|Fruit of mixed cultivars of kiwis at the Teltane Farm booth at the Common Ground Country Fair. Hardy kiwis are not difficult to grow and can be very productive. English photo.|
by Tom Vigue
If you think kiwis are all brown, fuzzy and can be grown only in New Zealand or California, think again. Although Actinidia deliciosa, the kiwi of commerce, is hardy only to 10° F, the more than 50 species within the genus Actinidia include many that are hardy to -30° F and some even to -40°. Actinidia arguta, the species most commonly referred to as hardy kiwi, is zone 4 hardy and includes many cultivars that produce delectable fruit. Almost everyone who tastes this species says it’s more delectable than the fuzzy kiwi, being sweeter but otherwise similar.
Hardy kiwis have smooth, green, edible skin and, at about the size of a large grape, can be eaten whole, no preparation needed. Besides A. arguta, we’ve had some experience with A. kolomitka, hardy to zone 3.
Origins and History
Native to the Russian Far East, China, Japan and Korea, fruit of Actinidia species has been used by humans for many centuries. During the late 19th and early 20th centuries, western fruit explorers first brought samples of the genus to North America. For many decades the plants were regarded only as an ornamental, sometimes called bowerberry or taravine, and were used to grace arbors, archways and the like. They were planted in arboretums and on the grounds of numerous estates, public buildings and college campuses, where the now ancient vines can still be found sometimes. We now derive many of the cultivars we depend upon for fruit production from these old plantings. Ancient plants may be propagated by rooting hardwood (dormant season) cuttings, or softwood (early summer) cuttings. Also, unpruned kiwi vines often reach to the ground and self-layer, producing new plants that can be transplanted.
Vigorous, Dioecious Plants
Kiwi plants are very vigorous, twining vines, rampantly clambering over anything they can twine around. In their native habitat they often climb trees to heights of 100 feet or more. In cultivation they can be confined, with attention to pruning, to a trellis, fence, pergola or arbor. Such structures need to be very sturdy, since these plants can become considerably heavier than, for example, grapes. Mature, healthy plants can grow numerous new, 6- to 12-foot canes annually, creating a phenomenal transformation by July. Where neatly pruned plants grew two months before, now enormously long canes grow in every direction.
Kiwis are dioecious; that is, there are separate male and female plants. One male can pollinate up to eight females if planted in an appropriate configuration. For example, setting a male plant in the center of three rows of three plants each will place the male essentially adjacent to each of the eight females. If grown on a fence, a male between two females works well.
The faintly rose-scented flowers, though not particularly showy, are pollinated by bees and other nectar-feeding insects. In zone 4, flowering generally occurs around the summer solstice. Expect arguta plants to begin flowering in their fourth or fifth year.
Mature arguta plants, around seven years old, can bear enormous crops. Our ‘Michigan State’ variety now occupies 30 feet of linear trellis and bore 80 pounds in 2008. Plants of A. kolomitka, though much smaller in stature and bearing smaller fruit, are very precocious, routinely flowering in their second year.
Planting, Spacing and Supporting
Kiwi plants prefer a deep, well-drained soil. (Of course. What doesn’t?) They are very sensitive to standing water, particularly after spring growth begins. Three or more days of standing in waterlogged soil after bud break can severely damage root systems, so avoid such spots. Otherwise these plants are quite adaptable, growing in many soil types and tolerating a pH from about 5.5 to about 6.5.
Although kiwis are as hardy as mentioned above, young plants (especially males) are somewhat more sensitive during the first couple of winters. A protective wrapping of burlap or other material is definitely beneficial, if not essential. Even a little protection from the sharp cold and wind helps. Growing the plants in containers the first season or two can be effective, but don’t let the plants become pot-bound. Kiwis never recover from this, surviving season after season as tiny, dwarf plants, never taking off. After the first season or two, kiwi plants are very rugged and can withstand anything our changing climate can throw at them.
|A guy wire and tensioner. Photo by Tom Vigue.|
The most commonly recommended spacing for kiwis is about 16 feet between plants and 8 to 16 feet between rows. An 8-foot row spacing is great for pollination and is not so close as to inhibit growth due to crowding, but each season’s growth can easily reach from row to row. This is not a problem with annual pruning, but skipping a season of pruning will result in quite a tangle. A 16-foot spacing between plants works very well. Six feet is an absolute minimum and is only recommended if you have limited space. In very fertile soil, a plant can productively occupy as much as 30 linear feet of trellis. Beyond a 30-foot spread, the root system cannot support much fruit.
