Hardy kiwis (Actinidia arguta and Actinidia kolomikta) are cold-tolerant, perennial vines that produce small, smooth-skinned fruits reminiscent of the common kiwifruit (Actinidia deliciosa). Unlike their fuzzy counterparts found in grocery stores, hardy kiwis boast a higher cold tolerance, making them suitable for cultivation in regions with colder climates. This article delves into the cultivation of hardy kiwis, with a focus on the ‘Anna’, ‘Issai’, and ‘Michigan State’ (MSU) varieties.

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**We proudly sell hardy kiwi at our plant nursery for local customers in Northern Michigan! (Pick-up only)

The Best Hardy Kiwi Varieties

‘Anna’ Kiwi: Originating from Russia, ‘Anna’ is renowned for its vigorous growth and abundant fruit production. The fruits are green with a reddish blush when exposed to sunlight and are celebrated for their sweet, aromatic flavor. As a female variety, ‘Anna’ requires a male pollinator for fruit set. Buy Anna Kiwi plants here!

‘Issai’ Kiwi: A unique self-fertile variety from Japan, ‘Issai’ is less vigorous than other hardy kiwis, making it suitable for smaller spaces. The fruits are smaller and can ripen unevenly within clusters. While ‘Issai’ doesn’t require a male pollinator, having one nearby can enhance fruit yield. Buy Issai Kiwi plants here!

‘Michigan State’ (MSU) Kiwi: Developed for its adaptability to colder climates, MSU produces elongated green fruits that are notably sweet. This female variety necessitates a male pollinator for optimal fruit production. We sell the Michigan State Kiwi variety locally at our plant nursery in Northwest Michigan. View our homepage for operating dates and hours!

Site Selection and Soil Preparation

Hardy kiwi vines thrive in locations that offer full sun to partial shade. While they can tolerate partial shade, planting them in full sun maximizes fruit production and enhances fruit sweetness. The ideal soil is well-drained, loamy, and rich in organic matter, with a pH ranging from 5.0 to 6.5. Incorporating organic materials like compost or aged manure into the soil before planting can improve fertility and structure.

Planting and Spacing

Plant hardy kiwi vines in the spring after the last danger of frost has passed. Space the plants approximately 15 to 18 feet apart to accommodate their vigorous growth. Since most hardy kiwi varieties are dioecious, meaning male and female flowers are on separate plants, it’s essential to plant at least one male for every six to eight female plants to ensure proper pollination. Position male plants upwind of female plants to facilitate pollen transfer, especially considering prevailing wind directions.

Trellising and Support for Hardy Kiwi Vines

Hardy kiwi vines (Actinidia arguta, Actinidia kolomikta) are vigorous growers, capable of producing long, sprawling shoots that can reach 20 to 30 feet in length. Without proper support, the vines can become tangled, making pruning, pollination, and fruit harvest more difficult. A sturdy trellis system is crucial for training the vines, ensuring maximum fruit production, and keeping the plants healthy and manageable.

Best Trellis Systems for Hardy Kiwi

There are several effective trellis structures to support hardy kiwi plants, each with unique benefits:

1. T-Bar Trellis (Recommended for Home Gardens)

The T-bar trellis, like this trellis kit by Mr. Garden, is one of the most effective and widely used support systems for hardy kiwis. It consists of:

• Posts: 4×4 or 6×6 wooden posts (or metal poles) set at least 3 feet deep into the ground for stability.
• Crossarms: A horizontal beam (4 to 6 feet long) attached to the top of the post.
• Wires: Two to three high-tensile wires running in opposite directions along the crossarm.

Advantages of the T-Bar Trellis:

✔ Encourages horizontal growth, increasing sunlight exposure.
✔ Improves air circulation, reducing the risk of fungal diseases.
✔ Keeps vines organized and manageable, making pruning easier.
✔ Supports heavy fruit loads without sagging.

Installation Tips:

• Set posts every 15 to 20 feet apart along the row.
• Use galvanized steel wire (12–14 gauge) for durability.
• Stretch and fasten wires tightly to prevent sagging under the weight of mature plants and fruit clusters.

2. Pergola Trellis (Ideal for Large Gardens or Decorative Uses)

A pergola trellis works well for hardy kiwi vines when used as an ornamental vine while still allowing for fruit production. We recommend getting a cedar trellis kit like this one to reduce the chance of rot. This system consists of:

• A strong, overhead wooden or metal frame with cross beams.
• Kiwi vines trained to grow over the top, forming a shaded canopy.

Advantages of a Pergola Trellis:

✔ Creates an aesthetic garden feature while producing fruiting vines.
✔ Provides shade for walkways, patios, or garden seating areas.
✔ Allows vines to spread over a large square-foot area, reducing overcrowding.

Installation Tips:

• Construct a strong framework to handle the vines’ weight.
• Train new shoots along the beams to encourage even growth.
• Prune regularly to prevent the vines from becoming too dense.

