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Starting Your Commercial Vineyard
By Mary C. Halbrooks
Establishment of a vineyard is a long-term investment with an expected life span of 20 to 25 years in Florida. Costs to establish one acre of bunch grapes may range from $3500-$4500, not including land investment. Grapevines purchased from a commercial nursery will comprise approximately one-third of total costs. Comparatively, establishing a muscadine planting will generally be less expensive because fewer vines are planted per acre. Other that plants and land, major costs include posts, wire, irrigation, and machinery.
Grapevines receiving proper care will begin to bear fruit in the third growing season. Yields will increase gradually through year six when full production potential will be reached. In successive years, yields will be consistent if the vines are pruned properly each winter. On central Florida sandy soils, yields of 3-6 tons per acre can be expected, depending on variety and level of input. Yields in north and west Florida appear to be similar through long-term production records have not yet been established.
Selecting A Site
In Florida, soil type is the major consideration in site selection. Soil should be well drained for grape production. There are two major grape growing regions according to soil type in Florida. Central Florida is characterized by moderately-drained, fine sands and upland soils with underlying clay at about three feet. North and west Florida soils are heavier, characterized by sandy or loamy subsoil.
Soils not suitable for viticulture are excessively drained deep white sandy soils, or the poorly drained sandy organic soils such as marl, peat and muck. On soils where the water table is close to the surface, raised beds, and possibly drainage tile, will be necessary to prevent root damage due to flooding during the rainy season.
Topography is also an important element in site selection. Sloping land provides good air drainage, aiding in frost control. Low areas or cold pockets should be avoided. Sites should be free of erosion hazards. Generally, mechanized harvesters and other machinery can be operated easily on slopes of up to 12 percent.
Preparation of the vineyards site may involve one or more of the following: clearing, rototilling or discing; construction of raised beds or installation of drainage tile; erosion control; plowing in cover crops 90 days prior to planting; marking out the rows for planting; seeding Bahia grass in bare middles; well digging and pump installation.
Prior use of the vineyard site may determine other preparation requirements. Soils previously under cultivation should be tested for residual herbicides or pesticides, or an over-limed condition, which would be damaging to grapevines. Presence of perennial or persistent weeds or brambles may require systemic herbicide application. Soil compaction or a plow pan may be a problem on overworked soils, especially on the heavier soils, especially on the heavier soils of north and west Florida, and may require subsoiling. The recommended pH range for grape production is 5.8-6.2. Soil testing is needed prior to vineyard establishment to determine pH and base levels of phosphorus, potassium, calcium and magnesium.
Planning and Layout
Vineyard layout and design traditionally requires that rows be arranged in blocks with avenues between, running perpendicular to the rows, to facilitate access and provide extra turnaround space for machinery. Direction of rows is generally north to south as this arrangement allows for maximum interception of sunlight by the grapevine canopy. Slope of the land will determine if a different row direction is required to avoid erosion problems.
Rows range in length from 300-1000 feet generally. Within rows, spacing varies from 8 feet for bunch grape verities to 12-20 feet for muscadines. The widest spacing, 20 feet, is recommended only for production of muscadines on the heavier soils of north Florida. Between row spacing of bunch grapes is optimum at 10 feet, the range being 8-12 feet. With single wire trellis systems, 12 feet between rows does little to improve air flow and is wasteful of land, but may better accommodate available tractors and machinery. If trellis with crossarms is used, 12 feet between rows is recommended due to the extension of crossarms into row middles. Spacing at the end of the rows requires about 30 feet of anchoring of end posts and machinery to turn around.
Line posts should be placed between end posts to support the wire and should be equidistant from vines, with a maximum of 3 vines between posts in the row.
Irrigation systems should be designed prior to vineyard establishment to ensure efficiency and expandability.
