentioned before, with any fabric containers (including raised beds), their material composition will determine whether or not they’re toxic. Most are made of breathable fabric woven together with some form of food-safe plastic or possibly even a fabric entirely made from food-safe plastic. Some of the cheapest options are made with plastics that are known to leach into soil, and that may cause problems for humans and the earth.
Before you spring for grow bags, it’s important that you weigh your options and look closely into the quality of bags you’re buying. If you’re tending rooftop gardens, your plants are going to be more exposed to the elements than some would be on the ground. The type of soil you’re working with will also affect how they wear over time. Poor soil quality could introduce salinity and chemicals that would otherwise be absent, and that can cause heightened damage to the bag over time. Hard water will leave mineral residues that will need to be cleaned off. Longevity is something you’ll want to research.
The short answer to this question is this: sometimes, grow bags are risky, particularly if the manufacturers are less than transparent about the quality or origin of their plastics or about their manufacturing process. However, you’re in the clear if you’ve chosen a fabric planter like the Root Pouch or the Grassroots raised bed. If you’re dealing with a grow bag that isn’t as stringent about their material composition as those two companies, you could be dealing with toxicity.
How Do Grow Bags Compare To Other Containers?
Outside of the lightness of grow bags and the expert materials some are made of, you may find fabric pots and fabric grow bags don’t work as well for your situation. Here are some comparisons of grow bags to other types of containers.
The goal of making these comparisons is to help you determine if you should purchase some fabric pots or make your own grow bags. Potentially, you may find some of the other containers listed here are better suited to your garden.
Plastic and Terra Cotta Pots
For those with less space, containers of all kinds may be the best option. Traditional pots made of plastic and terra cotta are often the most accessible and safest option. However, these don’t offer the same air circulation, and they don’t build healthier root systems via air pruning like grow bags do. Grow bags are often larger, allowing the development of deep roots, supporting root crops and salad greens alike. Unlike many plastic pots, you can have your tomatoes growing with basil and marigolds in the same bag.
Aside from passing up on a robust root system, a plastic container may also thwart your efforts to avoid toxicity. While most plastic containers intended for gardening are safe environments for plants to be grown in, bags may be a better option for some gardeners. It depends on the quality of the plastic used. Many pots for garden use are constructed of polypropylene, which should be relatively safe. A few manufacturers use PET for rigid plastic pots, but those pots often don’t last as long, aren’t as resistant to UV rays, and may become brittle with time.
Terracotta pots may be an alternative if you want to avoid plastics altogether. In this case, find pots with adequate root space, and remember to water more often than you would in non-porous plastics. Terracotta wicks moisture out of the soil into its pores, which is great for some plants that need drier soil and not so much for others that need consistent moisture, like potatoes and tomatoes. Terracotta will be much heavier than a grow bag, but is on a similar watering cycle due to that natural wicking behavior. (On the bright side, the natural wicking tendency of terracotta is what makes ollas work!)
Repurposed Wine Barrels
One somewhat biodegradable option to plant in is a repurposed wine or whisky barrel. Here you have the same amount of space as you would in a medium-sized grow bag, with a little more water retention. These barrels are BPA-free, safe for growing food, and they add a really cool aesthetic to the container garden.
Unlike fabric grow bags or raised beds, you will need to ensure they have drainage holes and cover them with heavy-duty landscape fabric to prevent the holes from being clogged with potting soil. While they have more room than a smaller bag, plants with deeper, larger root systems can get root bound in them.
While many don’t have built-in handles, barrels are sturdier and last many more growing seasons than bags do. Because grow bags are porous, they need watering much more often than wooden containers, which can hold some excess water in their walls. With wood, you miss out on the lightweight nature and felt-like texture that grow bags bring.
Metal Pots and Beds
While you need more frequent watering in grow bags than you would in a metallic container, a grow bag could still be the better option in your garden. Like other planters we’re mentioning here, it definitely depends on the quality of the type you’ve chosen. A repurposed wash tub or stock tank may seem like a good idea, but there are ways you must prepare them to make them eco-friendly and support plant health.
