Square foot gardening for Michigan gardeners

For Michigan gardeners without much room to grow vegetables square foot gardening may be just the type of gardening you need. Square foot gardening is also called bio-intensive gardening. It’s a method of planting in deeply enriched soil so that mature plants nearly touch each other, without rows between them. Square foot gardens are intensely managed to get the optimum harvest from the space available. Any kind of vegetables, herbs, small fruit and flowers can be grown in a square foot garden.

Square foot gardening can be done directly in the ground or in raised beds or containers. The soil for intensively planted gardens- square foot gardens- must be very well supplied with nutrients and organic matter. If your garden soil is poor in texture or has poor fertility it must be enriched before square foot gardening is attempted. Work plenty of aged manure and compost into the soil and add a balanced fertilizer such as 5-10-5 in the amount recommended on the package, generally that is 3 lbs per 100 square feet. Slow release fertilizers work best.

For containers and raised beds a high quality fertilizer enriched soil-less mixture would be ideal. Using a soil-less mix avoids bring weed seeds to the garden. Garden soil mixtures that don’t contain fertilizer should have fertilizer added as recommended above. The label must tell you if the planting mix has fertilizer.

Square foot gardening doesn’t mean that all plants are grown within one square foot. Some plants will require more than 1 square foot of space to grow well and other plants can be planted 6-8 plants per square foot. There is a chart at the end of the article to help you correctly space plants. While plants don’t need to have rows between them you will need rows for you to access and care for the plants.

To begin square foot planting beds measure and mark the planting area. To find the square footage of your planting areas multiply the length of the bed by the width. Beds can be as long as you have space for, but most people need beds between 3 and 4 foot wide to be able to harvest and weed plants throughout the bed, reaching in from either side. A minimum of 2 feet for rows between beds is suggested. Raised beds and containers should be measured also. Square or rectangular shaped beds are the simplest to work with but any shaped bed can be used.

A 3’ wide by 10’ long bed is 30 square feet. An example of what you could harvest from this bed under good conditions would be; 15 lbs of broccoli or 25 lbs of green beans or 45 pounds of carrots or 50 lbs. of leaf lettuce or 60 lbs of tomatoes.

The soil on open ground should be loosened to a depth of 8-10 inches minimum. Containers for shallow rooted crops can be as little as 6 inches deep but most raised beds and containers should be about a foot deep. Shallow rooted crops are greens and annual herbs.

To plant in a square foot garden you’ll need a yardstick or ruler. Consulting the list below you set plants or seed the required distance apart. Measure from the center of one plant to the center of the next for proper spacing. If seeds come up more thickly than the recommendations for spacing you will need to thin them. You fill the entire bed with plants spaced an equal distance apart. Each bed or container can be devoted to one type of plant or plants can be mixed to best utilize space.

When plants are mature their foliage should nearly touch and shade out weeds. But until the plants get to that size you’ll need to hand weed and mulch plants. Space is limited in square foot gardening and there is no room for weeds to share. When mature the plants will shade the soil and cause less water to be lost to evaporation but until then watering will need to be frequent because there are more thirsty plant roots sharing the same space. Self watering containers are great for square foot gardens.

The advantages of square foot, bio-intensive gardening is that you harvest more food from the same space that is conventionally planted and concentrate the good stuff like compost and water just where it is needed. But there are some disadvantages. Plants may be stunted and grow poorly if too crowded or the soil fertility isn’t good. Square foot plantings may have more problems with fungal disease because the plants have little airflow between them. And intensively planted areas of one crop may attract more harmful insects to them than mixed beds.

Here is the spacing for some common garden plants planted in a square foot garden.

Asparagus- 12”

Basil- 8”

Beans-bush- 3”

Beans - pole -4”

Beans lima- 6”

Beets- 5”

Broccoli-Brussels sprouts- 16”

Cabbage - small- 15” large - 18”

Carrots - 3”

Cauliflower- 15”

Cilantro- 6”