The harvest season may not have ended yet; it is time to plan for the new planting. This article summarizes options for planting materials and considerations for plasticulture-grown strawberries in the region.
Purchasing plug plants
Plug plants are like vegetable transplants with actively growing root systems. Plug plants are much easier to establish than bare-root plants in the plasticulture system. They are fast planting and easily survive. The drawbacks of purchasing plug plants are the high cost and a short planting window. One plug plant costs twice as much as one bare-root plant, making the plant cost for one acre of plasticulture strawberry reach $5,000 and above.
The number of branch crowns grown in the fall is essential in determining the yield of plasticulture strawberries in the following year. To achieve adequate fall growth, ideally, growers in central to northern Indiana should target to plant by the end of Aug, and growers in southern Indiana should plant before the middle Sep. Plug plants are grown from runner tips, and runner tips are harvested in summer from colder climates in commercial production. Thus, plug plants are not commercially available until about the middle of August. Supplying the large amounts of plug plants required by field strawberry growers in a short window is one of the significant challenges in using plug plants in plasticulture strawberries in our region.
Purchasing runner tips
Because of the limited supply of plug plants in a short window and the high price, some farmers choice to purchase runner tips and grow their own plugs. This extension bulletin described the method of growing plug plants from runner tips. The process takes about four weeks, and a misting system is usually needed in the first few days after planting. In addition to the required misting irrigation system, grown own plug plants require greenhouse space and labor. Another barrier is that commercial runner tips is often sold in large quantities that may exceed a single grower’s need. Growing your own plug plants from commercial runner tips may allow fruit growers a few days to a week earlier in planting. But the planting window is still narrow and limited by runner tips’ availability and arrival date.
Harvesting runner tips from the established strawberry field
Some wonder if it is okay to produce their plug plants by harvesting runner tips from established strawberry fields. Although this approach saves costs in planting materials and could have an early start, I do not recommend so, particularly if the strawberries are grown in the open field. The runners are lying on the ground and have potentially been exposed to diseases and insect pests. Furthermore, the cultivars still in the patent period can not be propagated without a license agreement with the patent holder, even for small acreage use. This extension publication provided a comprehensive list of cultivars and their patent expiration dates.
Bare-root Plants
Bare-root plants can also be used in plasticulture production. Not only is the planting cost much lower compared to purchasing plug plants, but farmers would have a longer window to plant. Bare-root plants are typically available from the beginning of the year to June. In the plasticulture system, farmers usually order the plants in June and wait for a cool period to plant. Planting bare-root on plasticulture is a tedious job and needs to be done by experienced workers. Even so, if there was not enough water or too high temperatures after planting, significant plant loss is possible. Most farmers would choose white plastic instead of black plastic when planting bare-root plants.
Crown Plugs
Crown plugs refer to plug plants grown from bare-root plants. I am not aware of commercial supplies of crown plugs, but farmers can grow their own crown plugs if space and labor are available. Dr. C.A. Weber from Cornell University described the method of growing crown plugs in this article: Cold-stored bare-root plants were placed in 50-cell deep plug trays after trimming the roots to approximately 2 inches. The cells are filled with potting mix halfway before planting and then filled with potting mix around the roots. After watering, add additional potting mix to cover any exposed roots. The trays are watered daily and fertilized weekly. It takes about six weeks to grow crown plugs in the trays. In this period, flowering trusses and runners should be removed. Crown plugs provide farmers flexibility and the potential to plant plug plants in the middle of summer. But the additional work required to grow crown plugs limits their wide use by commercial fruit growers.
Each option has its pros and cons. Choosing the one fit best in your system and the resources you have is the key to achieving success.