How to Prune Strawberries
Pruning strawberries (Fragaria x ananassa) encourages them to grow strongly and produce plenty of fruit. Strawberries are hardy in U.S. Department of Agriculture plant hardiness zones 2 through 11. June-bearing or short-day strawberries fruit in spring and early summer; ever-bearing varieties produce strawberries through the growing season; day-neutral plants usually fruit three months after planting. Before and after pruning strawberries, wipe your pruning shear blades with rubbing alcohol to help prevent the spread of pests and diseases.
Pruning flowers on strawberries in their first year increases fruit production later. June-bearing, ever-bearing and day-neutral strawberries that have their first flowers pruned also grow more vigorously than unpruned plants.
Prune all the flowering stalks on June-bearing strawberries in the first growing season. Prune the stalks at their bases where they join the rest of the plant. Prune the first flush of flowers that appear on ever-bearing strawberries after planting. If your ever-bearing plants are growing strongly, you can allow the second flush of flowers to develop into fruits. Prune flowers on day-neutral varieties for six weeks after planting.
Selective pruning of strawberry runners helps produce matted rows of plants. Runners are shoots that grow out from plants and develop roots, which grow into new plants. Matted rows of strawberries are wide rows that cover bare soil and suppress weeds.
To create matted rows of June-bearing or ever-bearing strawberries, plant new plants 12 to 18 inches apart in rows 3 to 4 feet apart. When runners appear, encourage six from each plant to form roots. Weigh them down, evenly spaced around the plants, with small stones or U-shaped pieces of wire at their nodes, which are bumps on the stems. Prune all other runners that appear at their bases where they join the rest of the plant.
Grow day-neutral strawberries 9 inches apart in rows 3 to 4 feet apart. Prune all runners on day-neutral plants in the first year, and allow them to form matted rows in the second and third year.
Ribbon rows are rows of single strawberries. Growing strawberries in ribbon rows allows air to circulate and reduces the risk of pests and diseases.
To grow June-bearing, ever-bearing and day-neutral strawberries in ribbon rows, space the plants 4 to 9 inches apart in rows 2 to 3 feet apart. Prune all the runners that appear through the life of the plants. To help prevent problems with weeds, spread a 2-inch layer of sawdust or a 4-inch layer of clean straw between the strawberry plants.
Strawberries suffer from a fungal disease called gray mold, but pruning helps reduce the disease's spread. Gray mold often affects strawberries in damp weather and in sites with poor air circulation. Blossoms and fruit slowly turn moldy, and finally a dusty, gray mold covers whole fruits.
Prune infected blossoms and fruit, and dead leaves, on June-bearing, ever-bearing and day-neutral strawberries. Pick healthy fruit at least every other day, and immediately refrigerate it. Water in the morning at the plant bases to help prevent gray mold.