Q. I came across a question and answer you gave previously (another article which states that 1″ of water in the beds is needed each time you water) and it confused me somewhat. I have a question about putting an inch of standing water on the beds every day. Conventual wisdom is an inch of water per week. Are we to apply a week’s worth of water per day to the beds?
A. An example of the confusion many people experience with this subject can be found in an article by Cornell University Agricultural Extension Division about watering tomatoes. The author states that tomatoes need 1″ of water per week at a minimum. In the very next paragraph the article gets more specific and says that a single tomato plant needs between 3 and 5 gallons of water per week.
On the surface, those two statements seem to be very inconsistent, but let’s go a little deeper. Traditionally, tomatoes are grown much farther apart than we do in the Mittleider Method. In addition, traditional watering is done by flooding the entire garden area.
Let’s suppose a person’s tomatoes are planted 2′ apart, in 30′-long rows that are 3′ apart. That garden space of approximately 100 square feet would contain about 16 plants, and would require 64 gallons of water per week (assuming 4 gallons per plant).
Applying 1″ of water to 100 square feet of garden would require 8 1/3 cubic feet, or 62.5 gallons (1 cubic foot is 7.5 gallons), which is consistent with what Cornell recommends, both as to the 1″ and the 3-5 gallons per watering.
In the Mittleider Method 16 tomato plants – planted 9″ apart – will take up 12 lineal feet in a soil-bed. The width of the planting area is 10″-12″. Using a 12″ width, it would require 1 cubic foot of water each time(12′ long X 1′ wide X 1/12′ deep =1 cubic foot). That amounts to 7.5 X 7, or 52.5 gallons per week.
So, you can see that watering 1″ per day in your Mittleider Method soil-bed uses less water than watering 1″ per week by flooding.
There is more to consider, so let’s carry it a bit further. If you are growing in heavy clay soil Cornell’s recommended 1″ per week may be sufficient, because water drains very slowly from clay soil. But if your soil is loamy or sandy, or if the temperatures are hot, the water will be gone from the top 8-12″ of the soil in less than a week, and your plants will be stressing.
Tomato plants grown under traditional watering conditions have to expend substantial energy sending their roots deep into the soil, to follow the receding water, and keep from dying. This is energy we prefer to use growing and maturing fruit.
Furthermore, flooding the entire area wastes much of the water, and usually much more than 1″ depth is applied, wasting even more. Also, flooding makes the aisles hospitable places for weeds to grow, increases humidity which invites diseases, and the moisture, weeds, and cooler temperatures nurture the bugs.
All things considered, Dr. Mittleider has it figured out very well, even to the point of declaring that you will save 1/2 or more of the water you traditionally used, and promising a better garden with fewer problems with weeds, bugs, and diseases – without resorting to pesticides and herbicides.