Environmental, Soil Requirements and Planting of Kiwi Plants

Kiwifruits are climbing plants that thrive in temperate climates and sub-tropical and Mediterranean areas (New Zealand, Italy, Chile, Greece, and California). All these regions have some common characteristics favorable for kiwi growth and production: mild winters, warm summers, and adequate rainfall.

The ideal temperature range for kiwifruit growth is between 14°C to 24°C (57°F to 75°F). The plants can tolerate temperatures up to 40°C (104°F), but prolonged exposure to such high temperatures can cause heat stress and damage the fruit (sunburn, decreased quality, and post-harvest life). On the other hand, the kiwi plants can withstand temperatures as low as -10°C (14°F). However, even a temperature of -1 °C (30.2 °F) can damage the fruits. Extreme cold can damage the vines, particularly if no snow cover insulates the roots (frost damage).

Choosing a Planting Site for Kiwis

When selecting a planting site, farmers should consider several factors to ensure optimal growth and yield and decrease as much as possible the problems and challenges they will have to deal with in the next 30-40 years.

Areas with frequent frost or extreme temperature fluctuations should be avoided.
Slightly sloped sites benefit natural drainage and are optimum for establishing your kiwi crop. Make sure the field has good drainage and does not get waterlogged. Compacted soils should also be avoided.
Kiwifruit plants need full sun for at least 6-8 hours daily to maximize photosynthesis and fruit production.
Kiwifruit prefers well-drained, fertile soils with a pH range of 5.5 to 7.0. Loamy soils are ideal, providing good aeration and drainage while retaining enough moisture. On the contrary, heavy clay soils should be avoided. The calcium carbonate (CaCO₃) should be lower than 10%; otherwise, the plants will have significant problems (mainly with nutrient uptake—iron deficiencies).
Farmers are advised to use windbreaks or plant in naturally sheltered locations (where strong winds are a common problem) to avoid putting too much stress on their plants and trellis systems due to strong winds.
Finally, kiwi plants are water-demanding, and ample water is needed throughout the growing season to produce high yields and high-quality fruits. For this reason, it is absolutely necessary to choose a field with a consistent and adequate water supply (water of good quality—read more in the article devoted to kiwi irrigation).

Soil preparation and Kiwi Planting

To establish a successful kiwi crop, proper soil preparation is essential. After selecting the planting site/field, the first step is to perform a detailed soil analysis to determine nutrient levels and pH. If the soil pH is too low, you can incorporate lime to raise it. If it is too high, sulfur can be added to lower the pH. Compost or well-rotted manure can be incorporated in soil of lower fertility and poor structure before planting the crop. Kiwi growers perform deep tillage (at least 50 cm or 1,6 ft. deep) to break up compacted soil layers. This promotes better root penetration and water drainage. In soils with erosion problems, this should be limited. Before planting the young kiwi plants, clearing the field of weeds is important to give the crop a clean start. Farmers are advised to irrigate before planting if the soil is too dry.

The best time to plant kiwi vines (usually) is in the spring after the last frost. This allows the plants to establish roots before the onset of summer heat. Usually, hardwood cuttings (15-20 cm or 6-7.9 inches long) are used as a planting material (read about that and other options in the article devoted to kiwi plant propagation). The planting material could cost around 3-8 euros a piece, depending on the country and type of propagation material used.

Planting Process and Kiwi Spacing - Planting Distances of Kiwis:

