Growing a Kiwi Vine
A kiwi is a sweet, edible fruit produced by a kiwi vine. Kiwi vines are grown worldwide and have been cultivated by humans for thousands of years. Fuzzy kiwi (Actinidia deliciosa) are grown in warmer climates with a long growing season, while hardy kiwi (Actinidia arguta and Actinidia kolomikta) are grown primarily in cooler climates and maritime regions with cooler summers and shorter growing seasons. There are several varieties of each type of kiwi, so it is important to choose one that is right for your area.
Choosing a Variety
Kiwi vines are generally separated into 2 categories: fuzzy kiwi and hardy kiwi. Fuzzy kiwi varieties grow hairy thicker vines and larger fruit, with a thick fuzzy skin. Fuzzy kiwi varieties typically prefer warmer areas with longer growing periods. Hardy kiwi varieties grow thinner vines and berry sized fruit, with a thin edible skin. Hardy kiwi varieties typically ripen earlier than fuzzy kiwi, so perform better in cooler maritime environments and will ripen fully even in shorter growing periods.
Fuzzy kiwi (A, deliciosa) and hardy A. arguta vines grow to 20’or more annually, hardy A. kolomikta are about 1/2 as vigorous. Kiwi are typically trained on a sturdy trellis with 4-5 wires on a 4’ wide T shaped trellis. Space vigorous fuzzy and arguta female kiwis about 20’ apart, males 10’ apart. Kolomikta females are given 10’, and their males 5’.
Kiwi are not self-fertile and require a male as a pollenizer, at a ratio of up to 8 females per male to produce fruit. Fuzzy and arguta kiwi may cross pollinate in some locations, in others choosing a male of the same species will work better. Kolomikta kiwi flower earlier and do not cross with the other two.
The pollenizers should be planted no further than pollen carrying bees will fly, with no line of sight obstruction, to ensure proper cross-pollination. That distance varies with different bees, 100’ should be a good average distance. If you are growing several females position the male in the middle, rather than at an end.
Fruit ripen late summer to late fall, depending on variety and location.
USDA Hardiness Zone
Fuzzy kiwi are hardy to USDA zones 7-9 and need a long very warm summer to ripen fruit. A. arguta kiwi are hardy to USDA zones 5-9 and their fruit ripen earlier and with less heat then fuzzys. A. kolomikta kiwi are hardy to USDA zones 3-9 and ripen the earliest, late August at Raintree Nursery. This rating tells you the minimum winter temperature the plants typically survive when properly hardened off. We do not have a good rating system at this time for summer patterns (long, short, hot, cool, humid, dry…), but if known, individual descriptions will indicate if a particular plant tolerates (or requires) hot or cool, long or short summers. On our web site you will find a USDA Hardiness Maps (select Growers Information at the bottom of the page) which provides information on the average minimum winter temperature in your location, by zip code.
Many plants native to locations that have cold winters have a Chill Hour requirement to ensure uniform waking up of flower and leaf buds in the spring. The chill hour requirement of plants varies by species, by cultivar, and sometimes by the level of dormancy achieved. If you live in a location in which winter temperatures seldom go below 40°F, and/or winters are short, you may need to select “low chill” cultivars of plants not considered tropical or sub-tropical (apple, pear, or plum for example). Ask at your local co-operative extension service to determine your usual accumulated Chill Hours. View our Chill Hours Chart for more explanation, a chart of typical winter chill hours, and a list of fruits and their typical chill requirements.Kiwi chill hour requirements vary by species and growing location, ranging from a few hundred for fuzzy to 800 for A. arguta and A. kolomikta.
Where to Plant Your Tree
Kiwi need to be planted where they receive at least 8 hours of direct sunlight measured in early summer (late June to early August) for best fruit production. Heat sensitive A. kolomikta will sunburn in longer full sun locations where summers are hot and dry. Sufficient sun exposure triggers the initiation of new flower buds for the next growing season, without which there will be no fruit. Fruit ripening and flavor development are also benefited by the carbohydrate production stimulated by the sun, as well as it’s heat.
