Intensive Gardening: More from less (space)

Published: April 16, 2018

Home vegetable production is riding a wave of popularity that began during our nation's last economic recession ten years ago. The desire to grow produce with limited space and time has resulted in a renewed interest in an old gardening technique known as intensive gardening. Today often referred to as 'square-foot gardening', a term coined in 1981 by author Mel Bartholomew, it is a method that allows for maximum production in a minimal amount of space through intensive management.

Square-foot gardening gets its name from dividing intensively managed, small plots into one-foot squares. The concept basically is a modern version of a production method developed in France in the late 19th century that became known as the 'French Intensive Method'. At that time, the gardening method consisted of putting well-aged, composted horse manure in mounds about 18 inches deep, or in small rectangular structures (boxes) capable of retaining the compost. Vegetables were spaced very closely together in this structures to the point that plants would touch one-another as they approached maturity.

Whatever name it is given, intensive gardening today is not that much different from the method practiced by the French over 100 years ago. The main points to consider include: 1) A raised area (bed) is needed to provide for excellent drainage and good aeration to the roots of plants being grown; 2) The medium in which the plants are grown should be high in organic matter and fertility to promote maximum yields; and 3) Plants should be grown closely together, but not crowded.

Growing plants close to one another makes the exposure of the intensive garden very important. It must be located where plants get direct sunlight for a minimum of six hours each day. Inadequate light results in lower plant growth and yields. While shading from trees or buildings should be avoided, even the vegetables should be planted so they do not shade one another. Therefore, locate taller plants on the north side of the plot and smaller, short plants on the south.

In spite of the need plants have for light, there are occasions when shade can actually be beneficial. Cool season vegetables such as lettuce benefit when they receive shade from taller vegetables such as staked tomatoes. Additionally, afternoon shade cast on cool season crops can prolong their period of productivity.

Although most gardeners today do not have access to well-aged horse manure, the same results can be achieved with other sources of organic matter. Composted manure from other animals may be used when mixed liberally with existing soil. The organic component of the mixture should be at least 50 percent, by volume. For heavier, clay soils, the percent should be increased. Peat moss also may be used as a source of organic matter as can composted leaves.

Soil acidity is very important to vegetable nutrition. Since most vegetables grow best in the 6.0 to 6.5 pH range, limestone often must be added to the mix. As a general rule, if peat moss is used as the source or organic matter or native soil is very acid, about four to five pounds of dolomitic limestone should be added per 100 square feet. Add the limestone when the soil mixture is being prepared and incorporate thoroughly. Soil tests can be helpful in determining whether or not enough limestone was added, as well as the status of other essential mineral elements in the mix.

Plant growth during the course of the season also is a good indicator of soil fertility and pH. Therefore, observe plants carefully. Pale green color along with 'spindly' growth usually indicates that more nitrogen is needed. Also, watch carefully for leaf damage, pests or insect eggs on leaves. Destroying pests and removing diseased leaves as soon as they are detected can reduce pest severity and make the garden season more successful.

Plants growing in close proximity to one another need a lot of water. Although the leaf density of closely-spaced plants in the intensive garden form a living mulch, addition mulch can reduce water loss from the surface of the soil. Choose organic forms of mulch whenever possible.

In spite of this, additional water often is necessary. This especially is true during hot, dry periods in mid to late summer. Even though plants may survive without supplemental irrigation, production will be greater and quality better if plants receive adequate moisture. Drip irrigation systems are ideal for apply water where it is needed yet keeping leaves dry. The latter tends to discourage foliage diseases.

Deciding what crops to plant in a square foot gardening probably should be based on economics. In short, vegetables with the highest market dollar value represent the best candidates for intensive gardens. Examples of the latter include tomatoes, peppers, carrots, onions and leafy 'salad greens' such as lettuce. Avoid the temptation to grow family favorites (e.g. melons or sweet corn) which represent low-value crops given the amount of space they require.

Authorities on the subject differ in their estimates of the economic value of an intensively managed vegetable garden. Results vary according to crops grown, spacing, use of succession planting, etc. Suffice to say, however, if intensive vegetable gardening doesn't lower your grocery bill, you are doing something wrong. Add to the economic aspects the health, psychological, social and environmental benefits of gardening and it becomes obvious why the popularity of home food production continues to remain high.