The first time I tried a hardy kiwi fruit, my world turned upside down. I was browsing a booth at a Washington DC farmers market when I spotted a quart box filled with small red and green fruits. They certainly weren’t apples, and although they slightly resembled grapes, they had thicker and less shiny skin. That’s when I saw the sign proclaiming, “hardy kiwi fruits, no need to peel.”
I quickly bought a box and popped one of the kiwis into my mouth. The juicy fruit exploded with a flavor that was sweeter and more intense than the typical kiwi. Why hadn’t I seen or tried this fruit before?
Since then, I’ve learned that the fruit’s poor shelf life limits its commercial sales. However, these plants are great fruiting vines to add to your garden if you live in growing zones 3 through 8. By planting and caring for a hardy kiwi vine, you can enjoy delicious kiwi berries for years to come.
Hardy Kiwi Overview
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What is Hardy Kiwi?
You’re probably familiar with the fuzzy kiwi (Actinidia deliciosa) found in grocery stores nationwide. While the hardy kiwi (Actinidia arguta) tastes a lot like this common fruit, it is smaller in size and lacks the namesake brown, fuzzy fibers. Instead, its smooth green or red fruits are about the size of a large grape, which makes them the perfect bite-sized snack.
Due to the hardy kiwi’s short shelf life, it’s difficult to find these fruits in the United States. You may be able to snag a pint or quart of the kiwiberries at farmers’ markets, but the best way to enjoy these sweet and juicy fruits is to grow a plant at home.
The perennial plants are woody twisting vines that grow between 10-20 feet each year. The plants begin bearing fruits in their third to fifth year and can continue producing kiwis over the next 20+ years.
Characteristics
These vines produce flowers in spring. They are dioecious, requiring male and female plants for fruiting.
The hardy kiwi, otherwise known as the kiwiberry, grape berry, or arctic berry, is a long-lived perennial vine that thrives in temperate environments. Since the plants are deciduous, they lose their leaves in the fall and regrow new foliage in the spring. Most vines grow anywhere from 10-20 feet each year and thrive on arbors and types of trellises. However, they can quickly develop into unruly plants if you forgo pruning and trellising.
The plants produce flowers on new shoots in the spring. Most varieties are dioecious, which means male and female flowers occur on different plants. Only the female flowers can produce fruit, but each flower needs to be pollinated with pollen from a male flower. The clusters of kiwis ripen sometime in late summer or early fall, and a single, healthy plant can produce up to 100 pounds of fruit.
Native Area
Originating in East Asia, this perennial at least 200 frost-free days to bear fruit.
The hardy kiwi originated in East Asia, in areas including Japan, Korea, northern China, and northeast Russia. While the plants can tolerate cold temperatures, they need to grow in a location with at least 200 frost-free days to produce fruit.
Planting
Plant seedlings after the last spring frost, ensuring one male plant for every eight females.
The best way to plant hardy kiwi is to transplant small seedlings after the last spring frost. Since most varieties produce male and female flowers on separate plants, make sure to plant at least one male plant for every eight female plants. Reputable plant nurseries will label male and female plants, making it easy to purchase the plants you need.
The vines are susceptible to wind damage, so plant them in a slightly sheltered location. Make sure the location receives at least eight hours of daily light and has good drainage.
Space individual plants ten feet apart and provide them with a supporting trellis. Once the plants begin to grow, select one to two shoots to train as stems. Loosely tie these shoots to a stake to prevent them from twisting and encourage them to grow straight up.
How to Grow
As long as you stay on top of trellising and pruning, these plants are relatively easy to grow. However, they’re not a plant you can simply set and forget.
Light
Full sun exposure maximizes flower and fruit production.
The vines grow best in full sun, but they can tolerate a few hours of shade. Plants will produce more flowers and fruit if they receive more light; the more light, the better.
Soil
They thrive in well-draining, slightly acidic soil and suffer in compacted or poor-draining areas.
Hardy kiwi vines aren’t too picky about their soil as long as it’s well-draining and slightly acidic. The vines hate sitting in wet soil, so they’ll suffer if you plant them in compacted or poorly-draining soil. If your soil is compacted, loosen it with a digging fork before planting and mix in a few handfuls of compost.
This plant is tolerant of clay soil and needs some nutrients for good flowering, and resulting good yields.
