Training

Young kiwifruit vines must be trellised if they are to be manageable when mature. By erecting the right structure for plant growth, you will ensure easier access to the vines through years of production. Of equal importance is careful pruning to promote better fruit buds, allow good fruit size, reduce shade, and encourage better air circulation.

Support

Kiwifruit vines need the support of a T-shaped trellis, single-wire trellis, arbor, patio cover, or pergola. Build the support system before you plant the vines. Kiwifruit vines are vigorous growers, and any delay in training them will make it difficult later to establish the desired structure. Whichever support system you select, build it from sturdy materials to support the hundreds of pounds of fruit and vine your plant will produce. Because kiwifruit plant life can exceed 50 years, build the trellis right the first time.

Train kiwifruit vines with a T-shaped trellis because it allows easier pruning than other structures.

The pergola system, the other major trellis technique for kiwifruit, is used mostly by commercial producers. A pergola is much harder to build than a T-shaped trellis, and vines on a pergola are usually harder to prune. Pergola training will not adapt to most home gardening sites.

T-shaped trellis. To build a T-shaped trellis to support two plants, you will need three pressure-treated posts that are 4 inches in diameter and 8 to 9 feet long. About 6 inches from the top of each post, attach a 2" x 6" x 6' cross-arm. Place these assembled T-bars 15 to 20 feet apart. The trellis should be 5 to 6 feet tall and anchored to prevent its collapsing under the weight of a fruiting vine. For longer life, you may want to tar or water seal the buried portion of the posts.

The ideal trellis length for two plants is between 30 and 40 feet. Connect the T-bars with three to five equally spaced lines of #12 or #13 gauge galvanized steel wire. Do not overstrain the wires; they may loose elasticity and become weakened. Establish additional support structures for additional vines or growing space. Follow the spacing guidelines for a T-shaped trellis given above.

Single-wire trellis. An alternative system, the single-wire trellis, uses only one wire between the posts and no cross-arms. A second wire is sometimes added 12 to 20 inches below the first, and is used to stabilize the vines in windy weather. This trellis, although simpler to construct, is harder to maintain, and pruning the vine is generally more difficult. The single-wire method can be a space saver, since it is well suited to plantings against walls or along fences. Fruiting canes are allowed to grow vertically and are pruned accordingly.

A kiwifruit vine trained to an arbor or patio cover is planted at one end of the structure and pruned to maintain a single cordon 5 to 6 feet above the graft. The vine has one less cordon than in other methods, but its establishment and pruning are essentially the same.

Establishing the vine
In the first 3 years of plant growth, concentrate on establishing the vine on the trellis to provide a manage- able structure for later pruning and harvesting.

For each vine you plant, select a strong-growing shoot above the graft as its main trunk. Drive a light stake as tall as the trellis into the ground beside the selected trunk. Attach the stake to the center wire of the trellis. Tie the trunk loosely to the stake at intervals of about 1 foot to provide support and prevent damage to the vine. As the trunk grows, head back any side shoots and remove rootstock growth to force top growth. Allow the trunk to grow as far as it will above the wire, but then cut it back to the wire in the dormant season.

By cutting the trunk back to the wire, you will force development of several new side shoots. From among these shoots, select the two permanent arms (cordons) that will grow along the center wire on either side of the trunk. These cordons and the trunk form the basic structure of the plant. During spring and summer much growth will emerge from the cordon. Cut growth back to near the cordons the following winter. If a cordon's growth should cease or if the growing tip should curl around the wire, cut out the non growing or curled shoot. A stronger nearby bud will then develop and continue the growth of a continuous cordon.

If the trunk fails to reach the wire in the first year, cut it back when dormant, leaving four to eight buds above the graft. In the second year, select the strongest shoot and retain it to serve as the replacement trunk.

During the second winter, remove excess growth and select healthy buds emerging 10 to 15 inches apart along the cordons. Remove excess buds by rubbing them against the cordons with your fingers. Cut the cordons back to the eight or twelve buds closest to the trunk. These buds should produce your first temporary fruiting canes. Train the end bud of the cordon so it will extend the cordon further along the trellis. Allow the fruiting canes to develop at right angles along both sides of each cordon, and cut the fruiting canes back just outside the outer wires. Do not train a fruiting cane to grow along the outer wire. Such growth can adversely affect vine performance and management.

During the third winter, select buds emerging from new growth of cordon. Cut the cordon back to eight or twelve new buds on the growth of the previous spring and summer to force more fruiting canes the following spring. During the fourth spring and summer growing season, remove the stake you used to establish the trunk. That spring, laterals emerging from the previous year's fruiting canes will produce flowers at the axils of the first three to six leaves closest to the fruiting canes. Those flowers will provide the first harvest of kiwifruit that fall. By the end of the fourth spring and summer's growth, the framework should be well established.

Prune the vegetative and rootstock growth occasionally throughout the growing season. In general, the most productive canes are those that have grown in full sunlight, with short internodes, closest to the trunk.

Pruning female vines
Beginning with the fourth winter, female vines will require annual pruning to renew the fruiting wood, control vegetative growth, and provide fruit of superior quality and size. Do most of your pruning in the winter, before the end of January. Summer pruning, usually restricted to controlling vigorous upright sucker growth, is done in June or July. Throughout the growing season, unwrap and cut off tendrils that have twisted around branches. Do this regularly to prevent them from strangling branches.

Begin your winter pruning by removing dead or injured growth. Remove shoots or suckers growing from the trunk. Cut out all crossing, twisted, tangled, or broken canes. Remove any growth that approaches the ground.

Kiwifruit are produced on the current season's growth, originating from 1-year-old canes that have already grown through one full summer. To renew fruiting canes, remove the older (second season) canes that have already fruited. Usually, the new fruiting canes will have developed from buds at the bases of these older canes. These canes will bear fruit the next spring/summer. Repeat the process of removing 1-year-old fruiting canes each winter. During the grow- ing season, a mature vine should have 30 to 40 healthy fruiting canes, half of which will bear fruit that season, the other half, emerging from the base of the latter, will bear fruit the following season.

Pruning male vines
A non fruiting male vine should have the same basic structure as a female vine. Do the major pruning on male vines immediately after flowering and pollination, usually in June. Pruning after bloom restricts male plant size and maintains good annual flowering canes. To prune, cut the male vines back to 2 or 3 feet from the cordons, leaving only a few canes spread on the trellis. Whitewash cordons in warmer climates to prevent sunburn injury. Winter pruning of male vines involves removing twisted, dead, and weak canes to encourage new growth from 1-year-old growth near the cordon.