Kiwifruit

Fuzzy greenish brown skin and refreshing green fruit are what most of us know as kiwifruit, or simply kiwi. What you probably didn’t know is that there are actually many different types of kiwifruit, and that some of them can withstand temperatures as low as -40°F!

Kiwifruit and kiwi berries (Hiperpinguino) CC BY-SA 3.0

The word kiwi can refer to the smallest cousin of emus and ostriches (Apterygidae Apteryx), the people of New Zealand, or a delicious fruit that you might want to add to your garden or foodscape. Kiwifruit are native to China. Commercial cultivation didn’t start until the early 1900’s.

Kiwifruit cultivars

Your first decision, when growing kiwifruit, is to decide which species is best suited to your microclimate and taste. Collectively, kiwifruit are the berries of approximately 60 different woody vines in the Actinidia genus. The cultivars you see most often in the grocery are the ‘Blake’, ‘Hayward’, and ‘Saanichton’ kiwifruits. Some kiwi cultivars don’t taste good at all, but you probably won’t find them for sale at your local garden center. Nearly all of the fuzzy varieties of kiwifruit (A. deliciosa) are enjoyable to eat. Other varieties can also be quite tasty:

• Chinese egg gooseberry (Actinidia coriacea)
• hearty red kiwifruit (A. purpurea)
• golden kiwifruit (A. chinensis) - green to yellow fruit; sweeter than most; short storage life
• purple kiwifruit (A. melanandra)

Kiwifruit by species (Crowhurst et al.) A = hardy kiwi, C = golden kiwifruit, D = 'A. deliciosa', E = 'A. eriantha', I = 'A. indochinensis', P = silver vine, S = 'A. setosa'. CC BY-SA 3.0

In addition to the familiar egg-shaped kiwifruit, you can also plant fast-growing kiwi berries, a smaller, smooth-skinned version with a similar flavor. Also known as baby kiwi, cocktail kiwi, grape kiwi, and dessert kiwi, three cultivars are available:

• Arctic beauty (Actinidia kolomikta)
• hardy kiwi (A. arguta) [A]
• silver vine (A. polygama)

Kiwifruit vines need a certain number of chill hours to produce fruit, depending on the variety. Be sure to calculate your local chill hours and select a cultivar that will produce fruit for you.

How kiwi grows
​
Pollination of kiwifruit is tricky. Apparently, bees are not impressed by kiwi flowers (I think they’re lovely). Commercial kiwifruit growers often have to inundate their kiwi orchards with honey bee hives, in a practice called saturation pollination, to increase the likelihood of pollination. As a home grower, you can always hand pollinate. Also, very few kiwifruit cultivars are self-pollinating. Most kiwifruit vines are either male or female (dioecious). If you want fruit from a cultivar that is not self-pollinating, you will need at least two vines, but one male plant for every 3 to 8 female plants is ideal. Even self-pollinating vines will produce more fruit if there is a male plant nearby.

Trellised kiwi in flower (A.j.morris) CC BY-SA 3.0

Like many bare root fruit trees, kiwifruit plants are generally sold as fruit producers grafted to sturdy rootstock that have been produced asexually, with cuttings. This gives you the best of both cultivars and an assurance of fruit that will be similar to the parent plant.

How to grow kiwi

Being vines, kiwifruit grow best on a sturdy trellis or pergola. This gets the vines and fruit off the ground, provides excellent sun exposure, and ensures good air circulation. Kiwifruit vines tends to be weak, so the trellising also protects the vines from breakage. Kiwifruit grows best where it is protected from heavy winds. Vines need good drainage, but the soil must be kept moist at all times. This is a good time to put that drip irrigation system to work! Kiwis should be planted 15 to 20 feet apart, with one exception: plant one male and one female in the same hole.

​Caring for kiwifruit vines
​
Kiwifruit is borne on all the canes, but production is at its peak in the first year or two. Vines should be pruned off in their third year. One way to make this job easy it to create a three-color system of ribbons or ties. Every year, simply look for a specific color and remove those vines. When you’re done pruning, use those ribbons on the current year’s growth. Kiwi vines should be fed a high-nitrogen fertilizer, once in spring and again in early summer, to give them the nutrients they need to produce all those leaves and delicious fruit. You may need to provide frost protection in winter, depending on your location and the vine cultivar.

Kiwifruit pests and diseases

Very few insects will bother your kiwifruit vines. Armored scale, boxelder bugs, and leafrollers are all you have to watch for. Nematodes in the soil may also cause problems. Kiwifruit diseases are nearly all of the fungal variety, although a devastating bacterial disease (Pseudomonas syringae actinidiae (PSA)) has appeared in New Zealand, Italy, and Chile. Armillaria root rot, bleeding canker, botrytis fruit rot, crown gall, phytophthora root and crown rot, sooty mold, and bacterial blight are the most common diseases of kiwifruit, in the US.

Kiwifruit vines take several years to produce fruit. But it’s worth the wait!