Purdue News

Strawberry beds need work now to be fruitful next summer

Once the strawberry season is over, it's time to renovate strawberry plantings by removing part of the existing bed so that new runner plants have room to set and develop into productive crowns, said Bruce Bordelon, associate professor of horticulture at Purdue University.

"Renovation is important, because strawberry crowns become less productive as they age," Bordelon said. "A two- or three-year-old crown will produce fewer flower clusters and smaller fruit than a new crown. Renovation of the planting allows a high proportion of the bed to be occupied by newly established crowns from runners."

Bordelon recommended that the renovation start as soon as possible after the harvest is completed to promote early runner set. "Early-set runners have high yield potential for next year," he said.

Here's how to renovate a home strawberry planting.

• First, mow the old leaves off just above the top of the crowns. Do not mow so low as to damage the crowns.

• Next, fertilize the planting. A soil test will help determine phosphorus and potassium needs, but a good general guideline is to apply four to six pounds of 12-12-12 or similar fertilizer per 100 feet of row. Additional nitrogen should be applied at 0.5 to 0.75 pound of actual nitrogen per 100 feet of row.

• Narrow the rows. Reduce width of the existing rows to a manageable width based on your row spacing and the aisle width desired. A final row width of 12 to 18 inches is desirable at the end of the season. Rows can be narrowed to as little as six inches during renovation. Use a rototiller, cultivator or hoe to achieve the reduction. "More berries are produced at row edges than in the middle, so narrow rows are superior to wide rows," Bordelon said. "Narrow rows allow for more sunlight penetration, and they have fewer diseases and better fruit quality."

• Thin out the strawberry plants by removing plants with a hoe or by hand. If possible, remove the oldest crowns. About half the plants can be removed in a vigorous planting without jeopardizing the row.

• Work in the straw between rows by cultivation, and then pull one-half to one inch of soil over the row. "Strawberry crowns continue development at the top, and new roots are initiated above old roots on the crown, so additional soil should be added to facilitate rooting," Bordelon said. "This also helps to cover straw in the row and provide a good rooting medium for the new runner plants."

• Remove weeds within the narrowed row by hoeing, hand pulling or spot treating with a broad-spectrum herbicide such as glyphosate.

• Water the plants as needed for plant growth and establishment of new runner plants. Strawberry plants need one inch to one and a half inches of water per week from either rain or irrigation.

• Cultivate between the rows to control weeds, and sweep runners into the row until the plant stand within the row is sufficient. "The ideal density of plants in the re-established row is five to six plants per square foot," Bordelon said. "Too many runner plants will cause them to compete with each other, which will result in low yields, excess foliage, and high disease incidence." Any runner that has not set by September should be removed, Bordelon said, because it will not have time to develop fruit buds for the following year.

• During August and September, maintain adequate moisture and fertility to aid fruit bud formation and improve fruit yield for the coming year. This is done by irrigating during these months and applying an additional one-half pound of nitrogen per 100 feet of row.

• Finally, in early December, mulch the plantings with clean wheat straw to protect the crowns from winter injury.

Source: Bruce Bordelon, (765) 494-8212;
Writer: Steve Tally, (765) 494-9809; e-mail, tally@ecn.purdue.edu
Purdue News Service: (765) 494-2096; e-mail, purduenews@purdue.edu

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