Climate

Kiwifruit requires a long growing season-from 225 to 240 frost-free days. It grows well in most citrus and peach areas of California, including southern California and the San Joaquin and Sacramento valleys. In southern California, the lack of winter chilling may cause dormancy problems and low fruit yields if the standard market variety is grown.

Although winter hardy to 15°F when fully dormant, young shoots, flower buds, and flowers are vulnerable to frost injury. As little as 30 minutes time at 30°F will damage these sensitive parts. In spring, such injuries ruin fall crops by damaging the developing flower buds.

Breezes of 10 to 15 miles per hour or strong gusts can break developing shoots and reduce vine growth and production. Hot, dry air can wilt vines, scar fruit and leaves, and cause fruit to drop. Vines grow and produce best in areas sheltered from constant or gusty winds.

Pollination Requirements

Kiwifruit vines are either male (bearing only male flowers) or female (bearing female flowers and fruit). The transfer of pollen from male to female flowers is essential for fruit production. One male vine may supply enough pollen for four females.

Fruit size correlates with the number of seeds, and this in turn depends on adequate pollination. Large fruits should contain from 1,000 to 1,400 seeds; small, unmarketable fruits may have no more than 50 to 100 seeds. Pollinators include bees and other insects.

Bees do not frequent all areas, so the home gardener may have to hand pollinate to guarantee large fruits. If you hand pollinate, remember that female flowers are viable and receptive to male pollen up until 9 days after opening. Male flowers have viable pollen for only 3 days after opening. To hand pollinate, simply pick a freshly opened male flower and rub it against a viable female flower for a second or two. You can use one male flower to pollinate as many as five female flowers before discarding it.

Soils

Kiwifruit can be grown on a wide range of well-drained soils that are at least 4 feet deep. Slightly acidic to neutral soils (pH 5.0 to 7.0) are best. Excess salts in water or soil can cause leaf burn. Alkaline soils (pH greater than 7.0) may cause inter veinal chlorosis of younger leaves.

Water

To establish kiwifruit, you need good soil drainage and an adequate supply of water. Watering is one of the keys to growing kiwifruit, and backyard gardeners have lost many plants to inadequate watering. Insufficient water, particularly during phases of rapid growth, results in wilting and the sudden appearance of burned or brown-charred leaves. These patches may enlarge to cover much of the leaf. As the affected tissue dries, the edges of the leaf may roll up.

Once you have planted the vines, do not stress them by applying too little water. In hot weather, water three to four times a week for vines 3 years old or younger, and twice a week for older vines. Water deeply, but do not flood. Flooding will increase the chance of root infection by soil pathogens. You may use a hose, a drip system, or mini-sprinklers to irrigate.

Installing a drip system will save you money on your water bill. The system applies water slowly and directly to the vines, resulting in reduced evaporation and less runoff. Modern systems, if left undamaged, are self- cleaning, self-flushing, and affordable. If you use a drip system, place a 1-gallon-per-hour emitter about 1 foot from the plant at the time of planting. During the second year, put an emitter on each side of the plant, about 15 to 18 inches from the plant. When the plant is 4 years old, add two more emitters 3 feet from the previous two. In hot weather, water the vines every day or every other day. When the plants reach maturity, shift to mini-sprinkler irrigation because it is hard to wet enough soil for maximum yield and plant growth with only four emitters per vine.

A mini-sprinkler is a small plastic sprinkler that throws a fine spray of water through a fixed or rotating head. The water sprays in a circular pattern 6 to 18 feet in diameter. Full- and partial-circle patterns are available. Generally, you should run mini-sprinklers for 4, 6, or 8 hours two to four times a week. They wet more soil than a drip system, are easy to install, can be used to replace drip systems, and plug up less frequently than the older drip emitters did.