Some of you who grow in containers may want to grow in pots of different sizes, and will need to know how much Pre-Plant and Weekly Feed natural mineral nutrients to use.
Starting from the basics: Dr. Mittleider tells us to mix 1 1/2 ounce (3 tablespoons, or 9 teaspoons) of Pre-Plant into the soil of an 18″ X 18″ X 2 3/4″ square flat, and 1/2 that amount of Weekly Feed. All of this before planting seed or seedlings. Let’s do the math and see how much soil we have, then we can translate it into other size containers. 18 X 18 X 2.75 = 891 cubic inches. With 1728 cubic inches in 1 cubic foot, we have .5156 cubic feet of material in an 18″ square flat. We will round to 1/2 cubic foot.
Suppose you have a 6″ round pot that’s 6″ deep, and want to know how much to use. Multiply pi X radius squared X height, or 3.14156 X 9 X 6 = 169.64. Divide by 1728, and you have .098, or 1/10th of a cubic foot.
Since you will apply 9 teaspoons of Pre-Plant to 1/2 cubic foot of material, you would apply 2 scant teaspoons to the soil in your 6″ pot. Plus, you apply 1 scant teaspoon of Weekly Feed.
For on-going feeding of the plants in your pot, you either water with the Constant Feed solution of 1 ounce (2 tablespoons) in 3 gallons of water, or you can sprinkle 1 scant teaspoon of WF on the surface and water it in.
Now suppose your pot is 6″ square, instead of round. Multiply 6 X 6 X 6 = 216 cu in. Divide by 1728 = .125, or 1/8th of a cubic foot. Nine is to .5 as X (the unknown) is to .125 = 2.25. So you apply 2 1/4 teaspoons of Pre-Plant and 1 1/8 teaspoons of Weekly Feed to a 6″ square pot of soil mix. Did everyone follow that? Probably not, but if you will follow those simple formulas you can know how much PP and WF fertilizers to apply to any size container you might be using.
Isn’t it nice to know what you’re doing, and be able to eliminate some of the unknowns in the gardening equation? For an excellent book on growing in containers get Gardening By The Foot (NOT Square Foot Gardening) by Jacob Mittleider, available at www.growfood.com
P.S. The Mittleider Gardening books and Manuals teach all you need to know about this subject, and can be purchased in the Store section, or as digital downloads.