Kiwi prefer well drained yet moist soils that are moderately rich with a pH around 6.3-6.8. Improve your soil where you intend to plant by mixing an inch or two of plant based organic matter (manures are best for vegetable gardens), peat, or coconut coir into an area 1 1/2 to 2 times the diameter of the needed planting hole and up to a foot deep. A 2-4” deep layer of mulch (straw, leaves, or wood chips) applied after planting will continue to improve the soil.
Allow sufficient space for both the top of the tree and it’s roots when selecting the planting location. Refer to size descriptions for each variety, keeping in mind these are generally managed or pruned sizes, not maximum potential sizes. If you are planting an orchard be sure to include enough space between rows for transporting supplies in and fruit out.
Growing in Containers
To grow kiwi in a pot you need a final container size of at least 20 gallons, bigger if you are growing the more vigorous fuzzy or A. arguta kiwi. Provide a trellis to support the vines. Plants will grow larger in a larger container, but make sure you have the ability and tools to move the pots heavy weight. It is important for the establishment of the root system to gradually increase the size of the container over several years, rather than go from small directly to very large.
Do not use soil from your garden in the pot, instead use a potting soil mix with some added compost. For larger pots use a potting mix that has larger particles in addition to the smaller.
Care and Maintenance
Watering Your Tree
This is the most important and often the most difficult part of successfully growing plants. There are many factors, including the humidity, temperature, soil type, wind, and amount of direct sun that affect how much and how often water should be applied.
A general rule of thumb for plants in the ground is to ensure they receive an inch of water per week over the root zone. An inch of water is equivalent to about ¾ to one gallon per square foot of soil surface area. The typical three foot diameter planting hole would need 7 ½ to 10 gallons of water per week provided by rainfall or by the gardener.
Apply this water once a week, two times per week if soil is fast draining. This will of course depend on your own conditions and the plants you are growing! DO NOT water lightly each day because this results in a wet surface and dry root zone area. The soil should be moist but not soggy to a depth of about a foot for most growing plants. The top inch or two can feel dry, and the plant still be well watered. The trick is to have the water available where the roots are. In hotter and sunnier areas, a mulch of straw, bark, etc. can greatly ease the burden of summer watering. For plants in containers, water until the soil is saturated and water comes out of the drainage holes. Let the container dry until the soil is dry to the touch 1-2 inches down (more deep with deeper pots) and the container is lighter in weight. A plant that has wilted can be receiving either too much or too little water.
In rainy areas like the Pacific Northwest most of the plants that we offer will need relatively little supplemental irrigation ONCE THEY ARE WELL ESTABLISHED in the ground and have had a chance to develop a good root system. However even here it is important to make sure plants have regular, deep watering during the first couple of growing seasons, and the first summer is especially critical. In drier areas, or where soils do not retain water well, permanent irrigation is essential. Remember that you don’t want your trees to just survive, but rather to thrive. Make sure they get the water where they need it, starting at the drip line and extending away from the tree up to several feet ( for older trees) where the feeder roots will be. Drip irrigation and soaker hoses can be an efficient way to deliver the water.
For good steady growth and high productivity, your trees need to have adequate amounts of various mineral nutrients. Some people are fortunate and have naturally rich fertile soil. Many soils, however, are deficient in some nutrient or another and use of fertilizers, organic or chemical, can be highly beneficial if you want your trees to grow well. If you have a large garden or orchard it can be well worth it to have your soil analyzed by a qualified laboratory so you know for sure just what your soil needs. Typically this might cost $30-$60, depending on how detailed an analysis you want. Unless you know what is available in your soil, you will not be able to supplement it properly.
Use an all-purpose or balanced fertilizer like the organic fruit tree and shrub fertilizer. A couple of inches of well-rotted compost on the root zone can also be an effective fertilizer. A generous leaf or straw mulch around your trees will not only conserve moisture and help in weed control, but also keeps your soil healthy by building up humus, attracting earthworms, and supporting beneficial fungal organisms. This encourages young trees to be strong, healthy and productive. Use of concentrated products like chemical fertilizers or strong organics (for instance blood meal) is usually done from late winter through early summer. Applying fertilizer after early summer can encourage lots of soft new growth that is much more likely to be damaged by winter cold. Excessive use of fertilizer can in-crease disease problems on your plants and can even kill them. Use of too much fertilizer, whether chemical or organic, can contribute to stream and groundwater pollution, so please try not to use more than your trees really need. As a general guide, if your tree is producing about one foot of new growth or more a year and has healthy looking foliage, it may not need much or any fertilizer.