Hardwood cuttings should be planted deep enough to cover the bottom half to two-thirds of the cutting. Typically, the planting hole should be 20.3-25.4 cm (8-10 inches) deep and usually about 10-15.2 cm (4-6 inches) wide. Ensure that at least two nodes (leaf buds) are buried below the soil surface, as these will develop roots. Softwood cuttings, which are more tender and have less developed woody tissue, should be planted shallower than hardwood cuttings. You can place them in a hole 15.2-20.3 cm (6-8 inches) deep (the bottom third of the cutting should be below the soil surface) and 7.7-10 cm (3-4 inches) wide.
Proper spacing is crucial for kiwifruit plants. Typically, planting distances (for pergola and T-bar trellis) are 3-4.5 m (9.8-14.8 ft) between the plants of a row and 5-6 m (16.4-20 ft) between rows. In some cases, the row distances might be shorter or larger. However, when shorter than 4 m (13 ft), problems may arise when passing through the field with the tractor (broken vines). At the same time, dense fields have poor aeration, leading to an increased risk for fungal canopy infections (e.g., Alternaria and Stemphilium (leaf-blight)). By carefully selecting the species and following optimal planting and spacing guidelines, farmers can achieve robust growth and high yields in their kiwifruit orchards.
Farmers are advised to water the plants thoroughly after planting to settle the soil and improve good root-soil contact.
Since kiwi vines are climbing plants, providing some support, such as a small stake, is beneficial even at the cutting stage. This helps guide the initial growth and ensures the cuttings remain upright. If needed, protect the cuttings from extreme weather conditions, particularly strong winds and direct, harsh sunlight. Partial shading can be beneficial during the hottest part of the day. No pruning should be applied in the first year.

Kiwi Trellis Systems: Establishing and Supporting Your Kiwi Plants

Kiwifruit vines can grow aggressively, reaching over 6 m (20 feet). These vines can become tangled and unmanageable without proper support, leading to reduced fruit quality and increased disease susceptibility. A well-designed trellis system provides the necessary support, improves air circulation, and facilitates easier pruning and harvesting. Experienced farmers advise their colleagues to establish the trellis system before planting the crop. Different trellis systems are available.

Types of Trellis Systems for Kiwifruit

The three most commonly used systems are:

T-Bar Trellis

The T-bar trellis is one of the most popular and effective systems for supporting kiwifruit vines. Its wide use is because it provides excellent support for heavy fruit loads and facilitates good air circulation and sunlight penetration within the plant canopy.

The system consists of vertical posts with horizontal crossbars (forming a T-shape) that support multiple wires. The posts should be sturdy (wood or metal), at least 2.4 m or 8 feet tall, and placed 4.6-6 m (15-20 feet) in the plant row. The plant and the trellis system receive a lot of pressure in areas with strong winds. So, it is essential to ensure the posts have been placed deep enough (about 0.6-0.9 m or 2-3 feet) and secured. The horizontal crossbars (1.2-1.8m or 4-6 feet wide) are attached at each post's top. Typically, two to four wires (galvanized) are used horizontally between the crossbars spaced about 45.8-61 cm or 18-24 inches apart vertically.

Pergola Trellis

The pergola trellis, also known as the overhead trellis, is the second most popular system used in the kiwi field. It allows the maximization of sunlight exposure and optimum air circulation while making maintenance and harvesting easy.

It creates a canopy-like structure that allows the vines to spread horizontally above the head height. The principles of establishment are similar to those of the system mentioned above. However, the posts are a bit taller (at least 2.7-3 m or 9-10 feet) and placed in a grid pattern about 4.6-6 m or 15-20 feet apart. Crossbeams are placed between the posts to create a framework. String wires are placed across the top of the framework, spaced about 0.6 m or 2 feet apart, to support the vine growth.

Environmental, Soil Requirements and Planting of Kiwi Plants

The Single-Wire Trellis and the Vertical Shoot Positioning (VSP) Trellis are other systems used for kiwi plants. Depending on the country and the materials used, the trellis cost might be around 15,000-18,000 euros for 1 hectare.

Best Practices for Establishing Trellis Systems

When setting up a trellis system for kiwifruit, consider the following best practices:

Material Selection:

To ensure longevity, use durable materials such as treated wood, galvanized steel, or concrete for posts. You need to choose high-tensile wires to support the weight of the vines and fruit. Anchors or guy wires are used to withstand the tension from the horizontal wires and the weight of the vines.

The Importance of Proper Spacing:

You can space posts and wires appropriately to accommodate the vigorous growth of kiwifruit vines. You can ensure adequate row spacing (3.7-4.6 m or 12-15 feet) to allow machinery access/passing and crop maintenance.

Maintenance of the Trellis System Regularly:

It is very important to inspect and tighten the wires regularly to maintain good tension. If needed, you can replace any damaged or weakened posts and wires promptly and take extra measures to support the construction when strong winds are expected (especially at the end of summer and the start of autumn when the fruit is loaded).