Gardening With Grow Bags. Why & Why Not

Before you jump in and start buying some grow bags let me share what I have learned over the last few years of using them in our garden.

I get a lot of questions – like – What grows well in them and what doesn’t? Will plants winter over? How to care for them? What size works best? Where to buy? What kind of soil? How much water? How much fertilizer? Why are they better than plastic or other typical garden pots? After our third year of using grow bags in the garden I have learned a lot. I will share some of what I have learned.

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What is a grow bag? Pretty much just what they sound like. They are a bag that you fill with potting mix and grow plants either from a starter plant or seed. They are generally made of a heavy, breathable fabric. Sometimes its more of a plastic which is the case for most of the potato grow bags. They generally come in round shaped, but you can also find them square and rectangular. They come in a variety of sizes from a 1 gallon all the way to 100 gallons. They may come even larger than that but I have never used one any bigger than 100 gallons. More and more commercial growing are using them for various plants.

Why are they popular? They can be reused for several years. They are very affordable. Most of them can be moved around with ease. There is not much concern about overwatering as they drain well. They fold flat for storage when not in use. The biggest perk of all — we are not fighting the weeds all the time.

Roots grow very differently in grow bags then they do in garden pots. We all know what a giant root ball is like. Round and round and round goes the tangled mess. Not so in these bags due to the air flow into them.

When the roots come in contact with the side of the bag they become exposed to the air and they stop. It’s called “air pruned.” So instead of growing round and round like they do in regular garden pots they stop at the side of the bag and more roots are put out. There is a lot less change of plants becoming root bound in grow bags because you get a more fibrous root system which allows the plant to grab more water and nutrients. That is… as long as you use the right size bag for the plant. We learned some lessons on that during our first year of using them.

Our 100 gallon full of wildflowers

Where to get them? We are finding them showing up more often in gardening supply stores and of course, you can find them online. They often come in 5 packs. A five pack of 5 gallons. A five pack of 7 gallons — and so on until you get into the bigger sizes. Most of ours are 5, 7 and 10 gallon sizes. We have two 50 gallon and one 100 gallon. You will find your best deals on prices in the late fall thru early winter. We were able to grab quite a few at a reduced price during that time span. Don’t do like I did thou. I went crazy. We have so many grow bags we don’t use and some still in packages.

50 gallon grow bag with patio tomatoes

What is the best size? That depends on what you plan to grow in them. You will see all kinds of articles and videos telling you how well you can grow a tomato plant in a 5 gallon grow bag. I don’t know how they are doing that unless they are literally drowning them with fertilizer because we tried that the first year and had a very poor outcome. The plants grew well. They got pretty big actually but never set on much for fruit. We maybe got a handful of tomatoes out of two plants and it was very disappointing. The photo below shows what I am talking about. You can even see a few tomatoes on the plants but they never turned red. Maybe one or two finally became ripe. That orange you see there are some flowers set behind the tomato.

We had a lot better luck with 1 tomato plant in a 10 gallon pot — and even grew a couple flowers or herbs in there with them.

What not to grow in grow bags: We did not have much luck growing root veggies in them. I believe it was because the bags were to small and they got to hot. I read that due to the air flow they would not get to hot. I have to disagree. That black porous fabric draws a lot of heat in my opinion. It might have been better in a much larger pot where the plants could be arranged further away from the side. We had such poor production of onions, turnips, beets and carrots that we did not even try them in grow bags this year.

What does grow well? Greens, herbs, flowers and some veggies if they are in a big enough pot. Peppers did well. The flowers must love the heat because they go absolutely crazy in these fabric pots. Greens do quite well and we have got really good results with spinach and lettuce. Herbs seem to thrive as well. I have got a great crop of parsley and lovage in these pots. This year I have a 50 gallon grow bag that I planted my entire herb garden in and they are doing great.

What about Potatoes? You can buy specific Potato grow bags. They usually have a flap on the bottom you can open and harvest from below. We just pull them up rather than bother with the flap. It really is great not to have to dig them. Gezz, it seems you are always cutting into some of the potatoes with the shovel or fork. The first year we planted too many starts in the pots. We got potatoes but they were all small. This year we planted less starts and are getting bigger potatoes. I really don’t know why potatoes do pretty well and other root veggies not so much. Following photo is about half way thru the grow period for the potatoes.

