Ask Jack: What Kind of Soil Should I Use in My GreenStalk?

by GreenStalk Grower on March 15, 2016 5 comments

There are so many garden blogs, clubs, and book recommendations on the “best” type of soil to use for growing vegetables. I recommend using a potting mix that retains moisture well but still allows for oxygen to get to the roots. There are many varieties of potting mixes that will give you a great result but it’s important to never buy bags labeled “garden soil.” Garden soil is too dense and will make it challenging for your plants to thrive in a container garden.

Here’s what we use:

For the last 2 years, we have grown using the Pro-Mix brand with the combination of slow release Osmocote fertilizer. That combo has done well in our trials. We wanted to see what could grow in the GreenStalk system so we used that soil mixture as the base for all of our plantings.

This year, we are doing something a bit different. Instead of using a base potting mix of Pro-Mix, we are using Happy Frog brand potting mix. Here’s a step-by-step of how we have started planting this year:

I start by filling each tier half full with Happy Frog Potting Mix. Then I add a cup of Epsoma Tomato Tone. Next I add a cup of Osmocote slow release fertilizer.

It looks like this:

Lastly, I add the final layer of Happy Frog potting mix to top it off. I make sure to overfill because the mix will settle quite a bit with watering. After seeding, I leave pots unstacked and let the spring rains do the watering until plants are about 4” tall.

I enjoy testing different methods, brands, and organic options. Hopefully, this method will result in healthier happier plants. Follow our blog for updates on how my plants are growing this season with the Happy Frog mix.

If you are a new gardener looking to start a simple garden with GreenStalk, I would recommend you start with a good ready to use soil like Happy Frog, or Pro-Mix and 14-14-14 fertilizer. If you add slow release fertilizer you should be good just adding water until harvest. Gardening doesn’t have to be complicated or challenging. Local nurseries are great resources for seeds, starter plants, potting mix, and getting your questions answered about what to grow in your area.

Send your gardening questions to:


Happy Gardening!

*All opinions are mine. GreenStalk nor I receive any compensation for brands mentioned. 

GreenStalk GrowerAsk Jack: What Kind of Soil Should I Use in My GreenStalk?

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Join the conversation
  • John - March 12, 2017

    I’ve read in your news info. that there is a attempt to use a greenhouse with the vertical Tower system.
    What type of greenhouse? Length width and height, spacing of towers.
    I’m researching the potential use of a greenhouse to grow 50 towers of vegetables this year.
    What type of drip irrigation set up would be recommended on a timer system?
    In the winter months November to April in Canada, heat and lighting will be necessary.
    Does Green Stalk Garden Tower System have such accessory equipment?

  • Lori K - March 14, 2018

    I just received my first GreenStalk a few weeks ago. I have it planted, with the soil and amendments you suggest. Everything looks great so far. However, I live in the Phoenix area, where it is extremely dry. Also, we’re having extraordinarily warm weather already. My top tier is not getting enough water via the watering bowl. I’m wondering if I’m supposed to have a gray catch tray “reservoir” under the watering bowl. The watering bowl only has one small hole per “pocket” where the gray reservoirs dispense via two nice holes. Thanks for any suggestions you can send my way.

    GreenStalk Grower - March 15, 2018

    Hi Lori!

    Thank you for commenting – great question! The top water reservoir acts as a watering disk for the top planter. You do not need an extra tray underneath it. Both the top water reservoir and grey disks have one hole per pocket. If your top planter isn’t getting watered correctly, check the holes to make sure that they are clear of debris and that water is draining thru. Contact us at with any questions. Happy Gardening!

  • Laura LaMontanaro - February 16, 2019

    Hi Jack, there are so many different options on the promix potting soil, do you think you could help me out with which one I should look for? Thank you in advance!

    GreenStalk Grower - February 19, 2019

    Hi Laura!

    We personally use HP MYCORRHIZAE Pro Mix. But other high quality mixes that are formulated for containers are other good options. Happy gardening!

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