Commercial kiwi trellises are usually T-bars, 6 feet high with a 6-foot cross bar, but numerous other possibilities exist. Be creative. My system uses stop-sign posts, which can be purchased new from companies that supply the highway department and can sometimes be found used at metal recycling yards. The latter are usually bent, but straight pieces that are long enough for our purposes can usually be salvaged.
|A guy wire, showing the tensioner being tightened with a crank. Photo by Tom Vigue.|
I use a heavy bar to make a pilot hole in the ground. Into this, using a sledgehammer, I drive a 3-foot piece of post, leaving about 6 inches protruding. Onto this I bolt a 6-foot piece. This method precludes the need to drive a 9-foot post into the ground, which, without special equipment, requires a ladder and a few extra people to steady everything, most of whom end up getting hurt. In our rocky, glacial till, driving in a 3-foot piece is about all we can manage. If you have deeper, softer ground, you might want a 4-footer.
My posts are spaced 16 feet apart, as are my plants. Galvanized, high-tensile, 12-gauge wire supports the vines between posts. I add an extra post 8 feet from the ends of rows. Then, 8 feet beyond that, I drive a 4-foot piece at a 45-degree angle. To this angled piece I attach a guy wire that includes a fence wire tensioner to keep the whole thing taut and allows me to tighten the structure if it begins to sag with the increasing plant and fruit weight.
|A guy wire around a cable thimble. Photo by Tom Vigue.|
My plants are a couple of feet from the posts, within the rows. At the top of each post, a foot-long, wooden crossbar with a V-notch in it supports the trunks of the plants, eliminating the need for tying.
A caveat about stop-sign posts: the holes in them are convenient for running wires through and attaching wires at the ends of runs, but they have sharp edges that can eventually cut through 12-gauge wire, particularly during ice storms. To prevent this, where a wire runs straight through a hole, first insert a plastic wall anchor (available at hardware stores) in the hole. (Make sure it is a size that fits tightly.) Where wire wraps around, as at the ends of the structure, use a cable thimble or an eyebolt to create a radius, thus eliminating the sharp edges.
The single, 6-foot-high wire is really all you need. Don’t put an extra wire at 3 feet: Canes trained along it are invariably so shaded (kiwi foliage is very dense) that they produce little fruit. With stop-sign posts, adding a 6-foot crossbar and four extra wires to make a T-bar system is possible, but the added expense and materials can be justified only in a commercial vineyard where efficient pruning and harvesting must be considered.
|A kiwi trunk supported by a V-notch, with two large cordons heading left and one heading right. Photo by Tom Vigue.|
Training and Pruning
Train single (or a few, but never many) arms along the wires. These will be permanent cordons that will grow many canes.
Allowing canes to remain long only encourages them to grow longer yet; so to encourage fruit production, prune the canes. Kiwis fruit on new canes and on old wood. On new canes growing from the previous season’s buds, flowers are produced along the basal couple of feet. So, during the late dormant season (late March/early April in zone 4), remove any canes that are closer than about 8 to 12 inches apart (to prevent overcrowding) and head back remaining canes to about 2 feet long, which will stimulate the generation of many new canes. The basal portions of all these new canes will be very fruitful. For subsequent seasons, canes that have already fruited can be removed, and new canes can be headed back.
|Spurs. Photo by Tom Vigue.|
On older wood along the cordons and around the bases of canes, fruiting spurs from a few inches to a foot or more in length will grow. These spurs are not long-lived like apple tree spurs, but they do live for several seasons and are very fruitful. Remove them only after they die.
Canes will grow long and straight until they encounter something, whereupon they begin to twine. Canes tightly twined around each other or around the wire will girdle and die. When choosing cordons, select relatively straight canes and give them only a few turns around the wire for support. Thereafter, always prune off tightly twined canes.
If all this training, pruning and attention to detail doesn’t appeal to you or seems daunting or is simply more effort than you want to exert, but you still would like to have some kiwis, you can certainly introduce plants into the landscape and let them be wild, as Warren Balgooyen has done at his Norridgewock farm (see photo). Or, as Tom Griffin of Hope’s Edge Farm in Hope did (see photo), give them a structure (or fence or whatever) and let them do what kiwis do best: ramble. They will still produce plenty of fruit, and harvesting it will put you in close touch with our hunter-gatherer ancestors. These wild or semi-wild plants can also be a source of propagation material for tamer plantings.
