Virginia Cooperative Extension - Knowledge for the CommonWealth

New Options for Field and Greenhouse Strawberries

Commercial Horticulture Newsletter, March-April 1998

Charlie O'Dell, Extension Horticulturist

Department of Horticulture
Virginia Tech (0327)
Blacksburg, VA 24061

  • For 1998 we are excited about testing a new transplanter design for mechanically setting bare root strawberry plants through plastic mulch. Our earlier research found that late June/early July was an optimum time for transplanting bare root plants for hill system culture on plastic mulch. However, difficulty and high labor costs of hand planting bare root plants through plastic mulch do not create an attractive option of field plant stand establishment for this production system. Plan to visit our field day test of this new commercially developed transplanter here at our Kentland Research Farm on Friday afternoon, June 19 at 1 PM, near Va. Tech at Blacksburg, Virginia. As that date draws closer, call my secretary, Donna, at 540-231-5445, to confirm that date. Your input watching how this planter operates, mechanically planting bare root strawberry plants through plastic mulch, will be helpful.

  • Another plant stand establishment option, especially if a bare root transplanter for plastic mulch does not prove workable or affordable, would be to use runner tips to produce plug plants of hardy eastern varieties. This will add at least $1,000 dollars per acre higher plant costs compared to costs of easily available bare root plants of eastern varieties, but lower labor costs of mechanically transplanting plug plants would save most or all of this cost difference. Plug plants are easily and quickly planted with currently available mechanical plug planters (not water-wheel planting aids that only punch the planting holes). Mechanical plug planters are already being used by many growers in the hill system strawberry industry using plug plants as a low cost, low labor, very efficient way to establish plantings. A commercial industry would have to develop for production of large quantities of plug plants that would be needed for eastern varieties.

  • A newer technology for such a production system for producing runner tips for plug plants of both eastern and southern varieties was recently developed by Mr. and Mrs. Allen and Lynda Williford, former early growers with the Florida Strawberry Growers Association who have moved their business to Andrews, North Carolina. They pioneered the development of a greenhouse system (VerZontal tm, patent-pending) in the mid-1990's using horizontal custom-blended uv-stabilized PVC pipes with drip irrigation, so that disease-free, vigorously growing micropropagated (tissue culture-produced) mother plants are transplanted into horizontal tiers of pots filled with soilless potting medium. Runners are freely produced that hang down from the pots to be easily harvested in growth "flushes" without bending to ground level as is needed for harvesting outdoor field-grown runner tips. Imagine going into a climate-controlled greenhouse, harvesting runner tips with electric shears to fall into your container! Please note: patented varieties cannot be propagated without licensing and payment of royalty fees to the originator. Royalty fees help recover plant breeding costs allowing new varieties to continue to be developed.

    In the next few years a highly productive hill system using eastern U.S. varieties in colder areas north of the Carolinas may develop by licensed producers of patented varieties using both dormant bare root nursery plants and plug plants produced from greenhouse-grown runner tips. Even if the mechanical bare root strawberry transplanter works for field growers, the greenhouse-produced strawberry runner tip industry surely will continue to develop to fill the need for earlier season greenhouse and field plug plants of both eastern and southern varieties.

    For example, a spin-off of the Williford's work, along with research by Dr. Eric Bish at North Carolina State University, is already beginning to occur: Growers are taking a good look at producing fruit of southern and far southwestern varieties such as Sweet Charlie and Chandler in greenhouses rather than in fields in colder areas! Plug plants are set in the greenhouses in late summer to early fall in sidewall-ventilated, modestly cool night-heated greenhouses, grown cool until after Christmas, then a bit more night heat with cool, naturally longer days provides fruiting through late January, February, March, April and May when outdoor solar radiation heat finally causes the fruiting plants to return to a vegetative, runner-producing stage of growth (just when you need runner tips to produce plants for summer plug plants, providing you are licensed to propagate any patented varieties).

    Imagine having "vine ripened," locally produced fresh strawberries to sell to upscale restaurants and the general public at retail prices for months instead of weeks, with no worries about flood, frost, freezes, deer, weeds, or even having to stoop over to pick the berries! New IPM strategies using beneficial mite and insect predators will refine this technology going into the new century. Currently, few crop protectants are registered as labeled for use on greenhouse strawberries for fruit production in the United States.

  • We are wondering if we could plant the mother plants of our excellent flavored, highly disease resistant eastern U.S. varieties in the greenhouse system in late summer, grow them vegetatively through the fall, fruit them in late winter or early spring for fruit potentials, then force runner tips as needed during the summer months for production of plug plants needed for our field research in this colder area. A 100 foot long x 34 foot wide greenhouse will hold close to 8,000 fruiting, then runner producing plants, 2 rows wide per tier, 4 tiers high X 8 such double-row tiers wide. Could you get 1/2 Qt of berries per plant over the spring harvest months from select eastern varieties? Could you get nearly 1 Qt. per plant over the spring harvest season? Help, our heads are spinning! One thing is for certain: the future of hill system production of strawberries appears bright, indoors and out, thanks to the work of folks like the Willifords and the on-going research of our co-workers throughout this region.

    Trade names are used in this publication for information purposes only. Virginia Cooperative Extension, Virginia Polytechnic Institute and State University, and Virginia State University do not warrant those mentioned nor do they intend to imply discrimination against those not mentioned.



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