Kiwi plants are vigorous, woody vines that use other structures for vertical support. New growers often underestimate the sheer size and volume a mature kiwi vine can achieve, leading to inadequate planning. Understanding the plant’s natural growth habit is paramount because its substantial dimensions require a specialized, robust support system. The potential size of the vine dictates the necessary infrastructure and the level of maintenance required for successful fruit production.
Maximum Potential Size of Kiwi Varieties
The size a kiwi plant reaches depends on the species, but both main types grown by home gardeners are large. The standard Fuzzy Kiwi (Actinidia deliciosa) is a highly aggressive grower that can reach heights of 30 feet or more if allowed to grow unrestrained. This vine will not only climb but also spread laterally, quickly creating a dense, heavy canopy of foliage.
The Hardy Kiwi (Actinidia arguta) is sometimes mistaken for a smaller plant, but it also possesses substantial growth potential. While its vines are slightly less massive in girth than the Fuzzy Kiwi, they can still climb 25 to 30 feet in a cultivated environment. In their native habitats, these lianas have been recorded growing up to 100 feet as they ascend into the forest canopy.
The distinction between the two types is not small versus large, but rather very large versus extremely large. Both species require significant space and consistent management to prevent them from becoming an unmanageable tangle of woody growth. A vine allowed to grow without proper training will eventually form a dense, impenetrable thicket of non-fruiting wood.
Growth Rate and Necessary Support Structures
Kiwi vines are known for their high vigor, exhibiting a rapid growth rate once established. Young, healthy vines can easily put on between 6 and 12 feet of new growth within a single growing season. The most vigorous varieties of both Fuzzy and Hardy Kiwi have been observed to grow 20 feet or more in length annually.
This rapid growth necessitates investment in a specialized, exceptionally strong support structure from the beginning. A mature kiwi vine, laden with foliage and fruit, can weigh hundreds of pounds, yielding 50 to 100 pounds of fruit annually. Common structures like residential fences or standard garden trellises are often inadequate and will collapse under the weight of a mature plant.
The most suitable structures are heavy-duty systems like T-bar trellises, sturdy pergolas, or strong arbors, typically constructed from robust 4×6 inch posts. These structures are designed to support the vine’s sheer volume and hold the fruiting canes at a manageable height of around six to seven feet. This accessible height allows the gardener to perform necessary yearly maintenance and harvest the fruit easily.
Controlling Size Through Annual Pruning
Because of the kiwi vine’s highly aggressive nature, its size in a cultivated setting is determined by the gardener’s intervention, not its biological maximum. A regimen of twice-yearly pruning is required to restrict overall size and encourage the plant to produce fruit on manageable canes. This management prevents the vine from wasting energy on excessive vegetative growth and directs resources toward fruit production.
The most significant size reduction occurs during dormant pruning, performed in late winter (typically December to March). During this period, growers remove a substantial amount of old, non-productive wood, often cutting back 50 to 70 percent of the previous year’s growth. Pruning earlier in the winter is preferable because cuts made closer to spring can cause the vine to “bleed” sap excessively as it wakes up.
Throughout the summer growing season, maintenance pruning is necessary to manage density and aerial spread. This involves cutting back excessively long, non-fruiting shoots and laterals that shade the main fruiting wood. By reducing the canopy density, summer pruning ensures enough sunlight reaches the developing fruit and the new canes, which will bear fruit the following year.