Ensure your tank has excellent drainage. Since most come with a solid bottom, you’ll have to make some drainage holes. If you want to skip the preparations, you could buy a corrugated galvanized steel raised bed or a corten or REDCOR steel bed, like the Birdies beds we sell in our shop. Those are ready for garden use and won’t have any modifications required prior to use.
British gardeners and those gardeners situated on coastlines may want to avoid corten or REDCOR beds due to the deterioration they are subject to in salt spray. It’s in these environments the biodegradable nature of steel is most noticeable. A regular Birdies bed might hold up better, but plastic, terracotta, and wood are best.
You may also run into leaching with certain repurposed metals. This may not affect the top growth of your container garden, but over a few growing seasons, the metal container you plant in may have broken down enough to damage your crops and annual flowers. Therefore, when it comes to metal, something prepared is best.
Repurposed recycled bags and grow bags. Source: jpmatth
Repurposed Items From Home
Maybe you’ve managed to amass a slew of plastic containers and old woven baskets, and you’re excited to get your tomato plants and root vegetables going in spring. Remember from our discussion of plastics in grow bags that not all plastics are created equally. Some may be suited to holding your milk, but they aren’t suited to the acidity that comes from organic matter sitting in them over time.
Here, it’s important to check the markings on your plastic containers and then determine whether they’ll be safe to use over time. Remember that plastics meant for food sales or storage may not be optimal in the garden. It probably won’t hurt to start a batch or two of microgreens in a clamshell tray, but that doesn’t mean it should spend lots of time in the sun!
Most reputable grow bag distributors take pains to ensure their bags are made from polypropylene fabric that is eco-friendly. These can stand up to direct sunlight, drip irrigation, and crop rotation. They’re designed to hold plants, even those that have roots that reach somewhat deeply into the soil. Your food containers can’t guarantee those same things, so they’re limited-time use and will eventually need to go into the recycling bin or enter the waste stream.
If you know your repurposed materials can withstand full sun and they can support the weight of soil and plant roots, plant away. A huge plus is added when you know your containers are biodegradable. If you have a large cardboard box that you would rather use than recycle, plant potatoes into it! Start with the flaps folded down, and tape them up as you hill your potatoes and add more nutrients to the soil.
Much like a sanitized, safe-for-food plastic container, the cardboard box will only last one season. That means you’ll have to remove the remaining box left behind in early spring if you plant in winter. However, it’s a great eco-friendly option for certain plants.
If you want to plant something that requires a lot of space, like sweet potatoes, or more plants than just one or two, you might want to go with a large raised bed or grow bag.
Frequently Asked Questions
Q: Are grow bags safe for organic gardening?
A: It depends on the brand, but reputable manufacturers that use PET plastics or fully natural fabrics in their bags that are safe for growing plants.
Q: Do grow bags have BPA?
A: Some might, so it’s important to do research to ensure you don’t purchase those that do.
Q: How long can you keep a plant in a grow bag?
A: You can keep a plant in a grow bag until you harvest, until the plant becomes root-bound, or until the bag gives out.
Q: Do Grow bags cause root rot?
A: They do the opposite, as they’re not the best water retainers. You will need to water your grow bag much more regularly than a solid container or raised bed.
Q: Do grow bags leach chemicals?
A: Some may, but it depends on what they’re made from. Look for grow bags that are made with polypropylene woven fabric. These tend to be the safest.
Q: How do you sanitize a grow bag?
A: At the end of the season, empty your bags, throw them in the washer with ¼ cup of vinegar, and wash them. Then re-shape them by hand, hang-dry them, and store them in a sanitary place.
Q: What can I use instead of grow bags?
A: There are so many options. You’ve got terracotta pots, plastic pots, repurposed household materials, cardboard boxes… the list goes on.
Q: Are grow bags better than plastic pots?
A: It depends on the quality of either. Most reputable sources for grow bags tend to be suited for plants, but they do not retain water as well as a plastic pot will. However, grow bags often have handles and are easier to move around, plus are easier to store than a stack of plastic pots. It all depends on what you need!