Kiwi berries, the small, smooth-skinned relatives of the common fuzzy kiwi (Actinidia deliciosa), present a unique challenge to harvesters. These bite-sized fruits from the Actinidia arguta vine look nearly identical whether they are firm and immature or fully ripe and sweet. Determining the precise moment of harvest is important because if picked too early, they may fail to ripen properly, and if picked too late, they will soften rapidly and become difficult to handle or transport.
Seasonal Timing and Duration
Kiwi berries typically begin their harvest window in the late summer and early fall, usually spanning from late August through September, depending on the specific cultivar and the local climate conditions. Actinidia arguta varieties often ripen in early to mid-September, while some earlier types, like those from Actinidia kolomikta, may be ready in August. This timing can shift based on environmental factors, such as temperature and sun exposure throughout the growing season.
The actual period for picking the fruit is relatively short, often lasting only a few weeks once the berries begin to mature. Unlike some fruits where all berries ripen at once, kiwi berries on a single vine will mature sequentially. Growers often look for the first few berries to soften or drop as an indication that the bulk of the crop is nearing the correct stage for harvest.
Physical Indicators of Readiness
When checking for ripeness on the vine, the focus is on subtle sensory and visual changes, since the fruit remains green throughout its maturation. An immature berry appears glossy, firm, and opaque, but as it nears readiness, the skin will begin to dull slightly and become more translucent.
The most practical test for home growers is the gentle “thumb test,” which involves carefully squeezing the berry. The fruit is ready to be picked when it yields to slight pressure, indicating a small degree of softening, but is still firm enough not to split or bruise easily.
If the fruit has reached physiological maturity, it should also detach easily from the vine, sometimes with just a light tug. Commercial growers often use a refractometer to measure soluble solids content, or sugar levels, aiming for a range of 6 to 8 degrees Brix at harvest to ensure optimal post-harvest quality.
The Post-Harvest Ripening Process
Kiwi berries are classified as a climacteric fruit, meaning they continue their ripening process even after being separated from the vine. This characteristic allows them to be picked when they are still firm and sturdy, preventing damage during handling and transportation.
Once picked, the berries must be allowed to ripen at room temperature, which typically takes between three to five days. During this period, the fruit softens, and complex starches convert into sugars, concentrating the sweet flavor. This process can be accelerated by placing the berries in a paper bag with an ethylene-producing fruit, such as a banana or an apple, which releases the natural plant hormone that stimulates ripening.
For long-term storage of firm, unripe berries, refrigeration at cold temperatures (near 0°C) is effective and can maintain quality for at least six weeks. Once the berries have softened and become fully ripe, they should be moved to the refrigerator to slow down further degradation. Ripe kiwi berries stored in the coldest part of the refrigerator will typically maintain their quality for up to two weeks.