Trellis Systems in vineyards consist of a series of posts strung with wires to which individual vine stakes and crossarms are attached. The purpose of the trellis is to prevent wind drift of stakes and to support the grapevine canopy. Thus the leaves and fruit are kept off the ground and vine growth is directed along the row so that machinery can easily operate the vineyard. Trellising the grapevine canopy also enhances air flow and sunlight exposure of leaves and fruit, thus improving yields and quality of the grapes.
Choice of a particular trellis system depends primarily on the market destination of the fruit. Grapes grown for wine or juice require a trellis type which will accommodate harvesting machinery.
A single wire trellis or a double wire system with flexible crossarms is recommended for harvesters which operate over-the-row. Wire should be placed at 5-6 feet above ground.
Fresh market grapes, including picking-your-own, must be harvested by hand. Thus the trellis should be designed to provide easy access to fruit. A single wire as five feet provides a comfortable picking height for most people. In pick-your-own operations, a second, lower wire on the trellis (called a vertical two wire system) should be avoided as customers do not like to reach down to pick fruit.
Double wire trellis with crossarms (which need not be flexible) is also suitable for muscadines which are hand harvested. Bunch grapes, however, are not easily picked by hand with this type of trellis due to the different growth habit of the vines.
Selection of Vineyard Materials
Trellis systems components include end posts, line posts, and stakes for individual vines, wire and in some cases, crossarms. All material made of wood must be properly treated in order to be long lasting. Pressure treated pine is recommended as it will last up to 20 years despite the heavy decay index of Florida's environment. Wood should be treated with chromated copper arsenate or a similar water-borne salt. Oil treatments such as creosote and petroleum are not recommended as the woods is unpleasant to handle and can be toxic to vines.
Components of the Trellis
Dimensions for trellis components are given here as guidelines; length of end posts, line posts and stakes will vary depending on height of the trellis wire.
Minimum depth of end posts in the ground is 2 ½ - 3 feet, whereas line posts are placed 1 ½ - 2 feet below ground. Vine stakes should be set 6-9 inches below ground. The minimum diameter for end posts is five inches for multiple wire trellis, four inches for single wire. Line posts should be three inches in diameter. Stakes, which are generally sawn, should be one by two inches. Stakes made of metal or half-inch PVC piping can also be used, the latter being cheaper but less sturdy. Wire should be No. 9, smooth, galvanized. Crimped wire, which does not require annual tightening, may be used but is more expensive.
The trellis row is secured with an end structure, such as a cement block (called the “dead man”). This is wrapped with wire and placed three feet below ground. The wire is then wrapped to the end post. Other systems involve braced end posts.
Irrigation is mandatory in Florida for establishment of a vineyard. Micro-irrigation is recommended with drip being suitable for the soil types found in north and west Florida. In central Florida where sandy soils predominate, spray jets are necessary in order to distribute water uniformly on the soil surface and to plant roots.
Irrigation tubing can be attached to a wire at about three feet above ground for either drip or sprinkler types. This provides clearance for necessary cultivation and herbicide application. It also keeps rodents off the tubing and reduces clogging. Tubing laid directly on the ground is often used for staked micro-sprinklers. Emitter nozzles should deliver water in a 360 degree pattern. Emitters are spaced I the row to provide through water coverage over the vineyard floor.
Establishing the Vineyard Site
Construction of the trellis and installation of irrigation should be completed prior to planting. A diagram of the vineyard layout and design of the irrigation system should be developed before any work is done in the field.
Once the site has been cleared and disced, a base line should first be established using the 3-4-5 rule. This will become the first row of vines. The remaining rows are then marked out, with wooden stakes placed where end posts are to be located. These must be accurately as the line for the row will be established by running a taut string between end posts. End posts should be canted 20 degrees outward from the trellis row (this will allow the end posts to reach an upright position gradually due to tightening of wired each year). Line posts are then placed using the string as a guide. Finally, wooden stakes are placed to mark the planting holes for grapevines. Once the irrigation has been installed and tested, you will be ready to plant Florida's next vineyard.