Water
For optimal growth, the woody vines need moist but not wet soil.
Kiwiberry vines like their soil to remain moist but not wet. Since dry soils can lead to reduced fruit set and fruit development and wet soils can spur the development of fungal diseases, proper irrigation is key.
The ideal irrigation schedule varies depending on the temperature, humidity, and natural rainfall. A good rule of thumb is to water when the top three inches of soil are dry.
Temperature and Humidity
This perennial withstands -30°F (-34°C) during dormancy, but late frosts can harm growth and fruiting.
As its name suggests, hardy kiwi plants can tolerate extreme cold—vines can survive temperatures as low as -30°F (-34°C). They are very cold hardy when dormant. However, late freezes can harm tender new growth as well as flowers. If a frost arrives after flower production begins, the plants may not produce any fruits. You can attempt to cover the plants with row cover in late frosts, but this is a difficult process once they are mature.
While early springs and late frosts are becoming more common in much of the United States, you can still successfully grow hardy kiwi in zones 4–9. If you have a warm microclimate and an exceptionally hardy variety of arctic kiwi, you may be able to get away with growing these vines in zone 3. The key to producing a healthy crop of kiwiberries is a frost-free season of at least 200 days and no late frosts.
Hardy kiwi vines aren’t picky about humidity and can grow well in both dry and humid climates. High humidity increases the likelihood that certain fungal diseases will develop, but proper spacing and pruning can help prevent and manage these issues.
Fertilizing
Starting in their second year, the plants benefit from gradually increased fertilization and spring compost.
Since these vines produce lots of new growth and fruit each year, they require moderate fertilization to thrive. However, avoid fertilizing new plants, as this can damage tender young roots.
Starting in the second year of growth, apply slow-release balanced fertilizer in the spring. Larger plants require more fertilizer than smaller plants, so increase the amount of fertilizer as plants grow. I also like adding a few handfuls of finished compost to the plant each spring to add a boost of beneficial microbes.
Trellising
To manage their rapid growth, proper trellising using T-bar or arbor systems is essential.
Hardy kiwis are prolific growers that can quickly take over whatever is in their path. Providing the vines with a proper trellis structure is a key part of plant care.
Growers typically use one of two types of trellises to support these vigorous plants: the T-bar system or the arbor system. The T-bar system consists of T-shaped wooden posts with strands of high-tensile wire running across the tops of the posts. The kiwi vines grow up the center of the posts and then sprawl across the wires.
Pruning
Effective pruning is crucial to prevent overgrowth and structural collapse.
Proper pruning is essential to maintain a healthy and manageable hardy kiwi plant. If you just plant one of these vines and forget about them, you’ll be left with a sprawling, heavy vine that takes over your yard or collapses whatever structure it grows up.
While there are multiple ways to prune and train these vines, the single-stem method is a popular option. The first year you plant your vine, your goal is to select one stem to be the trunk. Loosely tie this stem to a stake or other support and prune off any other stems that emerge from the base of the plant. Continue to prune off lateral shoots that emerge from the selected stem until it reaches the top of your trellising structure, then prune the main stem one inch above the trellis.
In the second year of growth, select two lateral shoots to serve as cordons or lateral branches trained to grow along a wire, arbor, or whatever other trellis you select. While you can select more than two shoots to act as cordons, stopping at two keeps the plant manageable. Let the cordons grow throughout the season, then prune them back to 10-12 nodes in the winter.
Once you have the plant’s basic structure set, it’s time to focus your pruning efforts on fruit production. These vines produce fruiting shoots that emerge from the previous year’s growth, so your goal is to keep a supply of new growth and remove unnecessary old growth. A good way to do this is to prune the previous year’s new shoots back to 10-12 nodes each winter.
Propagation
The two easiest ways to propagate hardy kiwi are cuttings and seeds, but growing from seed is less common. Propagating from cuttings allows you to form mature plants more quickly.
Cuttings
For easier rooting, propagate with softwood cuttings in late spring or summer.
You can propagate hardy kiwi from both softwood and hardwood cuttings, but softwood cuttings root more easily. Start by making softwood cuttings any time in the late spring or summer. Use a sharp and sanitized pair of pruning shears to remove a cutting of this year’s growth, then cut each shoot into six-inch segments.
