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Do you re-pot soil in grow bags each year?

Tim in Colorado (5b)
6 years ago
last modified: 6 years ago

For those using grow bags, what's your procedure for reusing the bags each year? Do you completely empty the bag and "start over", or do you leave the old soil in the pot and just try to plant around last year's remnants of stems/roots? Do you reuse the old soil? What do you amend it with for the new season if you remix it?

I have about 20 7 gallon grow bags I used for my tomatoes and peppers last year. Worked well, and I initially thought I could leave the soil in place year after year. I decided to get a headstart on the season by prepping some of last years grow bags and it's becoming apparent I need to empty them out and start from scratch. Lots of old stems and roots, and the soil is way too stiff when dry. So I've been wetting them down and emptying them a few at a time into a trash can, moistening, adding a few amendments, and using a pitchfork to mix everything and break up clumps.

Just wondered what most people do with grow bag soil for each new season.

Comments (3)

  • Paul MI
    6 years ago

    Reality is one should refresh the soil every year. But in my reality, it depends upon the size of the bags and what I'm growing in them. Quite frankly, the length of your growing season will matter as well.

    If I were to grow food crops like toms, which seem to be "hungry" plants and get very large ... most definitely. If I was growing a batch of small annuals, probably not. I'd soak the old media thoroughly, remove the old plant remains, dump the old soil out and loosen it up and add new soil to make up what was removed. At this time, I would probably add some slow release fertilizer pellets. Then I'd refill the bags. The fact that I have a short growing season would have an impact as to how wiped out the nutrients would get over the season.

    If you have a compost pile, I'd recommend adding the old soil to your compost. Then after the compost had broken down, mix things up and use some of that compost soil in the bags. (You might need to add some perlite to the mix to keep it airy but that will also result in more frequent watering needed.)

  • nancyjane_gardener
    6 years ago

    Just an FYI, my former neighbor had some and they are NOT gopher proof!

  • Tim in Colorado (5b)
    Original Author
    6 years ago

    Thanks for the tips. I thought it was going to be a bigger chore, but it turned out not to be too bad. We had a warm week last week so I decided to try and tackle it early. At first it was tough to empty the bags until I realized the soil was still mostly frozen. Waited a few more days for the warm temps to do their thing and gave it another try, then it was pretty easy. Dumped 2-3 at a time into a trash can, broke it all up with a pitchfork, moistened with water, added some amendments, picked out the biggest chunks of stems/roots, and it looked like new. Still a lot of fine roots (they were tomato and pepper plants) but I assume those are OK. My mix was 4-4-1 peat-compost-perlite. Still reasonably fluffy once I got it all refreshed. The compost was good quality variety in bulk from a local landscape yard. Much cheaper that way. I don't have a truck, but I have an SUV that fits 32 gallon trash cans which is a great way to buy bulk if you don't have a truck.

    Fortunately no gophers around here. Rabbits though. But I do have the grow area fences off with rabbit fencing.