3. Single-Wire Trellis (Simple but Less Durable)

A single-wire trellis consists of one horizontal wire strung between posts. While this method is cost-effective and easy to install, it is less ideal for mature plants due to:

• Limited support for fruit-heavy vines.
• Less structural integrity compared to a T-bar system.

Best Used For:
✔ Young plants in the first year of growth before transitioning to a stronger trellis.
✔ Short-term support while training vines to a permanent structure.

Why a Strong Trellis is Essential

✔ Prevents Vine Collapse: Mature hardy kiwi cultivars produce dense foliage and large fruit clusters, which can weigh down weak trellises.
✔ Enhances Fruit Quality: Proper support allows for better air circulation and sunlight exposure, leading to larger, sweeter fruit.
✔ Reduces Disease Risks: A well-structured trellis prevents vines from sprawling on the ground, reducing susceptibility to fungal diseases.
✔ Aids in Pollination: Male and female flowers need optimal positioning for effective pollination. A well-maintained trellis ensures better access for pollinators.

Training and Pruning

Training Young Vines: In the first year, select a vigorous shoot to become the main trunk, training it vertically to the top of the trellis. Once it reaches the desired height, encourage lateral growth along the trellis wires to form the main framework.

Dormant Pruning: Conducted between late winter and early spring (December to March), dormant pruning involves removing up to 70% of the previous year’s growth. Focus on eliminating weak, tangled, or overcrowded canes, retaining healthy one-year-old canes spaced about 8 to 12 inches apart along the main leaders. These retained canes will bear the current season’s fruit.

Summer Pruning: Just before flowering in early summer, prune non-flowering shoots and trim flowering shoots back to four to six leaves beyond the last flower cluster. This practice enhances sunlight penetration and air circulation, promoting better fruit quality and reducing disease risk.

Pollination of Hardy Kiwi Vines

Pollination is a critical factor in ensuring fruit production for hardy kiwi plants. Most hardy kiwi varieties are dioecious, meaning they require separate male and female plants to produce fruit. While male plants generate pollen, they do not bear fruit. Female plants, on the other hand, will only set fruit when successfully pollinated by a male of the same species.

Even though certain varieties, such as ‘Issai’, are labeled as self-fertile, having a male pollinator nearby can increase fruit set and improve overall fruit size and quality. While ‘Issai’ can produce some fruit on its own, the yield and fruit development are often superior when a male plant is present.

Choosing the Right Male Pollinator

Hardy kiwi plants must be matched with a compatible male plant to ensure effective pollination. The male and female plants must be from the same species (Actinidia arguta, Actinidia kolomikta, or Actinidia deliciosa) for successful cross-pollination. For example:

• If growing ‘Anna’, which belongs to Actinidia arguta, a male A. arguta plant is needed.
• If growing ‘Arctic Beauty’, which belongs to Actinidia kolomikta, a male A. kolomikta plant is required.

A single male hardy kiwi can pollinate up to six to eight female plants, making it essential to plant them in the correct ratio to maximize fruit production.

Flowering and Pollination Timing

Male and female hardy kiwis must flower at the same time for successful pollination to occur. Most hardy kiwi vines bloom in early summer, producing clusters of white, fragrant flowers that attract bees and other pollinators.

To maximize pollination success:

• Plant male and female vines close to each other or in opposite directions along a trellis for better pollen transfer.
• Avoid pruning flowering shoots too aggressively, as this can reduce the number of female flowers and male pollen sources.
• If natural pollination is poor, consider hand-pollination by collecting pollen from male flowers and dusting it onto female flowers using a small brush.

How to Identify Male and Female Flowers

Since both male and female hardy kiwi vines produce small white flowers, it’s important to distinguish between them:

• Male flowers: Have prominent, pollen-covered stamens in the center but lack a pistil. They appear in clusters.
• Female flowers: Contain a central pistil, which develops into fruit once pollinated. They often appear as single blooms or small groups.

Proper identification ensures that the correct plants are used for pollination, preventing unnecessary planting of only one gender, which would result in no fruit production.

Factors That Can Reduce Pollination Success

Even with male and female vines in place, several factors can affect pollination:

• Late frost: A sudden temperature drop in early spring can damage flower buds, reducing the number of viable flowers available for pollination.
• Strong winds or heavy rain: These conditions can disrupt pollen transfer and reduce fruit set.
• Lack of pollinators: If bees and other pollinators are scarce, pollination may be incomplete. Encouraging pollinator-friendly flowers near the vineyard can improve natural pollination rates.
• Improper plant spacing: Male and female plants should be within 30 feet of each other to allow efficient pollen transfer.

Improving Pollination for Maximum Yield

To ensure good fruit set and higher-quality fruit production, follow these best practices:

• Plant a compatible male vine for every six to eight female vines.
• Choose a pollinator-friendly location with minimal exposure to extreme wind or rain during bloom time.
• Prune strategically to preserve fruiting wood while allowing light and air to reach developing flowers.
• If necessary, hand-pollinate female flowers for improved fruit set, especially in low-pollinator environments.

