How to Grow Kiwi
Kiwi is a delicious as well as nutrient-dense fruit with soft hairy skin and pleasant-looking cool, greenish, sweet-n-sour flesh with black seeds neatly sitting in it. Although its name suggests that it might be native to New Zealand, it’s not.
Since it’s so tasty and cool, any gardener would dream of having their own kiwi and the good news is that this dream can come true, very easily.
What is Kiwi?
Kiwi plant that can be grown in home gardens is of two types – one that is suitable for colder regions and the other suitable for warmer, frost-free regions. Both are vines.
Kiwi (Actinidia deliciosa) which is suited to warmer regions is native to the temperate parts of southwestern China and was traditionally called the “Chinese gooseberry” in English.
Kiwi plant was exported to Europe, New Zealand, and the United States in the early 20th century, and today it’s grown in these regions in a large amount.
The other variety is known as hardy kiwi or kiwi berry or kiwwiberry (A. arguta, A. kolomikta). It is cold hardy and is native to northern China, Japan, the Korean peninsula, and Russia. Its other names are dessert kiwi, cocktail kiwi, baby kiwi, and grape kiwi.
Both the varieties are packed with vitamins A, C, and E, calcium, iron, potassium, and fiber.
Kiwi is the one that is known to most people. It’s that egg-shaped, brown-colored fuzzy fruit one can find in grocery stores.
On the other hand, the fruit of hardy kiwi is green, smooth-skinned and of a size of a grape (the reason why it’s also known as “kiwi berry”) and is not commonly found in shops.
Its flavor is sweeter than the larger kiwi. Some species of kiwi berries such as A. kolomikta, are grown mainly for their beautiful, pink-variegated leaves and fragrant flowers. Unlike kiwi, hardy kiwi doesn’t need to be peeled; it can be eaten as it is.
Besides the difference in the looks of their fruits, the plants too differ when it comes to hardiness.
As suggested by its name, the hardy kiwi thrives in colder climates (USDA Hardiness Zones 4 to 7) and can even bear subzero temperatures, whereas the kiwi grows in regions where frost is occasional (Zones 8 to 9). This being said, the flowers and fruit of both varieties are very vulnerable to spring and fall frosts.
Therefore, this plant grows best in regions that have a frost-free growing season of a minimum of 200 days.
The production of fruit may be less in the beginning, but will typically increase every year as the plant matures. Once established, it will continue producing fruit for forty years or even more.
Kiwi plant is deciduous and so, its leaves fall off in late fall. But the leaves develop again in the spring.
The grower can grow kiwi plants either for its fruits or for ornamental purposes because this vine is beautiful to look at with its large, almost heart-shaped, soft, velvety leaves, and dark green to the luscious burgundy red stem.
Male and Female Plants
If a gardener is planning to grow kiwi in their garden, especially for fruit, they should know that kiwi plants are dioecious which means that female and male flowers grow on separate plants and fruit production is possible only when both male and female plants are present.
The male plant can produce flowers, whereas the female plant can produce flowers as well as fruit.
The difference between the male and female plants becomes evident only after flowering which takes place a minimum of 3 years after planting (sometimes 5 or even more years).
Flowers of male plants have bright yellow, pollen-covered anthers at their center, whereas that of female plants have sticky stalks (stigma) at the center and white ovaries at the base.
However, a variety of hardy kiwi named “Issai” is reportedly self-fertile, if the grower has space for only one plant.
Kiwi and Kiwi Berry Varieties
‘Hayward’, ‘Common Kiwi’: This is the main female variety of the commercially grown A. deliciosa. It produces brown fruit with green flesh that is available in grocery stores and familiar to everyone. For optimal growth, it needs around a month of cool climate with temperatures ranging from 30 to 45-degree F (-1 to 7-degree C). This variety can be grown in USDA hardiness zones 7 through 9.
A. chinensis ‘Golden Kiwi’: This variety is closely related to common kiwi but produces sweeter but more delicate fruits than common kiwi. It’s also less fuzzy and more yellow. It grows best in regions that experience winter lows ranging from 10 to 30-degree F (-12 to -1 degrees C).
‘Tamori’, ‘Matua’, and ‘Chico’: Male varieties
Hardy Kiwi (Kiwiberry)
A. kolomikta ‘Red Beauty’: The fruit of this variety ripens earlier than most hardy kiwi varieties. However, this variety can be overall more temperamental. The fruit is sweet and skinny. The plants become spectacular in the fall because their foliage turns a brilliant red.
