Kiwi (Actinidia spp.)

Kiwi is a vigorous, deciduous climbing vine grown for its distinctive oval fruits. The most widely cultivated species, Actinidia deliciosa, produces fruits with fuzzy brown skin and bright green flesh speckled with tiny black seeds. The flavour is refreshing and complex — often described as a combination of strawberry, melon, and citrus — making kiwi a popular addition to fruit salads, smoothies, desserts, and savoury dishes.

Varieties

The two main types grown by gardeners are:

• Common Kiwi (Actinidia deliciosa): Large-fruited with fuzzy brown skin; requires a long, warm growing season.
• Hardy Kiwi (Actinidia arguta): Smaller, grape-sized fruits with smooth, edible skin; significantly more cold-tolerant and suitable for cooler climates.
• Golden Kiwi (Actinidia chinensis): Yellow-fleshed with a sweeter flavour and smooth bronze skin.

Nutritional Value

Kiwi is exceptionally rich in Vitamin C, often providing more than the recommended daily intake in a single fruit. It also provides dietary fibre, Vitamin K, Vitamin E, potassium, and folate, and contains the enzyme actinidin, which acts as a natural meat tenderiser.

Pollination

Kiwi plants are dioecious — male and female flowers are produced on separate plants. To obtain fruit, at least one male plant must be grown alongside female plants (typically one male to every 6–8 females). Some self-fertile varieties are available and are a practical choice for smaller gardens.

How To Grow

How to Grow Kiwi

Choosing a Variety

Select a variety suited to your climate. Hardy kiwi (Actinidia arguta) tolerates colder winters and is ideal for cooler regions, while common kiwi (Actinidia deliciosa) requires a longer warm season. For small spaces, look for self-fertile cultivars that do not require a separate male plant.

Site Selection

• Sunlight: Choose a position in full sun to partial shade. At least 6–8 hours of direct sunlight per day encourages the best fruit production.
• Soil: Well-drained, fertile soil with a pH of 5.5–7.0. Kiwi will not tolerate waterlogged or compacted ground.
• Shelter: Select a sheltered spot protected from strong winds, which can damage young shoots and flowers.

Planting

• Plant in late spring after the risk of hard frost has passed, or in autumn in mild-winter areas.
• Space plants 3–4 metres apart in the row, with rows 4 metres apart.
• Dig a planting hole twice as wide and deep as the root ball. Incorporate well-rotted compost or organic matter.
• Set the plant so the root crown sits level with the soil surface. Water in thoroughly.

Support and Training

Kiwi vines are vigorous climbers and require a strong trellis, pergola, or T-bar framework capable of supporting heavy, mature growth.

• In the first year, train the main leader up the support structure, removing competing shoots.
• In subsequent years, develop a framework of lateral arms from which fruiting spurs are trained.

Watering

Kiwi requires consistent moisture throughout the growing season. Water deeply and regularly during dry spells, especially while the plant is establishing and when fruit is swelling. Apply a layer of mulch around the base to retain soil moisture and suppress weeds.

Feeding

• Apply a balanced general fertiliser in early spring as growth begins.
• Avoid excessive nitrogen, which promotes leafy growth at the expense of fruit.
• A potassium-rich feed in early summer supports flower and fruit development.

Pruning

• Winter pruning: Remove dead, weak, or overcrowded growth and cut back lateral shoots to 2–3 buds beyond the last fruit position.
• Summer pruning: Pinch back new shoots to control vigour and improve light and air circulation within the canopy.
• Male plants should be pruned after flowering to maintain their role in pollination the following year.

Harvesting

Harvesting Kiwi

When to Harvest

Kiwi fruit is typically ready for harvest in late autumn, before the first hard frosts arrive. The fruit does not soften fully on the vine — it is harvested firm and allowed to ripen off the plant.

Signs of harvest readiness:

• Fruit has reached full size for the variety.
• The skin of fuzzy kiwi (Actinidia deliciosa) has developed a uniform brown colour; hardy kiwi skin remains smooth and green but the fruit yields slightly to gentle pressure.
• A refractometer reading of 6–8 Brix (sugar content) indicates the fruit is ready.
• Seeds inside the fruit have turned black.

How to Harvest

• Use clean, sharp pruning shears or scissors to cut the fruit stalk close to the vine, leaving a short stem attached to the fruit.
• Handle fruit gently to avoid bruising — place harvested kiwis into a padded basket or crate.
• Harvest the entire crop before a hard frost, as severe freezing will damage the fruit.

Post-Harvest Ripening

Freshly harvested kiwis are typically firm and require post-harvest ripening:

• Store firm fruit in a cool, dry location to ripen slowly over several weeks.
• To accelerate ripening, place kiwis in a paper bag with an apple or banana, which release ethylene gas and hasten softening.
• The fruit is ripe when it yields slightly to thumb pressure.

Storage

• Firm, unripe kiwis can be stored in a cool location for several months, extending the season well beyond harvest.
• Ripe kiwis should be refrigerated and consumed within 2–4 weeks.
• For long-term storage, peel, slice, and freeze portions on a tray before transferring to freezer-safe containers.

Common Problems

Common Problems with Kiwi

Pests

• Aphids: Clusters of small insects on young shoots and leaf undersides can cause curling and distorted growth. Treat with insecticidal soap solution or introduce natural predators such as ladybirds.
• Spider mites: Common during hot, dry conditions. Fine webbing on foliage and yellowing of leaves are key signs. Increase humidity around the plant and treat with neem oil or a miticide if infestations are severe.
• Scale insects: Brown or grey bumps on stems that suck sap and weaken growth. Remove by hand or treat with horticultural oil.
• Leaf rollers and caterpillars: Rolled or bound leaves indicate feeding caterpillars inside. Pick off by hand or treat with an appropriate biological control.

Diseases

• Armillaria root rot (honey fungus): Affects established vines growing in soil previously hosting infected woody plants. There is no cure; remove affected plants and roots.
• Botrytis (grey mould): Fluffy grey mould appears on fruit, stems, or foliage in humid or wet conditions. Improve air circulation through pruning and avoid overhead watering.
• Phytophthora root rot: Caused by waterlogged soil. Plants show yellowing, wilting, and rapid decline. Ensure excellent drainage and avoid overwatering.
• Bacterial canker: Causes sunken, oozing lesions on stems. Prune out affected wood and disinfect tools between cuts.

Cultural Problems

• No fruit: Most commonly caused by the absence of a compatible male pollinator plant, or by insufficient bee activity during flowering. Ensure correct planting ratios of male to female plants.
• Poor fruit set: May result from late frosts damaging flowers, excessive nitrogen feeding, or insufficient sunlight.
• Frost damage: Young spring growth is vulnerable to late frosts. Protect with fleece or horticultural cloth when frost is forecast during the growing season.