By maintaining a balanced ratio of male and female vines, selecting the right pollination partner, and ensuring proper flowering conditions, gardeners can maximize fruit production and enjoy an abundant harvest of sweet, grape-sized fruits each year.

Fruit Development and Harvest

Hardy kiwi plants take several years to mature before they produce fruit. Typically, you can expect fruit production to begin in the third to fifth year after planting. However, self-fertile varieties like ‘Issai’ may fruit as early as the following year.

Fruit Characteristics and Ripening

Unlike the fuzzy kiwifruit (Actinidia deliciosa) found in grocery stores, hardy kiwi fruit has a smooth skin and can be eaten whole. The fruits are about the size of a large grape and grow in clusters along the vines. Hardy kiwis ripen from late August to October, depending on the variety and climate.

To check ripeness:

• Firmness: Fully ripe fruits should be slightly soft when gently squeezed.
• Color: Most varieties change to a deeper green, reddish, or yellowish hue when ready.
• Taste: The flavor is a blend of tangy and sweet, often described as having a more intense taste than store-bought kiwis.

If an early frost threatens before all fruit is ripe, the best way to handle it is to harvest firm fruit and allow them to ripen indoors in a paper bag with apples or bananas, which release ethylene gas to speed up ripening.

Pruning for Maximum Kiwi Yield

Pruning plays a crucial role in fruit size, production, and plant health. Hardy kiwi vines are vigorous growers and require annual maintenance.

Winter Pruning (Dormant Season)

• Remove older wood that is no longer producing fruit.
• Keep the strongest new growth from the previous last year to encourage fruiting on young shoots.
• Thin out excess growth to prevent overcrowding.

Summer Pruning (During the Growing Season)

• Trim back rampant new shoots that are not producing fruit to focus energy on developing fruiting canes.
• Remove excess foliage around fruit clusters to increase sunlight penetration and improve fruit sweetness.

Cold Weather and Overwintering

Hardy kiwi plants can withstand cold temperatures, but young plants and new shoots are vulnerable to frost damage. To protect vines:

• Mulch around the base of the plant with straw or organic materials to insulate roots.
• Wrap young vines with burlap or tree guards in regions with extreme winters.
• Avoid pruning too late in the season, as it can stimulate tender new growth that may not harden before winter.

Best U.S. States for Growing Hardy Kiwis

Hardy kiwis can be successfully grown in many northern and temperate states, including:

Northeastern U.S. (Cold winters, humid summers)

• Maine
• New Hampshire
• Vermont
• Massachusetts
• Connecticut
• Rhode Island
• New York
• Pennsylvania
• New Jersey

These states provide the cold dormancy period that hardy kiwis require while also having warm enough summers for fruit ripening.

Midwestern U.S. (Cold winters, variable summers)

• Ohio
• Michigan
• Indiana
• Illinois
• Wisconsin
• Minnesota
• Iowa
• Missouri

Hardy kiwis do well in the Midwest, but they require protection from late spring frosts, especially in states like Minnesota and Wisconsin, where sudden temperature drops can damage new shoots.

Pacific Northwest (Mild winters, cool summers)

• Washington
• Oregon
• Northern California

Hardy kiwis thrive in the Pacific Northwest’s mild coastal climate, particularly in areas that avoid extreme heat. However, cooler summers in some parts may slightly delay ripening.

Mid-Atlantic & Appalachian Regions (Moderate winters, warm summers)

• Maryland
• West Virginia
• Virginia
• Kentucky
• North Carolina (mountain regions)

These states offer sufficient winter chill hours while still providing a long growing season, which benefits hardy kiwi fruit development.

Northern Plains & Rocky Mountain States (Harsh winters, dry climate)

• Montana
• North Dakota
• South Dakota
• Nebraska
• Colorado
• Idaho

Common Mistakes and How to Avoid Them

To ensure success, avoid these common pitfalls:

• Not planting a male pollinator: Unless growing a self-fertile variety, always plant a separate male near female vines.
• Insufficient support: A sturdy structure is needed to handle the vines’ weight.
• Neglecting pruning: Without regular summer pruning, vines can become unmanageable and reduce fruit production.
• Planting in poorly drained soil: Hardy kiwis thrive in well-drained soil; planting in heavy clay or compacted areas can lead to root rot.
• Ignoring frost protection: Use row covers in early spring to protect young plants from late frost.

Final Thoughts

Growing hardy kiwi cultivars like ‘Anna’ Hardy Kiwis, ‘Issai’, and ‘Michigan State’ is a good idea for gardeners in colder climates who want a unique, productive fruiting vine. By providing a strong trellis, proper pruning, well-drained soil, and male pollinators, these fruiting vines can produce sweet edible fruit for decades.