ROW SPACING SHOULD ENHANCE EFFICIENCY
by Vern Grubinger,
Vegetable and Berry Specialist
University of Vermont Extension

The way vegetable rows are arranged in the field depends on how much space a crop needs, as well as the seeding, transplanting and cultivation equipment to be used. Row spacings that give the highest yield for particular crops may not be suitable for cultivating weeds or for promoting air circulation to prevent development of disease. They may not be the best when it comes time to harvest, either. Extension publications list a dozen or more different row spacings  that optimize the yield of various vegetables, yet many growers use just one system of arranging plants in order to enhance the efficiency of field operations. Ideally, the arrangement of rows conforms not only to tractor wheel spacing, but also to equipment used to form beds, set transplants, control pests, and harvest the crop, resulting in a production system that's suited to the farm from start to finish. Here are examples of planting systems from 3 different farms.

David Trumble, of Good Earth Farm in Weare, NH, grows 40 species of vegetables on 3 acres of land to supply the 80 families in his Community Supported Agriculture program. In the past he used many different row spacings and a lot of hand labor in an effort to optimize the yield of each crop, but found that this approach actually hurt his yields because without mechanization his weed control wasn't very effective. Now, using a 2-row transplanter and an Earthway push seeder, he plants everything in double rows, 24 inches apart, on flat ground. Before planting, cover crops are turned in with a heavy disk harrows. Then the seed bed is prepared with a Perfecta II field cultivator, making a pass every 2 weeks, which knocks back weeds until all the crops are planted. A John Deer high clearance tractor with tires on 6 foot center is used to pull the transplanter and to cultivate. Shortly after planting, a belly-mounted basket cultivator is used for the first few passes, then home-made sweeps are used when the crops get bigger. This way weeds are controlled within a few inches of the crops so the only hand hoeing is right in the rows. This system saves David hundreds of hours of planting time and weeding time over his old method. Since he has no irrigation, it also helps that he's able to plant a lot of crops quickly when the soil moisture is just right, and by getting all the plants in fast he can get started early with cultivation.

Paul Harlow and Dennis Sauer raise 60 acres of vegetables at Harlow Farm in Westminster, Vermont. To enhance the speed and efficiency of field operations in order to meet the demands of  wholesale markets, the dozen or so crops they raise are grown on a 2 row/2-bed system. After cover crops and manure are incorporated, raised beds are formed, 2 at a time, using an International Hydro with tires spaced 88 inches on center. Large listers throw up a ridge of soil, which is later run over with sets of Lilliston rolling cultivators to kill weeds and smooth the surface. Then a pair of bed formers press the ridges into beds that are 32 inches wide at the top. The tractor is fitted with narrow tires to avoid breaking down the edges of the beds. Each bed gets planted with 2 rows of crops, 14 inches apart. Direct seeded crops such as carrots, beets, parsnip and turnips are sown with a Stanhay precision seeder. Transplanted cabbage, lettuce, peppers and kale are set using a 4-row Lannen transplanter. Transplants are pulled to the field in large custom-built carts that are parked at either end to reduce travel time back and forth to the greenhouse. Six people can set 5 to 6 thousand plants per hour this way.

Cultivation after planting starts with Lilliston rolling cultivators, mounted on the back of a Kubota high clearance tractor that works one bed at a time. There are 2 gangs in the middle of the rows and one gang on the outside of the rows behind the tractor. Hilling sweeps work the sides of the beds. This combination provides hilling action that leaves a crown of soil which buries weeds around the plants. Once the plants have sized up, a 4-row cultivator is used which covers 2 beds at a time. It has 8 shanks with ‘tender plant hoes' mounted next to the rows. These hoes have an upright guard to protect the plant, and a knife which is parallel to the soil surface and cuts weeds just below the soil surface. Properly adjusted, this unit can cultivated an acre in one hour.

David and Chris Colson of New Leaf Farm in Durham, Maine, grow 4 acres of  vegetables primarily for direct sale to restaurants. After plowing under winter cover crops, the soil is fertilized with mineral nutrients and disk-harrowed before 4-foot wide beds are formed 1 to 2 weeks later. Lettuce and leafy greens are grown in 3 rows per bed, with 16 inches between rows and plants staggered across the bed. Broccoli, peppers, and tomatoes are grown in double rows 24 inches apart on the bed. Summer squash and winter squash are grown in a single row per bed.

Transplanting is done with a homemade unit pulled by the Kubota high-clearance tractor with a creeper gear. The transplanter is set up on a tool bar with 2 seats facing backward, one on each side of the 4-foot bed. Narrow, 1-inch shanks are set on a tool bar to open the appropriate number of furrows per bed into which the seedlings are placed by hand. Transplants are carried on a rack in front of the workers. About 1200 plants per hour can be set this way.

A few weeks after transplanting, a basket weeder cultivates close to the crops grown in multiple row crops. When these crops grow large, and for the single row crops, cultivation is performed with shovels between the rows and half-sweeps next to the rows.

As you see, there isn't a single recipe for row spacing to enhance efficiency. Have you got a planting system that really works well?

10/98
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