AMES, Iowa – Fresh strawberries are easy to grow and a favorite of many across Iowa, but growers can still encounter issues caused by weather conditions or connected to a timely harvest. ISU Extension and Outreach horticulturists can help answer your questions about how to best handle strawberries from the home garden.
When should strawberries be harvested?
Harvest strawberries when the fruit are uniformly red (fully ripe). Pick the berries with the caps and stems attached to retain firmness and quality. Pinch off the stem about ¼ inch above the cap. Don’t pull off the berries.
Strawberries should be picked about every other day in warm weather, every three to four days in cool weather. The harvest period for some June-bearing cultivars may last three to four weeks. Strawberries can be stored in the refrigerator for up to five to seven days. Optimum storage conditions are a temperature of 32 degrees Fahrenheit and a relative humidity of 90 to 95 percent.
Some of my strawberries are covered with a gray, velvety growth. What is it and how can it be controlled?
The gray, velvety growth on the strawberries is probably gray mold. It is also known as Botrytis fruit rot. Gray mold is favored by poor air circulation and a high humidity in the strawberry planting. The most commonly infected berries are those touching the soil or other infected berries.
Cultural practices can reduce losses due to gray mold. Do not fertilize June-bearing strawberries in spring. The application of a nitrogen-containing fertilizer in spring promotes lush, vegetative growth. Dense foliage slows the drying of the strawberry planting, resulting in a more favorable environment for gray mold. Control weeds in the strawberry bed. Weeds reduce air circulation and slow the drying of the strawberry plants. Mulch the planting with straw to keep the berries off the ground. Berries resting on damp or wet soil are more susceptible to gray mold.
During dry weather, irrigate in the morning when using a sprinkler. Plants dry quickly when irrigated in the morning. “Clean-pick” the strawberry planting. Harvest the strawberry planting frequently. Pick berries as soon as they ripen. Handle berries carefully during harvest to avoid bruising the fruit. Immediately refrigerate the unwashed berries. Berries that exhibit symptoms of gray mold should be picked and removed from the bed. Finally, fungicides are used by commercial strawberry growers to control gray mold. However, cultural practices are the best way to control Botrytis fruit rot in home gardens.
My strawberries don’t taste as sweet as normal. Why?
The flavor of most fruits and vegetables is influenced by weather conditions. In regards to strawberries, warm sunny weather produces the most flavorful fruit. Strawberry plants produce smaller quantities of sugars when the weather is cool and cloudy. As a result, berries are not as sweet when the weather is cool and rainy in May and June.