Strawberry Yield, Harvest, and Storage

How much strawberries can yield?

Strawberries are a high-value crop with good yield potential. For farmers to maximize their yield and fruit quality (higher prices and revenue), they need to understand the factors that can influence the yield and fruit quality and take measures to manipulate them efficiently. Some key factors are the:

variety
cultivation system
plant density
availability of water (+nutrients)
environmental conditions

The environmental conditions and the water availability are considered to be the two most important factors. Climate change and water scarcity have a negative effect on plant physiology and crop production in many areas worldwide. A strawberry plant cultivated for commercial use with sufficient access to water and nutrients can produce up to 400-800 grams (or 0.9-1.8 lb) per year.

Yield per hectare/acre:

The yield per hectare depends on plant density, spacing, variety and growing methods (open field vs. high tunnel/greenhouse):

Varieties: Everbearing and day-neutral varieties usually give slightly higher yields compared to June-bearing varieties

Growing method: In an open field cultivation, with a typical planting density 50,000–70,000 plants per hectare (20,200-28,280 plants/acre) we may receive an average yield of 15–25 tons per hectare (12140-20234 lbs/acre). On the other hand, in a high tunnel or greenhouse cultivation, where higher densities are preferred (up to 100,000 plants per hectare or 40,400 plants/acre) and the conditions are more optimum (and the season is more extended), we may have higher yield potential, reaching 30–60 tons per hectare (24281-48562 lbs per acre).

When to harvest strawberries? - Strawberry harvest time

Strawberry plants can be productive for 1 to 6 years, but they can be grown as annuals, too. The fruit development period (from blossom to fruit maturation) may vary greatly, from 25 to 38 days, with an average of 30-32 days. The length of the period mainly depends on temperature, with temperatures over 16 °C (61 °F) accelerating the ripening process. As a result, depending on the region and the variety used, harvesting can last from mid-spring to early fall (April to early October for the northern hemisphere). The fruit is ripe with a proper red color and can easily be detached without being squished.

Once the berry is fully colored, the grower can pick the fruit, keeping 2.5 cm or 0.98 in stem attached to the strawberry. Keep in mind that the fruit does not ripe after harvest (non-climacteric fruits), so the fruit must be mature enough with acceptable flavor and sugar content at the moment of the harvest. The early morning hours are the best time for picking strawberry fruit when the berries are still cool. Strawberries are delicate fruit and bruise easily, so care must be taken when harvesting. The farmer can harvest by hand-picking (most common) or mechanical harvesters (mostly for the processing industry). One worker can collect, on average, 12-15 lbs (5-7 kg) of Strawberries in one hour. Strawberries harvested more firm (less ripe) are more tolerant to post-harvest handling, but that usually comes with a cost (flavor reduction). Depending on the market and consumers' preferences, the farmer needs to find the best.

Post-Harvest Handling and Storage of Strawberries

Strawberries should be washed by the consumers just before eating them because they rot quickly. To clean the dust/soil some farmers apply dry cleaning using compressed air or air blowers. If the strawberries are intended for freezing, the fruits should be thoroughly cleaned and frozen soon after harvest to protect their quality.

Depending on the end-use goal of the product as well as the target market (country), a professional farmer should be careful and aware of the following information. As a soft fruit, strawberries are very susceptible to damage that facilitates the volatile release and should be treated and stored with great caution. Immediate (pre-) cooling of the strawberries right after harvest is necessary to preserve the good quality of the product. A 0-5 °C (32-41 °F) temperature and 90-95% relative humidity are usually applied. These conditions should remain stable throughout the storage period. Controlled or modified atmosphere storage units are commonly used. Keep in mind that most post-harvest handling processes and preservation procedures like freezing, thawing, cooking, and drying may alter the quality of strawberries (Haffner, 2000). Strawberries have very short storage and shelf life. Depending on the ripening level at the harvesting moment, strawberries stored at 0 °C (32 °F) can last up to 2 weeks, while in-room temperature lasts 3-4 days.

Quality and Safety Standards for Strawberries

Most people desire glossy, aromatic, juicy, sweet, and slightly acidic berries with high sensory attributes for raw consumption. Additionally, food safety is essential both for suppliers and consumers. Pesticide residues and heavy metals (e.g., lead contamination below 0.20 mg/kg and cadmium below 0.050 mg/kg) should be absent or below the acceptable limits (check the country legislation).

Based on the taste quality (measured in Brix), the fruits (varieties) are mainly classified into 3 categories:

Acceptable to Good: 7-8 Brix (Elsanta cultivar usually produces fruits that fall into this category).
Sweet/ Good to Excellent: 8-9 Brix (strawberries of Calinda, Sonata, Sensation, Allegro cultivars)
Very sweet / Excellent: over 9 Brix (strawberries of Magnum)

Except for taste, there are 9 more quality requirements, and the "performance" of the fruits in each of them leads to their classification into 3 main categories/classes (from the worst to the best):

Class II
Class I 'good quality
'Extra' Class' superior quality

Class I is often expected by supermarkets, while in gastronomic or exclusive market segments, strawberries of the 'Extra' class are preferred.

For the processing industry, strawberries should be medium to light red with firm flesh, mild acidity, and good aroma. Soft, white-fleshed, or overly acidic strawberries are generally unsatisfactory for processing.

Packaging for Fresh and Retail Markets

Strawberries are commonly packed in 5 kg (11 lb) boxes for bulk transport, with retail buyers often preferring smaller packages of up to 500 g (1.1 lb), such as clamshells, top-seal trays, or flow packs.

By following these guidelines on yield optimization, harvesting, and post-harvest handling, strawberry growers can ensure high-quality fruit that meets market standards for freshness, flavor, and safety.

References