Do we need the trays under them? For some things I would say yes. It’s not necessary for others. We found, with tomatoes (as example).. they liked having the catch tray under them to keep that water coming. The potatoes do not need them and I have to keep reminding hubby of that. The plants that are real water hogs do better with the catch tray underneath. The trays come in very handy if your going to be gone for a day or so. You can fill them up and that will generally keep them going. FYI .. even if your not using trays its a good idea to place the pots on some kind of surface other than right on the ground. We have ours on pallets. The big 100 gallon pot is sitting on some concrete walking path squares that we had. Bricks would work. Black plastic weed blocker or anything that would be a bit of a barrier between the pot and the ground.

Watering: Since grow bags are a porous material it stands to reason that the water runs thru a lot faster than a regular garden pot. We do need to water them more often, especially during the really hot time of the growing season. However, they do hold moisture pretty well. It just takes some practice to find out what works best in your situation.

Fertilizer & soil: I have read over and over to use potting MIX and not potting SOIL. There are several recipe’s floating around out there for growing medium in grow bags. So far we have only used potting mix — mixed with some compost. The main thing is not to use anything that will compact. You have to fertilize a bit more than into the ground because that will be the main source of nutrients. We use a good organic, clean fertilizer once a week for everything we grow to eat. Following photo is parsley.. Look at it go. It’s in a 2 or 3 gallon grow bag.

When the garden is done: You can leave the soil in the bags if you wish. We prefer to empty them. We pour the soil out onto a big tarp and cover it with another tarp to be used for the next year. Then we washed the bags out, let them air dry and packed them away for the winter. You may want to “refresh” the soil the next year. We added some fresh potting mix and compost to the old. Not a lot either. Whatever works for you.

Can you over winter plants? I gave it a go the first year by leaving a few perennials in a couple of the grow pots. Ah NOPE.. They all died. Stands to reason considering the porous material letting the freezing cold right into the roots. Most of our flowers are annuals but I do have a few perennials mixed in. Best to take them out and plant them elsewhere in the fall. I left the herbs in there last year and they also died.

With all of that being said. I do like the grow bags for a couple of reasons that are important to us. They are affordable and we no longer have the constant fight to control the weeds. Oh sure, you might get a weed start up here or there. We just pluck them out and move on. No digging or spraying necessary. I also like that we can move them around and its a good thing. Hubby set up the potatoes right behind the tomatoes this year. On the south size. We are only growing the patio tomatoes so they stay short. Well, it was not long until the potato’s were blocking the sun from the tomatoes. No problem. Just picked up the bags and moved them elsewhere.

I also love them for flowers. I like to be able to move them around and seem to do that more often than I care to admit. They have done so very well in them that I cannot imagine ever going back to plastic pots. Although I do have a couple metal washtubs I fill with flowers for a rustic decorative look.

We have a cinder block garden and we are planning to build another one about three times the size this fall. Not because we do not like the grow bags but because it will be easier on us old crippled up folks. (smile) .. The one we have now is so handy. The height is helpful and I can sit on the edge of it and work. We will stick with the bags for potatoes and flowers. The wind was screaming when I took the below photo. We have pulled all of the turnips and most of the beets.

For years we had raised beds. Still it was the dang weeds and still it was the bending down there. The cinder blocks are more affordable than the lumber and we don’t have to worry about rot.

If you want to try some grow bags I encourage you to do so. I hope I offered some helpful information. OH.. and if your wondering about the wire around some of the bigger grow bags…. when we first set plants in one of our dogs thought that was a good place to play so we put the wire around to keep her out. Same across the cinder block garden. I am surprised the rows are still rows. LOL

Author — Linda Carlson


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5 thoughts on “Gardening With Grow Bags. Why & Why Not

  1. So interesting. I saw many for sale during Prime Days and I wondered about the uses. Thanks for explaining all that. I think I’d want the bigger ones. Do you mostly use bigger ones?
    🙂 gwingal

    • We have mostly used the smaller ones actually. For flowers, greens and herbs. This year we did use the 50 gal to put the whole herb garden in instead of individual smaller ones.. The potato bags are taller but about the size of a 7 gal round..

  2. I didn’t know you could get special potato grow bags with a flap. I’ll have to try them! Also love your petunias in the bags – just gorgeous!

  3. I didn’t know there were special potato grow bags! And your petunias are just gorgeous, by the way.

  4. Interesting! I’ve used a few here and there but never on the scale you have. As for the tomatoes, I’ve found that heirloom tomatoes don’t seem to do well in containers in general, maybe that was the problem? As for the potatoes, I wonder if they did well because the plants’ leaves got so big that they shaded the soil and helped keep it cooler, where some of the other root veggies don’t have that many large leaves and the soil got too hot? Just an idea, I don’t really know.

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