Sustainable Gardening Basics – Soil-Bed and Container Sizes

In getting started with your sustainable garden it’s important you choose the right sizes for the beds or boxes in which you’ll grow your plants.   Spacing your plants within your beds is just as important, and we’ll discuss that another time.  For today I’ll explain why you will want to plant in soil-beds or containers of 18″ wide, or  4′ wide.

There are important production and efficiency-related reasons for these sizes.  Do not make the mistake of thinking any size is just fine, or you will discover that you are not getting the yields you expected.  Remember, the “poor man’s hydroponic system” Mittleider Method is a recipe!

Widths narrower than 18″ put most plant rows too close together when planting two rows.  They also crowd the roots in some larger crop varieties.  There’s less available water, which can lead to water stress, and the soil mix in the boxes can dry out faster in hot weather, making it even worse.

Widths wider than 18″ make watering and feeding more difficult and less efficient.  For example, placing fertilizers down the center of a box or bed that’s 22″ wide will leave young plants hungry, because their roots haven’t spread far enough to find the food.  Applying two bands of fertilizer doubles the work and may still not solve the problem, depending on how well the watering system dissolves and distributes the fertilizers.  Also, the water will not reach young plants’ roots as well, and they will suffer from lack of moisture.

Even the size for the 4′-wide beds or boxes has been worked out for maximum yield and efficiency.  This size allows for planting 4 rows of most plants, and two rows of vertically-grown varieties.  Some folks mistakenly think they can get by with a 3′-wide box, and they pay heavily in lost yield, unless they’re planting carrots or onions.  The reason is that most crop varieties need the 2 feet of space between the inside rows for light and air.   Always plan for the space your plants will need when they’re mature!

The 5′-wide boxes demonstrated in Jacob’s first book, Grow-Box Gardens, are no longer recommended for several reasons.  First, it’s difficult to reach into the center of the box. Second, efficiency requires planting across – rather than lengthwise in the bed – and then watering becomes a problem.  Watering must be done by hand, since the automated watering system doesn’t work well for planting across the width of the bed.

Remember also that aisle widths are important!  We recommend 3 1/2′ widths – especially for soil-beds.  You can do alright with 3′-wide aisles if you prune properly and continuously.  Aisles less than 3′ usually do not provide sufficient light and air for large crop varieties, and thus reduce yields.  It’s also difficult to get equipment down narrower aisles.

The container depth of 8″ works very well – especially if plants can send their roots down into the native soil.  For a patio planter with a bottom – or if planting on cement, etc. a deeper box can be good, to give more room for root growth and to avoid overheating in warm weather.  Remember, however, that a deeper box takes more material to fill, which adds to your expense.  It also requires more water, and keeping the soil mixture moist is critical to your success.  And finally, the fertilizers are distributed throughout a greater volume of soil-mix, so young roots have to search for them.

Benefits to having a deeper box include aesthetics, if you’re using your Grow-Boxes in a landscaping scheme.  It also makes it easier for folks who have difficulty bending over to work near the ground.  Some people have successfully used Grow-Boxes as deep as 2 to 3 feet.

Once again, remember that the 8″ depth is least costly to build and fill, and is most efficient for watering and feeding, and then govern yourselves accordingly.  For more details, illustrations, and lots of pictures, check out the Mittleider gardening books at

Why don’t my plants grow well??

Q.  It doesn’t seem to matter what kind of soil, soil amendments, or fertilizer I add to my grow boxes, my produce is consistently miniscule and non-productive.  When I dig up the soil, the boxes are full of tiny fibrous roots.  There are several very large trees next door-20-30 feet away from my garden area.  Could it be that these roots are from the trees and are sapping all the nutrients from my garden?  What can I do?
A.  There may be several reasons, either individually or acting in concert, that are causing your crop failures.  Let’s investigate each potential problem.


1)  Trees nearby may indicate too much shade.  Are your plants getting at least 6 hours of direct sunlight each day?  If not, you will not get much produce. 8-10 hours is better – especially for plants which produce flowers and fruit. 


2)  What is the soil composition, and what are you feeding your plants?  We recommend sawdust, peatmoss, perlite, and sand – in any combination you like, but with the sand being 25%-35% by volume.  That has no nutrition, so you need to feed your plants regularly.  One application of calcium as lime in a Pre-Plant Mix and regular small applications of a complete, balanced natural mineral nutrient mix we call Weekly Feed, will assure healthy, robust plants.


3)  How often do you water?  a raised bed or container will drain faster than ground-level soil, especially if you have lightweight organic materials as a major component.  Daily watering, until water seeps out the sides at the bottom is important to assure adequate moisture to the plants.


4)  If all the other elements are properly taken care of, it would take an awful lot of tree roots to keep your plants from growing, but it is possible.  Dig a shovel-width trench the length of your containers, between them and the trees, at least one foot deep.  This should cut most of the tree roots that have ventured that far.


5)  Are the trees walnuts?  Walnut trees have a reputation for producing a substance which is toxic to some vegetable plants.  Tomatoes do not do well at all near walnut trees.  If they are walnuts, you may well have that problem.

Can you help automate the gardening process?

Q. Can you help automate the gardening process?

A. If you would like to create or expand your garden and need help with decisions and automating the planning process, the Garden Wizard, available at on the Software page, is a great tool!  Dr. Ron Guymon has devoted thousands of man hours over two and one half years to producing this multi-faceted tool for those who want help determining what, when, where, and how to plant, water, feed, etc.  It includes growing season helps for over 3,000 locations in the USA, as well as planting and feeding requirements for all common vegetable crops.

Another way to automate your gardening is to build a simple and effective watering system that will allow you to water quickly and efficiently while saving water.  The plans for this system are in Chapter 15 of the Mittleider Gardening Course – available at on the Books page.  They can be seen free in the Store section as well.