A. arguta ‘Ken’s Red’: This variety produces sweet fruits that have reddish-purple skin and dark green flesh with deep-red streaks.
A. arguta ‘Issai’: This is a self-fertile variety (i.e., it doesn’t need a male pollinator) and has small, juicy fruits. It produces white fragrant flowers in early summer.
A. arguta ‘Ananasnaya’: Also known as ‘Anna’, this variety has fruit with jade-colored skin, bright green flesh, and black seeds, and it tastes like pineapple.
A. arguta ‘Geneva’: The fruits of this variety ripen earlier than either ‘Issai’ or ‘Anna’ and the fruit is sweet and honey-flavored.
Natasha and Tatyana: Russian varieties that are said to be hardy to as low temperatures as -35-degree F.
Michigan State: This variety produces larger fruit and is hardy.
How to Grow Kiwis
Growing kiwis from seeds is fun and will definitely develop into a beautiful ornamental plant. However, the grower should remember that it may not always grow true to type which means that it may not produce edible fruits like that of the parent plant.
If one wants to grow a kiwi plant for fruits, they should buy a grafted plant from a nursery.
Kiwis typically start producing fruit 3 to 5 years after planting.
When to Plant
Kiwi plants should be planted in the spring after the threat of frost has passed.
Choosing and Preparing a Planting Site
The gardener should choose a sunny spot in their garden to let the plant grow vigorously and produce the best fruit. The spot should also be well-protected to avoid wind damage.
The spot should be on the north side of the garden in colder regions to reduce the risk of freeze-thaw damage in early spring if plants are especially susceptible.
Kiwi plants can also grow in shade; however, in shade, they won’t produce fruit. But if ornamentation is the grower’s purpose in growing this plant, the gorgeous vine serves it well with its red stems, chunky, heart-shaped leaves, and stunning, fragrant flowers.
Kiwi plants need well-drained soil as they tend to have root rot if left too wet. The soil should be slightly acidic i.e., with pH between 5.0 and 6.8.
One should amend the soil if it’s alkaline.
Temperature and Humidity
Kiwi plants prefer moderate temperature but require a period of cold (about 45-degree F) for at least a month to produce fruit. Also, the plants can tolerate hot summer temperatures up to 114-degree F, although they need extra water during the hot period.
Regarding humidity, the kiwi plant has no special demand and is just fine in the humidity levels of their respective USDA Hardiness Zones.
Kiwi vines will need tough support. They can grow 20-30 feet long and 15 feet wide. The gardener should erect a tall and strong trellis system that can support the vine and bear a weight of around 100 pounds of fruit.
Commercial growers erect 6-foot-tall wire trellises with T-bars with a gap of 15 to 20 feet between them. The vines also grow well on fences, walls, pergolas, and gazebos, if these structures are strong enough to bear the weight.
One can properly anchor a series of horizontal wires into the wall or fence every 45 cm (18 inches) which can give them the required leg-up. The wire should be thick-gauge and the grower should tighten them in place using robust vine eye screws.
While planting against a wall, the grower should make sure to plant at least a foot away from the wall’s base to prevent roots from sitting in a rain shadow.
How to Plant
As mentioned earlier, the gardener will have to plant male and female plants if they want to get a good crop. The female plants will produce fruit.
The best ratio of male to female plants is supposed to be a minimum of one male plant for every six female plants.
The gardener should keep a gap of 10 to 15 feet between every two plants to avoid tangling while still favoring pollination.
If roots are too long, the gardener will have to trim them. Then they should plant the vines just deep enough to let the roots get covered well with soil.
After planting, they should water the plants well.
Unless there are rains, the gardener should provide supplemental watering to the plants during the peak summer or other dry periods.
Kiwi plants are not at all tolerant to droughts and the gardener should make sure the soil is moist. However, these plants also don’t like wet feet therefore, the soil should be well-draining and the grower should avoid overwatering.
If any browning or drooping leaves are noticed, it means that the plant could use more water.
The gardener should not fertilize the plants during the first year. After that, they should fertilize with a well-balanced fertilizer or soybean meal in the spring.
During the first year of planting, the gardener should start training the flexible vines up support.
Kiwi plants are quite bold and brazen, and can soon become a thicket of stems and foliage if not pruned regularly. Actually, one can even train the vines into a formal espalier shape. However, pruning is a lot easier option.
The gardener should prune the lateral growth (if it’s not flowering) 2 to 3 times in the growing season. Flowers and fruits are produced on old wood.
The gardener should regularly remove water sprouts (vigorous shoots on older wood) and shoots from the trunk.
