Grow-Box Sizes What's Best and Why

There are production and efficiency-related reasons for the sizes recommended for your Grow-Boxes or soil-beds. 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 method" is a recipe!

Widths narrower than 18" put some plants too close together when planting two rows. They also crowd the roots in some larger crop varieties. Also, there's less available water, which can lead to water stress, and boxes can dry out faster in hot weather.

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 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. The reason is that most crop varieties need
the 2 feet of space between the inside rows for light and air.

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, efficient planting requires it be done across - rather than lengthwise – 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 a 5’-wide bed, unless 3 watering lines are used for each 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 diligently and regularly. 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 box 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. However, a deeper box takes more material to fill, which adds to the expense. It also requires more water, and keeping the soil mixture moist is critical to 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 people who have difficulty bending over to work near the ground. Some people have successfully used Grow-Boxes between 2 and 3' deep.

Once again, remember that the 8" depth is most efficient for watering and feeding, and govern yourselves accordingly.