Growing Hardy and Variegated Kiwi Fruit
There’s fruit, and then there’s tropical fruit. The division seems pretty simple. On one side is the familiar fare, such as apples, pears, and grapes. On the other side are bananas, pomegranates, guavas, and others. No one questions the division; we typically assume we can grow familiar fruit here in the U.S., while tropical fruit will only grow somewhere else, where warm breezes always blow.
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But suppose you could grow a so-called “tropical fruit” right here, in your own backyard? I’m talking about the kiwi fruit — only, not the familiar fuzzy kiwi you find in grocery stores and cut-fruit arrangements. Rather, my topic of discussion is the hardy kiwi (Actinidia arguta) and variegated kiwi (A. kolomikta), sometimes called “arctic kiwi.” Both are vines from the same general region as the kiwifruit (A. deliciosa), growing across China, Mongolia, Korea, and even Siberia. Let’s explore what distinguishes these two types, and how you can help them thrive in your garden.
Know Your Kiwis
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A few differences exist between the hardy kiwi, variegated kiwi, and kiwifruit. The first difference, and arguably the most important, is growing range. Hardy kiwis grow well in Zones 3 through 8, and variegated kiwis thrive in Zones 4 through 8. To be fair, even kiwifruits aren’t exactly tropical; they grow and fruit as far north as Washington, D.C., and across California into the Pacific Northwest (specifically, Zones 8 to 9).
Another difference between kiwifruits and their hardier cousins is the size and skin of the fruit. While kiwifruits are as big as a double-yolked hen’s egg and covered in a soft, brown fuzz, hardy and variegated kiwis are small and smooth-skinned, about as big as a large grape, and able to comfortably sit on a quarter with room to spare. These small fruits are more like a berry, and have that familiar kiwi flavor, only sweeter, often with notes of melon, pineapple, or other tropical flavors, and a satisfying crunch, thanks to the tiny seeds.
The vines grow well in the eastern, middle, and southern parts of the U.S., as long as the proper conditions are supplied. They need early frost protection, windbreaks, good drainage (both air and soil), and solid trellising. A good site is usually halfway up the side of a gentle slope with southern exposure and windbreaks, such as spruce and pine trees, blocking the prevailing winds. The vines need well-drained, slightly acidic soil. Irrigation may be necessary during dry periods, but be careful; waterlogged roots will rot away, killing the vines.
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A quick note on variegated kiwis: They sunburn easily, and are more ornamental than productive, with cream, pink, and green variegated leaves, especially on male vines. They do produce fruit, but far less than hardy kiwis, and tend to drop the fruit quickly after it ripens.
Construct Your Kiwi Vineyard
Plan for a large space when laying out your kiwi arbor. Kiwi plants always seem to need more space than you’d expect. Most publications recommend providing 10 feet of space for each vine, but most growers will tell you the vines will quickly outgrow their allotted space. Plan for 20 to 30 feet between vines in a row, with 15 to 20 feet of space between rows. Fortunately, hardy kiwis are so productive that you won’t need more than two or three vines to supply your family with all the kiwi berries they can eat.
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Kiwi vines can be either male or female; the female vines produce fruit, but only if there’s a male vine available for pollination. Most kiwi suppliers will carry both hardy and variegated female varieties and male companions. Kiwis can be pollinated by wind or by native bees. If you rely on wind pollination, position your male vine upwind of your female vine, or in the middle of a grouping of females. Alternatively, you can graft male branches onto a female vine; just be sure not to prune them off accidentally. For large plantings, allow one male vine for every six females for good pollination.
Once you have your vineyard laid out, carefully consider your support structures. Like grapes, kiwi vines need something to climb. But, whereas grapes use curling tendrils to cling, kiwis twine around their supports (if you allow them to).
Because kiwis can live for a century or more, the supports must be built to last. Unlike grapes, kiwis grow best on a horizontal, flat surface, such as pergolas and T-bar trellises. Whichever system you choose, build it 6 feet high. This will make harvesting, pruning, and maintenance much easier on your back.
Use 6×6 timbers, either pressure-treated to resist rot or encased in concrete bases. Untreated, unprotected wood won’t survive nearly long enough. Dig deep enough to situate the posts or concrete at least 3 feet in the ground. Concrete bases should be at least 12 inches in diameter, with the posts extending 2 feet into those. Alternatively, if you have access to heavy steel beams or threaded steel pipe, you can make frames from them. If using pipe, select at least 2-inch pipe. Steel fence posts aren’t heavy enough or sturdy enough to support kiwi vines.