The gardener should prune female vines in the winter months, during the plant’s dormancy. Male vines should be pruned in early summer after bloom.
Hardy kiwi vines in cold areas may die back to the ground each year. In that case, the gardener should remove the dead stems and mulch with straw or leaves.
The gardener should use a three-inch layer of shredded leaves or compost to mulch kiwi plants. However, they should not pile the mulch close to the plant’s base and should keep it 3 inches away instead.
How to Propagate
Note: The gardener should note that most kiwi growers prefer buying young plants grown through propagation from nurseries rather than growing them from seeds. One of the reasons behind this is that propagated cultivars have traits that have been passed down over generations.
Moreover, most varieties of kiwi are tasty, but both male and female plants are needed for fruiting to happen.
Since one can tell the difference between the two only through their flowers and flowers are produced typically after at least three years, it’s hard to space seedlings precisely for optimal pollination and fruiting.
Growing Kiwis From Seeds
One can propagate kiwi from seeds. The process is very easy and fun. Seeds of organic fruits have supposedly higher chances to germinate and grow into hardy plants. For more exotic types of kiwis, one can order inexpensive seeds online.
There are 2 methods of propagating from seeds with some steps in common:
- Firstly, the grower should collect seeds from fully ripe, soft, organic kiwi fruits by either slicing the fruits and picking seeds with fingers or toothpicks or scooping out the pulp and separating seeds. One kiwi can contain 1000-2000 seeds.
- Now they should spread these seeds on a paper towel or tissue paper.
- They should fold this tissue paper so that all the seeds are covered.
- Now they should sprinkle some water on the paper towel to make it damp.
- After that, they should place this paper towel in a closed plastic container or Ziplock bag.
- They should place this container or bag in a warm location, but not under direct sun.
- They should keep sprinkling water on the paper towel if it dries out.
- After around 5 days, they should open the container/bag and the paper towel inside; the seeds should be sprouted.
- Now they should tear the paper towel into small pieces each having a few sprouted seeds.
- They should then place these pieces in individual small pots on a mixture of garden soil and compost, or garden soil and sand. The soil should not be hard and should not contain rocks.
- Now they should cover these pieces lightly with the planting medium so as just to cover the seeds.
- In around 15 to 20 days, tiny seedlings will grow from the sprouted seeds which they can transplant in bigger containers or in their garden.
- The grower should collect seeds in the same way as in method 1.
- They should keep containers ready with the planting medium given above.
- Now they should sow the seeds directly in the planting medium and cover them with a light layer of the planting medium.
- Now they should water the seeds to keep the medium moist.
- After around a month, they should see tiny seedlings emerging out from the potting mix which they can transplant into bigger containers or garden.
Note: Some growers recommend washing the seeds to remove the pulp from them. Although this increases the chances of sprouting a bit, it’s not absolutely necessary.
Growing Kiwis From Softwood Cuttings
Kiwis can even be propagated from softwood cuttings (cuttings taken from new growth in the summer). Here’s how:
The grower should take the cuttings in the summer months when the plant grows actively.
They should take each cutting from the current season’s growth and should have 2-3 nodes (leaves). These leaves should be fully expanded. To let the cutting perform well, they should not be taken from immature growth like the end of shoots.
The grower should then remove all the leaves except the top-most one.
Growers can use rooting hormones, e.g. those containing indole-3-butyric acid which has been found the most effective.
They should then plant the cuttings into small pots or garden beds, preferably in a glasshouse, and should keep the soil moist.
When the cuttings start developing new shoots, the grower should transfer them into 1-gallon pots containing a high-quality growing medium and should water them daily.
The potted plants should be fertilized with a slow-release fertilizer at least twice during the growing season.
Kiwi flowers are pollinated by bees and wind. The grower should grow a lot of flowering plants in their garden which will attract bees and other pollinating insects and will improve the kiwi crop.
Fruits of kiwi plants typically reach maturity in September/October which can make it face early fall frosts in some regions.
Fruits should be harvested when they become soft to touch.
Alternatively, if early fall frosts are a concern, the grower should harvest the fruits when they are still firm but have black seeds (in a sample fruit).
The grower can refrigerate these fruits for up to 6 weeks. Then they should be removed from the refrigerator and allowed to soften for a couple of days before eating.
How to Store Kiwis
The grower can store a firm kiwi in the refrigerator or a cooler for up to 6 weeks.
Firm whole hardy kiwis should be frozen on a cookie sheet and then put into plastic freezer bags.