Harvest date varies among cultivars and from season to season. Fruit of any given cultivar tends to ripen over about two weeks. In general, in early to mid-September, begin checking the fruit every few days to see if any are softening. As soon as 2% or so are soft (ignore fruit that are damaged, misshapen, particularly small or extremely heavily shaded, as these tend to soften somewhat prematurely), assume that the rest are mature enough to harvest. At this point, with most fruits still rock hard, strip the entire crop off the plants.
Firm fruit may be stored at refrigerator temperature for up to eight weeks, or perhaps longer. When placed at room temperature, they will ripen to perfection within a few days, so you can remove them from cold storage as desired. Properly ripened fruit will yield to light pressure between thumb and finger, will still have opaque skin, and will be indescribably sweet and delicious. When the skins begin to be translucent, they are starting to go by. These deteriorating fruit are still edible, but they lose flavor and their texture becomes less appealing. Even in cold storage, fruits will gradually ripen to perfection. If you have more than you can eat fresh, they make wonderful jam, preserves and juice, and frozen puree (skins removed with a food mill) is very useful.
Cultivars Proven in Maine
- ‘Michigan State’ – Largest fruit among argutas. Shaped rather like a thumb. Luscious and delectable. Originated at Michigan State University.
- ‘Meader Female’ – Oval fruit. Very productive. Absolutely delicious. Selected from many seedlings by the late Professor Elwyn Meader.
- 74-8 – Selected by USDA. Shaped like a truncated cone, wide at stem end, tapering to blossom end. Green with slightly reddish core. Very sweet.
- ‘Geneva 2’ and ‘Geneva 3’ – From Geneva, N.Y., Agricultural Experiment Station. Shaped like 74-8. Green throughout. Very sweet.
- ‘Ananasnaya’ – Purportedly a cross of arguta and kolomitka. Extremely hardy. Very heavy crops. Russian name means “pineapple-like,” and the taste is slightly so, being both tangy and sweet. Skin is a beautiful rusty red color. Latest ripening, very end of September/beginning of October.
- ‘Longwood’ – From Longwood Gardens, Pennsylvania. Reliably hardy.
- Males: ‘Meader Male’ and ‘Smith 2’ are proven zone 4 hardy and provide a profusion of pollen.
- ‘Krupnoplodnaya’ – Russian name means “large fruit.” Largest of the kolomitkas, but still much smaller than arguta fruit. These are long and slender, like half of your pinky. Sweet, good. Ripe in mid-August.
- Males: Any male kolomitka should be fine. Males of this species have variegated pink, white and green foliage and make a lovely ornamental. Sometimes sold under the name ‘Arctic Beauty.’
Numerous other A. arguta and A. kolomitka cultivars are worthy of trial.
Fedco Trees, P.O. Box 520, Waterville, ME 04903. www.fedcoseeds.com
Tripple Brook Farm, 37 Middle Rd., Southampton, MA 01073. www.tripplebrookfarm.com
One Green World, 28696 S. Cramer Rd., Molalla, OR 97038. www.onegreenworld.com
White Sign, 45 Dempsey Greaves Lane, Stillwater, ME 04489. 1-800-479-6193; www.whitesign.biz (source of stop sign posts)
Kiwifruit Enthusiasts Journal, Vol. 6. 1992. Michael Pilarski, ed.; Friends of the Trees Society, P.O. Box 253, Twisp, WA 98856; (509)997-3809; [email protected]; www.friendsofthetrees.net
Growing Kiwifruit. Pacific Northwest Extension Publication PNW 507, Oregon State University, 2005; extension.oregonstate.edu/catalog/pdf/pnw/pnw507.pdf
Uncommon Fruits Worthy of Attention, by Lee Reich. Addison Wesley, 1992.
About the author: Tom Vigue, his wife, Eileen Fingerman, and daughter, Kira, live a vegan lifestyle at Kiwihill Farm in Sidney, Maine. Their 1/4-acre garden and extensive fruit plantings produce much of the food they consume. Their owner-built, passive solar, stone house keeps them warm in winter, cool in summer.