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Best soil option for grow bags. #744382

Asked April 14, 2021, 6:35 PM EDT

As an OSU student who's a first time gardener and moves every summer, I have decided to use grow bags for my vegetable garden. Since I am planning to use a few 5 gallon bags and a couple of 10 gal bags (for potatoes), what are my options when it comes to soil. If I were to make my own, should I pick peat moss or coco coir? And what about vermiculite vs perlite? I was planning to do a 1/1/1 mix with two of the mentioned amendments and compost. Is there a potting mix I could buy locally that would be affordable and save me the trouble? I'm currently starting cukes, squash, and a few varieties of tomatoes and peppers.

Benton County Oregon

Expert Response

Thank you for contacting Ask Extension with your question regarding container gardening. You have many options when it comes to what soil medium to use. I found a few links that you may find helpful.

Excerpt from Growing Your Own OSU EM 9027 https://catalog.extension.oregonstate.edu/em9027/html

A fairly lightweight potting soil is the best growing medium for container plants. Garden soil is too heavy for container growing. Most commercially sold potting mixes are too lightweight for garden plants because they don’t offer adequate support for plant roots.

If you buy a potting mix, add soil or compost to provide bulk and weight. Or mix your own with equal parts peat moss or well-rotted compost; loamy garden soil; and clean, coarse builder’s sand. Add a slow-acting, balanced fertilizer (slow-release synthetic or organic fertilizers work best) according to container size. Add lime to bring the mixture’s pH to around 6.5.”

Either Peat Moss or Coconut coir can be used in your soil medium. Here is an interesting link from WSU covering the pros and cons of each that may help you decide which is the best choice for you. Coconut Coir vs Peat Moss: https://s3.wp.wsu.edu/uploads/sites/2080/2018/03/coconut-coir.pdf

Mixing your own generally does not end up saving you any money. Here is an article from PennState on mixing your own potting media. Homemade Potting Media: https://extension.psu.edu/homemade-potting-media

I hope you find this information useful. Have fun with your container garden project.

Deb K Replied April 15, 2021, 12:26 PM EDT

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