Taking Care of Kiwi Plants
Tying Shoots to Supports
During its growth period, the kiwi plant will send out shoots. The grower should tie them to the trellis to train them to grow on the support. This will make sure the ‘trunk’ section of the plant will become strong.
Protection from Animals
Until they become fully mature, kiwi plants can be destroyed by many animals. So, the gardener should provide the necessary protection.
Cats are attracted to kiwi plant leaves just as they do towards catnip. To prevent cats from getting close to the plants, one can build a fence around the yard, put a chicken wire around each plant and spray repellents.
Deer also get attracted to the foliage of kiwi plants sometimes. One can keep deer out of their yard with either a fence around their yard or chicken wire around their plants.
Birds are not attracted by the kiwi plants' foliage, but ripe kiwi fruits can attract many bird species which love tasty and fleshy kiwi fruits. The easiest method of protection from birds is using protective nets.
Unlike several other commercially grown fruit plants, the kiwi is not attacked by insects. Hence, pesticide usage is typically not necessary.
Culling the Male Plants
Once the plants flower and the gardener comes to know which ones are the male plants and which ones are females, they can keep one male plant per 6 to 9 female plants, and remove the excess males (since only female plants produce fruits) and then space the remaining plants equally.
Pests and Diseases
Japanese beetles are beautiful to look at with their metallic green color but have a voracious appetite that makes them a great headache for fruit growers. They can be controlled by encouraging robins and other songbirds to visit the garden as the birds munch on them.
These small roundworms are often relatively harmless when in small numbers, but can weaken the plant and reduce the fruit size when are in larger numbers.
They can be best prevented by treating the soil before planting. Healthy plants can resist them better than the ones that are stressed because of drought or overwatering.
These are winged pests that are prevalent in coastal areas. They are easy to identify. Adults are oval-shaped, dark with narrow red lines on their back and young ones are red in color.
These tiny pests cannot kill the plant but can cause major leaf damage by sucking out the plant sap and thus stunting the growth. They are slender insects with fringed wings and can be controlled by blasting the affected areas with a powerful jet of water.
Spider mites can hardly be seen with the naked eye. However, they can be recognized by the fine webbing and speckled leaves they cause. They become prevalent during dry, dusty conditions. They can be quite easily controlled with neem oil or insecticidal soap spray.
Leafroller caterpillars are typically considered not a major pest for kiwi plants, but when they feed on the fruit, they become extremely damaging.
The grower should avoid chemicals as they can kill beneficial insects like parasitic wasps and tachinid flies which feed on leafrollers.
A safe, non-toxic and effective treatment is Bacillus thuringiensis (Bt). Pheromone traps are another effective way of control.
Phytophthora Root and Crown Rot
These diseases are caused by an oomycete Phytophthora spp. and cause reduced shoot growth and chlorotic leaves. Vines may suddenly collapse or decline gradually in productivity over several seasons. Red-brown discoloration of roots and root crown can be seen when the root is cut into halves.
Good water management and applying correct fungicides can control the disease. Soil should be well-drained and water should not pool after watering or rains. Growers should allow plants to dry out between waterings.
This disease is caused by a bacterium Agrobacterium tumefaciens and reduces plant vigor, causes poor growth, small leaves, and reduced yield.
Galls may be too small to be noticed.
Control of the disease depends on the prevention of injury to kiwi vines. Existing galls can be removed surgically.
This disease is caused by the bacterium Pseudomonas syringae. It makes plants wilt and causes red, rust-colored cankers on branches which may secret red-colored discharge.
The grower should prune the infected areas by cutting 1 foot below the edge of the canker. By protecting the plant from freeze injuries during winter, the grower can reduce the severity of the disease.
This disease is caused by the bacterium Pseudomonas spp. and produces brown sunken lesions on petals and causes yellow-orange discoloration of petals. It also may cause yellow spots on leaves after rains.
The grower should avoid injuries to the plant which can allow the bacteria inside. As such no chemical control is available currently for this disease.
Armillaria Root Rot
This is a fungal disease caused by Armillaria mellea and causes the vines to collapse completely. White mycelial may develop under the bark near the soil line. The disease is caused mainly when the soil is continuously damp.
Gardeners should make sure the soil is completely free of roots that are more than 1 inch in diameter. They should also make sure the kiwi vines are provided enough water but are not overwatered.
Growing one’s own kiwi fruits can be easy, fun, and extremely satisfying as the grower will be rewarded with delicious and healthy kiwi fruits.
Although they take a long time to produce fruit, once they start fruiting, they keep it for 40-50 years and don’t need a lot of maintenance. Hence growing kiwi fruit is a project that every homeowner should undertake.