University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article


STRAWBERRIES--HARVEST AND RENOVATION
 
Dr. Leonard Perry, Extension Professor
University of Vermont
 
If you're growing strawberries, you've probably discovered why they are the most popular small fruit for home gardeners.  If you've chosen appropriate cultivars (cultivated varieties) and a suitable site (especially well-drained soil not in a frost pocket), some proper care should enable you to get several years of harvests from your plants.
           
Let's begin with the harvest.  Make sure you pick all ripe berries, even those overripe.  Left on the plants the berries will rot and lead to disease, often gray mold or botrytis, which can reduce the vigor and life of your plantings.
           
Especially during wet periods of the growing season, watch for gray mold that looks just like its name-- a gray fuzzy growth on leaves and fruits.  There are chemicals you can use for this, but merely increasing air circulation through keeping weeds away and giving plants more spacing may be all that is needed. Much more on this disease, as well as other strawberry problems and a diagnostic tool for them, can be found online (www.gardening.cornell.edu/fruit).
           
Once you harvest berries, avoid the temptation to wash them until you're ready to store or eat.  This will reduce their usual life of 2 to 7 days.  Berries store longest between 32 and 36 degrees (F) and about 90 percent relative humidity.  The crisper drawer of a refrigerator works well. 
           
In addition to their look and taste, a beauty of strawberries is that they are easy to store.  You can dry, freeze, make fruit leathers, or make jams and preserves.  Freezing is easy if you have room, such as in a chest freezer.  You can simply put berries in a container and freeze, mix first with a bit or sugar or sweetener (sugar has some preservative properties that sweeteners don't), or cover with a sugar syrup.  Large berries are better sliced or crushed prior to freezing.  Figure about two-thirds quart of berries will give about a pint when frozen.  On the other end, when thawing, use berries before they are fully thawed unless you want a soupy mush.
           
Once you've dealt with your final harvest of June-bearers, turn your attention back to the plants.  Everbearing cultivars should last 3 years or more before you'll need to make new hills and replant.  If either types are looking weak, lack vigor, or didn't produce well, maybe it's time for a change.  Once they're removed, plant cover crops such as wheat, rye, or clover for the next 2 or 3 years.  These will help eliminate any strawberry diseases that may be present.
           
Choose a new site during summer for next spring's plantings, which allows time for soil preparation (such as adding compost) and weed removal (such as with tilling and cover crops).  Don't plant strawberries in the same space that was planted in the last 3 years with tomatoes, peppers, eggplant, potatoes, raspberries, blackberries, or of course strawberries.  These all can harbor diseases or pests that can attack strawberries.
           
If, on the other hand, your plants look fine and vigorous, plan to keep them another year.  Everbearers wont need any additional care, other than the usual watering and removal of runners.  You'll want to renovate the rows of June-bearers within a week or two after the last harvest.
           
Begin bed renovation by cutting back plants to about 2 inches above the crowns.  This can be done with hedge shears, or perhaps even a mower set high.  Just make sure the crowns aren't damaged. 
           
Hand move or sweep runners back into the rows, narrowing the rows to about 10 to 12 inches wide.  You can also do this tilling or with a hoe down the paths between rows.  Plants should be about 6 inches apart, with about 5 or 6 plants per square foot of row.  Dig and replant rooted runners to fill in bare spots.  Fertilize with 1 to 2 pounds of a complete fertilizer per 100 square feet of row, watering in well afterwards.  Keep plants well-watered, and weeded.
           
While choosing varieties resistant to the main diseases, and planting in well-drained soil, will help avoid many disease problems, watch for certain pests.  If your plants are in soil that was previously cultivated, and not sod, you may avoid grubs that feed on roots.  Weevils can lay eggs in the buds, causing them not to open and so not produce fruit.  The tarnished plant bug may appear around bloom time, feeding on flowers with the result being misshapen or no fruit.
           
Keep beds free of weeds, and fruit on straw off the ground, and you may avoid sap beetles feeding on them.  Slugs are more a problem in damp climates and seasons.  Spittlebugs are common, forming a white frothy foam around them, yet don't usually cause serious harm but rather are just unsightly.  Other less common pests include Japanese beetles, aphids, thrips, leafhoppers, leaf rollers, and grasshoppers.
           
Treat the renovated rows as you did the first year, fertilizing again in late summer or early fall to help promote good flower bud formation for next year.  As the previous year, cover plants when the ground starts to freeze with straw, evergreen boughs, or similar.  One bale of straw should cover about 100 square feet.  Make sure you don't use hay, which often contains weed seeds. The following spring, uncover when temperatures are likely to remain above 28 degrees (F) without hard frosts.  Keep a frost blanket, such as spun-bonded fabric, available in case needed.  These usually come in two or more weights, the thicker giving more frost protection.
   

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