How to Prune Strawberries

Choosing the Right Time to Prune

Preserve green, healthy leaves throughout the year. Never prune a healthy, green leaf that is still functional. These are the regions of the plant that manufacture fruit, and removing them can decrease your strawberry yields. No matter what time of year it is, pruning should be reserved specifically for brown or diseased leaves.

Prune your strawberry plants after mid- to late February. Even pruning your plants lightly before this time can significantly decrease fruit yields. The only thing you should do before this time period is remove dead leaves, and only from plants that were planted late, have grown poorly, or endured a cold winter. Never remove healthy and functional leaves, as they are responsible for food production, proper plant growth, and survival.

Mow June-bearing strawberries after the last harvest. About 1 week following the last harvest, mow the leaves of your June-bearing strawberries 1 inch (2.5 cm) above the plant crowns. After you're done mowing, do not mow again until next year—anything earlier will destroy newer growth. Use a rake to clean up debris after mowing and prevent diseases. Avoid mowing late-season strawberries that are harvested in the final week of July.

Cut June-bearing matted rows using a rototiller after harvest. If your June-bearing strawberries are lined in 2 foot (0.61 m) matted rows, use a tiller to narrow them down to strips that are approximately 8 inches (20 cm) wide immediately after harvesting their strawberries. Focus on removing older plants and saving younger ones. Space strips about 3 feet (0.91 m) apart. Late-season strawberries that are harvested in the last week of July typically don't need to be mowed.

Trimming Your Strawberry Plants

Remove foliage from crops that bear fruit in the summer. Also known as summer bearers, these crops typically flower during the late spring and bear their strawberries in the summer. Snip foliage around 4 inches (10 cm) above their crowns—the aboveground parts that begin at soil level. Getting rid of foliage provides room for more newer leaves to kick-start new growth.

Cut old leaves from your plants to get rid of dead weight. Old leaves stop contributing to carbohydrate production, but still absorb water and nutrients. Remove these leaves to help your strawberry plants thrive without putting energy into leaves that aren't giving anything of value back. Old leaves can be distinguished by their yellow color, and lose their glossy aesthetic as they age. Dead leaves prevent air circulation in the canopy, and also leave your plants more susceptible to disease. Long stems are old plants that can be cut at the base with garden shears.

Remove runners to prevent resources from going to clone plants. Most strawberry varieties create runners (also referred to as stolons), which are horizontal connections between the primary strawberry plants that extend over the soil. Trim these connections back to their mother plant. If you don't, they will eventually create their own root system that will ultimately lead to the production of a clone plant. Removing runners prevents your plants from wasting the saccharides they generate from photosynthesis—referred to as photoassimilates—on clone plants. If growing conditions are optimal (ample sunlight and water access), runners can remain without too much of an impact on your strawberry growth. Daughter plants created by runners can be detached from the mother to start new plants after they have rooted. However, this should be done sparingly.

Remove flower stalks from summer-bearing plants. Use your thumb and forefinger to carefully remove flower stalks from plants that bear their strawberries in June. Keep an eye out for them every day, and remove them throughout the first growing season as they appear. Take a look at strawberry varieties here: https://extension.umaine.edu/publications/2184e/. Be careful not to damage the stalks of your strawberry plants as you remove their flower stalks. Only remove the flowers from everbearing plants (which produce fruit all throughout the growing season) and day-neutral plants (which produce flowers regardless of sunlight exposure). In addition, you should only remove flowers up to the middle of June.

Cut flowers when clusters are small or if you need vegetative growth. Flower clusters need to develop a crown at least 0.39 inches (9.9 mm) in diameter with at least 5 or more leaves for successful fruit production. Locate any smaller ones and remove them. Remember: the size of your flowers is correlated with the size of your strawberries. You don't want your plants to waste photoassimilates on small flowers, which is why flower removal is necessary.

Remove strawberries to prevent competition between plants. Some people suggest that you keep the number of strawberry fruits low. This is believed to reduce competition between plants and foster larger fruit sizes. But this technique is disputed, and some greenhouses skip it altogether. Keep an eye on fruit numbers and average sizes to determine if this technique works for your crop.

Slice off crowns to keep a steady density in highly vegetative plants. Since strawberry plants can create crowns—or extended shoots—from 1 or more auxiliary buds, removing them can effectively promote the development of flower buds. Avoid pruning the younger crowns—this can hinder the growth of your plants.