» Container Vegetable Gardening – Size, Soil Materials, and Recommended Fertilizers

Container Vegetable Gardening – Size, Soil Materials, and Recommended Fertilizers

First off, you must have full sunlight and adequate water to have a successful vegetable garden, so find an all-day sunny spot with a good source of clean (not necessarily drinkable) water before you do anything else.

The next issue you’ll face is the details of how to build, level, fill and fertilize your containers.

Opinions differ widely regarding the answers to the following key questions about creating a container garden. The right answers, if followed, will go a long way toward assuring your success in growing a bumper crop of healthy and tasty vegetables.

1. Should top-soil be used, either by itself or mixed with other materials? 2. Should manure and compost be used for the planting medium or soil-mix? 3. What is the best ratio of materials to use for a container vegetable garden? 4. Is it important to use organic fertilizers in addition to the soil mix? 5. What size is best, in order to maximize yield in the minimum amount of space? 6. How deep does the container need to be to provide adequate space for roots?

  1. First of all, top soil is NOT recommended for use in containers, because it 1) is heavy, 2) is difficult to work with, 3) does not drain as well as other options, and 4) often contains one or more of the 3 “baddies” – disease, weed seeds, and bugs.
  2. Every gardener should also consider the following three issues very carefully before using manure and compost in containers, raised-beds, or any other type of vegetable garden, especially as the only or even the main ingredients in the soil-mix.
    1. As much as 95% of the composted materials available to the typical family gardener have NOT been sterilized, or even heat-treated in the composting process. And yet in order to have clean materials they must have been composted at 140 degrees or more for about 3 weeks, which is the time it takes to thoroughly compost organic materials aerobically, and that’s the only sure way to remove diseases, weed seeds, and bugs.
    2. In addition to the great potential for problems with disease, weed seeds and bugs, using manure and compost, even just for fertilizer, leaves you guessing as to what nutrition you are giving your plants. You never see the list of plant nutrients or their percentages on a bag of manure or compost, because no-one KNOWS what they are.
    3. And the third reason you need to be cautious about using manure/compost is that using them can often lead to a salinity problem and burn your plants. For example, applying 2″-3″ of manure to the planting area of a soil-bed or container adds 10#-15# of fertilizer salts all at once to the soil in a 30′-long bed or box. That’s more salt than the soil should have in an entire growing season! Imagine the effect of applying that much manure to the entire garden or worse yet, making it 25-50% of the entire soil mix, both of which are often done by enthusiastic organic gardeners!

3. Rather than using manure and/or compost in your container garden you will be wise to use two or more CLEAN ingredients for your soil-mix, including 30 to 35% sand (by volume) mixed with any combination of the following – sawdust, perlite, peat moss, ground-up pine needles, coconut husks, coffee hulls, rice hulls, or vermiculite – depending on cost and availability.

4. Plants cannot “eat” or even use animal excrement or compost. Both must fully decompose and their organic parts must revert to water-soluble inorganic minerals before plants can access them. Plants need small, measured and balanced amounts of 13 natural mineral nutrients dissolved in water and absorbed through the root hairs over the entire course of their growing cycle, rather than a large application of salts at one time.

For real success in your garden you must give your plants exactly what they need for sustained healthy growth. I recommend applying only about 7 OUNCES of mineral salts per week to a 30 foot-long bed or box, which is the amount applied weekly in a Mittleider garden.

Get the Mittleider Gardening Course book at to discover how to do it yourself – instructions and natural mineral formulas are all there.

5. Now briefly, let’s discuss ideal sizes for your containers. Any length is fine, depending on available space. But the width of both the container and aisles is important. You do not want to waste precious space in your garden, but plants need light and air, so the ideal width is beds of either 18″ or 4′, and aisles of at least 3′, and preferably 3 1/2′. Here’s why:

An 18′ width allows two rows of most plants, with room for light and air, plus feeding, watering, weeding, and harvesting between the rows. And a 4′-wide bed allows 4 rows of most plants or 2 rows of very large or climbing plants. Details on growing vertically are the subject for another article, but suffice it to say that you can at least double or triple your yields by growing vertically.

6. And you only need container frames 8″ high. If possible it’s good to set them on existing soil, so your plants’ roots can go into the native soil and get additional nutrients, but it’s not necessary. You can even grow healthy plants on a driveway, deck, or even a flat roof! Remember you’re feeding them everything they need with the natural mineral nutrients.

Good Growing!