Pests and Diseases
Find out what insects and diseases are typical in your area. Ask your local co-operative extension professional what the typical insect and disease issues are in your area. Then you can make selections based on resistance or tolerance information available in our catalog, or, make a plan for controlling problems you can expect with the susceptible varieties you prefer to grow. If you see resistance information about a particular disease for one variety but not another of the same kind of fruit, then that variety may be susceptible or might not have been tested so is unknown. The following are some of the more common issues.
Browsed shortened branches. Leaves are obviously munched on or plants are pulled up.
Fences or cages at least 8’ tall. Plastic mesh, electric, or woven wire fences.
At Raintree, an 8’ woven wire deer fence has worked best. Repellents don’t work consistently. and only trained large dogs patrolling the perimeter are effective. Some have had success with the product “Deerchaser.”
Fruits disappear or have gaping holes in them. Strawberries, blueberries, cherries and filberts are most susceptible but most fruits suffer occasionally.
Reflective Bird Scare Tape can work well. Bird netting. Cages.
Blue Jays start harvesting filberts when ready to pick, and so should you. Nuts dropped by jays are usually empty.
Bark eaten in a band from soil level up to 8” and roots eaten too, usually in snowy areas with lots of mulch or tall grass at base of trees.
Keep mulch 4”-6” away from trunk. Keep grass short and 1’-2’ from trunk. Use vinyl tree guard wrapped around trunk until tree well-established.
Voles and mice will chew a couple inches above ground and also into the root system. Rabbits will chew up to 8” high, particularly apple trees.
Leaves stippled, very small crawling insects on the underside of leaves. Webbing often also present on underside of leaves or surrounding new shoot tips.
May develop resistance to Pyrethrin/ rotenone spray. Release predatory mites. Insecticidal soap with ultra-light oil. Usually not a problem if pesticides are kept to a minimum.
Mites thrive during hot dry weather.
1/32 to 1/8” long pear shaped insects that multiply rapidly, espe- cially on the underside of leaves and on stems. Can be pink, green, black or white. Leaves show red blisters or are curled-down and stems turn black with sooty mold.
Natural predators like lady bugs and parasitic wasps often provide control. Knock aphids off with water spray. Spray with Pyrethrin, Rotenone, Insecticidal Soap, or delayed dormant oil. Control ants if they are also present.
Trees can tolerate some infestation. Monitor in late spring and summer. Control is more important on new trees. Grow plants that attract predators, i.e. dill or yarrow.
Spotted Wing Drosophila
Eggs are deposited 7-10 days prior to fruit ripening; holes in fruit, spotty molding, larvae in fruit, exuding berry sap, scarring.
Monitor with traps. Spinosyn based insecticides. Sanitation: In fall, adults feed on over ripe or split fruit (both vegetable and tree fruit) to prepare for winter.
Go to https://agsci.oregonstate.edu/spotted-wing-drosophila/what-backyard-fruit-growers-need-know-about-swd-drosophila-suzukii-fly-pest for current information, or check with your local co-operative extension office.
Numerous ants scurrying up and down the tree trunk; aphids, scale or mealybug present in large numbers, lots of sticky honeydew, perhaps sooty mold.
Find hill and apply pesticide. Apply Tangle Trap over 2-3” wide band of paper wrapped around trunk. Eliminate other pathways into tree.
Ants nurture and protect these insects in exchange for their sugary secretions. Insects may be difficult to control until the ants are controlled.
Brown Marmorated Stink Bug
Poking-type feeding damage followed by decay on fruits, nuts, berries and leaves. Deformity in the healthy tissue surrounding the dead tissue. Brown spots can show up in stored fruit.
Monitor with traps, some broad spectrum pesticides may work. Researchers are working on finding effective controls, but no info has been released yet.
BMSB over winters in groups in dry protected areas, such as houses. If you find them on or in your home use the vacuum, squishing releases their defensive stink. See stopbmsb.org for more info. Feeding begins in spring when the weather warms up and continues until new adults go dormant for winter.