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T-bar trellises are set up like a fence or multi-wire clothesline, with posts every 10 to 15 feet. Each post supports a 10-foot crossmember, centered over the post with a knee brace for structural strength. Bolt the components together with galvanized or stainless steel hardware. Connect each crossbar to its neighbor with five strands of 12.5-gauge galvanized wire, spaced out evenly across the crossbars. Each strand should be fitted with a tensioner to maintain high tension. Install a sleeper post, or deadman, at each end of the trellis, with guy wires attached to prevent the end posts from leaning inward.
Caring for Your Kiwis
Plant the young kiwi vines directly beneath the center wire, appropriately spaced from each other. Plant the vines between (not beside) posts to allow room for their trunks to expand and their roots to grow. This will also keep the roots away from the concrete, which can raise the pH of the soil too much for their comfort.
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More space is better, as kiwis are incredibly vigorous growers, putting grapevines to shame. Some cultivars can put out 30 feet or more of growth in a season. Not supplying enough space is a recipe for disaster, promising a nightmare of pruning and fighting the vine to keep it contained.
Provide each young vine with a bamboo cane, or other light stake, for guiding its early growth. Don’t allow the vine to wrap around the stake; the shoot will eventually form a trunk thicker than a split-rail fence post, and needs to be trained straight. Instead, tie it securely to the stake at several points, so it grows straight up toward the wires. Check back regularly — even daily — to tie it up as needed, using soft string, such as cotton twine or cloth strips. Don’t underestimate how fast they can grow. If a vine does get away from you and wraps around the stake or bends away from it, trim it off just above the last bud on vertical wood and start over. It should easily reach the wires in its first year.
Once the vine reaches the wires, trim it back to the bud just under the wires. Allow the top two buds to grow horizontally along the center wire, tying them to the wire as they grow. Don’t wrap them or allow them to twine around the wires. These will become the two main branches of your kiwi vine. As they grow, they’ll send shoots more or less perpendicularly out to the sides. Allow these side shoots to drape over the outer wires in a canopy. They can even grow far enough to hang down to the ground. Feel free to summer prune them lightly, as needed. The vines should achieve their structure in two or three years, and fruit within 5 to 8.
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Prune heavily in late winter when the vines are dormant, typically in late February or early March. Don’t wait too long to prune. Once vines begin to break dormancy, they produce sap heavily, and pruning wounds can bleed excessive amounts of sap, which can weaken the vines. Open up the general structure to allow good airflow and sunlight penetration. Prune out dead wood, weak wood, and poorly placed, congested shoots, and cut back any shoots that produced fruit the previous year, leaving three or four buds to create new shoots. Don’t be afraid to prune hard; they’ll grow back. It’s better to accidentally prune too hard than to prune too little.
Harvest from the Vine
Fertilize kiwi vines in spring and early summer. They welcome a pound of nitrogen each year, especially in the form of compost or composted manures. Feed early, as too much fertilizer late in the year can delay ripening. Maintain shortgrass ground cover or heavy mulch under the vines, and irrigate during dry periods. In summer, prune lightly and regularly to remove poorly placed shoots and thin out overgrown patches. Pruning too heavily can stimulate the vines to regrow heavily.
The vines bloom from late May into early June, bearing delicate, white blossoms about as large as a quarter. The male blossoms only have pollen-bearing stamens, while females have both stamens and pistils. The vines bear fruit late in the season, from August into October. A mature vine can produce up to 200 pounds of fruit in a season.
Kiwis have a high sugar content, and sweeten quickly as they ripen. Commercial growers use Brix Refractometers to determine sugar content, and harvest their crop when the berries reach 7 percent sugar; the percentage can rise to as much as 20 percent later. Rather than investing in an expensive piece of equipment, simply sample a berry every now and then to decide when to pick the crop. They can be picked a bit green and stored in your refrigerator for a month or so.
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Hardy and variegated kiwi have an incredible punch of vitamin C, higher than the equivalent amount of oranges. They also supply antioxidants, potassium, and dietary fiber. Because of these properties, they’re reported to be beneficial for heart health, blood pressure maintenance, improving sleep, and maintaining healthy skin. Plus, they taste great. These kiwis can be eaten fresh, made into jams or fruit leathers, and even baked into pies or pressed for kiwi-apple cider. Too much heat while cooking can destroy the brilliant emerald-green of their flesh, but does little to change their flavor.
If you want a taste of the tropics on your own homestead, or desire to distinguish your market stand from the rest, consider growing kiwis. Give them room, give them company (male vines), build trellises to last, and get ready to harvest lots of sweet, emerald gems. With a little effort, and an eye on the long term, you can bring a tropical flair to your backyard by growing this delicious fruit.
Andrew Weidman lives and writes in Lebanon, Pennsylvania. He’s the vice president of the Backyard Fruit Growers (BYFG), a grassroots community of fruit enthusiasts dedicated to helping people grow healthy fruit in their own backyards. Special thanks to Lester Beachey, BYFG’s “Kiwi Uncle,” for his expertise and assistance.
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