Dip the bottom of each shoot in rooting hormone, then place the shoots in a container filled with well-drained potting mix. Place the cuttings somewhere warm and keep the soil mix moist but not wet. The cuttings should form roots in about a month. Once they have formed roots and developed new foliage, you can plant them into individual containers.
If you propagate from cuttings, the resulting plants will be the same sex as the parent plant.
Harvesting and Storage
The plants start fruiting in 3-5 years, with yields increasing over time.
Most hardy kiwi plants begin producing fruit in three to five years. The first harvest is small, but subsequent harvests will increase in size.
Kiwiberries appear in the early summer but start to ripen sometime in the late summer or early fall. Not all fruit on a single plant ripens simultaneously, so it’s a good idea to pick the fruits more than once.
Unfortunately, the color of the fruit’s skin isn’t a reliable way to determine ripeness. Instead, you can rely on berries’ softness and taste to determine when they’re ready to harvest. Ripe kiwiberries will be soft to the touch, taste juicy and sweet, and contain black seeds. The fruits will continue to ripen off the vine, so don’t worry if you pick them when they’re a bit underripe.
Once you harvest the kiwi, store them in the refrigerator. They will last for one to three weeks, depending on their ripeness.
Common Problems
While these vines are pretty easy to grow and maintain, keeping an eye out for the following problems will help keep your plants healthy.
Aggressive Growth
Before adding a kiwiberry vine to your garden, ensure you have the time for maintenance.
As I mentioned above, hardy kiwi vines can quickly take over fences, sheds, houses, and other plants if you forgo proper pruning and trellising.
Therefore, you should make sure you have the time and interest to maintain these plants before adding them to your garden. If left unchecked, the plants can outcompete native vegetation and become invasive.
Pests
Vines resist pests but may sometimes suffer from mites, aphids, and thrips.
Fortunately, kiwiberry vines are relatively pest-free plants. However, they can face damage from some common garden pests.
Sap-sucking pests like spider mites, aphids, and thrips use their tiny mouthparts to pierce the leaves and drink the plant’s sap. While a few of these pests aren’t a problem, larger infestations can lead to discolored leaves or leaf drop. Encouraging populations of beneficial insects like ladybugs, green lacewings, and hoverflies can help keep these pests in check. You can also spray the pests with neem oil or insecticidal soap.
Japanese beetles sometimes appear during the warmer months to feed on the foliage. The best way to control these beetles is to hand-pick them off the plants and place them in a bucket of soapy water. You can also spray beneficial nematodes in the fall to kill any grubs overwintering in the soil. This will also take care of any root-knot nematodes that colonize the soil. Space your treatments apart by two weeks, and apply them in temperate seasons only.
Diseases
Phytophthora fungi cause serious diseases, leading to root and crown rot in moist soil.
Pathogens in the Phytophthora genus cause some of the most serious hardy kiwi diseases. When soil remains moist, the fungal-like pathogens can cause both root and crown rot. Signs of Phytophthora rot include small and/or yellow leaves, foliage that quickly wilts during hot weather, and dying stems. You may also notice dark bark near the soil surface—if you cut into the stem, you’ll see reddish tissue.
The best way to handle Phytophthora is prevention. Avoid planting this vine in poorly-draining and low-lying areas. If your plant develops Phytophthora, you can try to treat the fungus with fungicides. However, replanting in a well-draining location is often a better option.
Frequently Asked Questions
Want to learn more about the unique kiwiberry vine? Check out our answers to some of the most frequently asked questions.
Most types of hardy kiwi are dioecious, meaning each plant contains only male or female flowers. In order for pollination to occur, you need at least one male and one female plant. However, the ‘Issai’ hardy kiwi is self-pollinating.
While you can technically grow hardy kiwi in large pots, growing in the ground is a better option. Since the plants develop extensive root systems, they require a pot that’s at least 25 gallons.
Some popular hardy kiwi varieties include ‘Red Princess,’ ‘Anna,’ ‘Geneva,’ and ‘Issai.’ Variety type impacts plant hardiness, fruit color, and fruit taste.
Final Thoughts
The hardy kiwi covers the landscape with sprawling vines and rewards you with delicious fruits. As long as you choose a suitable trellis and properly prune the plants, you’ll be able to enjoy fresh kiwiberries in a few years.
