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Eco-Answers from the Pros: Recipe for Successful Container Gardens

I am considering going organic in my self-watering container garden and in doing research I found an article describing M.L. Altobelli’s fertilizer blend containing Gro Pro fertilizer, alfalfa meal, and Azomite. Other things I have read described the benefits of all these components. Could you give me a recommended ratio of these for tomatoes, peppers and eggplant? I used a potting mix blend of Coco Coir, Vermiculite, Perlite, and Vermiblend last year but will be adding 10-25% homemade compost this year. 

Container Garden.220Glad to know that you’re looking into high mineral fertilizer for your containers. I use it in containers of all kinds and types, so I know that it will work. The recipe for the basic blend is

  • 2 parts Pro Gro
  • 2 parts alfalfa meal
  • 1 part azomite
  • ½ part gympsum
  • ½ part Leonardite

I usually mix up between 300-500 lbs at a time on a tarp and store it dry in cat litter buckets (with very tight lids). The mix stores easily as long as it stays absolutely dry. If it does get wet, use it up quickly or you’ll regret it. This is a mix designed to support microbes – lots of them. Once water is added the mix, it will not be friendly to the nose.

There are a few other things you might want to look out for:

  1. You didn’t mention the proportions of your soil blend, but make sure you have enough stable carbon in the mix. Coir and vermiblend provide some, but a container garden at top production needs more than you might think. Add either bio-char or ground Leonardite to your basic mix, and then add a liquid version of humic and fulvic acids (usually from Leonardite) starting mid-July or so on a bi weekly basis. This will keep the energy up in your mix, and you’ll be able to bring your production all the way through a light frost (with other late season management – see below!)
  2. I don’t know the size of your container, but a light application of the basic mix should be worked throughout the entire container and then a more intense application worked in right around the new transplants. At a horticultural therapy raised garden that I help to maintain (mostly whiskey barrels), we rototill in about 5 lbs of the mix per barrel (using a Mantis tiller but a shovel works just as well, although more slowly) with extra calcium (usually gypsum) and Leonardite in early spring and then plant as seasonality allows.
  3. Tomatoes need a lot more nutrient support than do peppers and eggplants. We use about 3 cups of the mix in the 12″ around the tomato transplant and about a cup to a cup and a half for the peppers and eggplants. Less than that for lettuces or herbs although some is ALWAYs worked in around the plant’s roots.
  4. Water the plants in using an inoculant that contains both bacteria AND fungi. Both are needed in a container, but you want to concentrate on supporting the fungi as the hyphae will trap more of the calcium – critical to tomatoes.
  5. We also support all of the containers (on all of our sites) with liquid fertilizers and foliars as needed. It’s critical to add weekly fertilizer from mid/late July on. Roots will have filled the container and pore spaces are shrinking due to both growth and drought (I know you said that these are self-watering, but dry spaces can develop even so). Our liquid mix includes liquid fish, kelp, yucca, humates, molasses as well as microbes (same mix as above) in small, replenishing doses (microbes are also under enormous stress in containers). We keep this up until the containers finally collapse under a hard frost in mid-October.

M.L. Altobelli, Owner of M.L.’s Greenery in Motion in Westminster, MA 

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