How do I provide pollination for fruit trees in a high tunnel?
Because honeybees (and some other insects, including some important pests) have problems navigating in high tunnels—presumably because the plastic cover interferes with their sun-based navigation system—high tunnel growers will have to provide pollination either by hand, or, more commonly, by purchasing bumblebee colonies. This will add a little more than $100/tunnel to the expense side of your ledger, but hand pollination is simply uneconomical (Spivak, 2012). Look online to find sources of bumblebees. Be aware that bumblebee colonies will live and work for about four to five weeks, so plan delivery accordingly.
Peaches and tart cherries are self-pollinating, so you do not have to have more than one variety in a high tunnel; nevertheless, it is still advisable to provide bumblebees so that pollination is complete. Sweet cherries, plums, apricots, apples, and pears require cross-pollination, so be sure to provide a compatible pollinizer for your main variety in each tunnel.
Table grapes have a “self-contained” pollination system, so nothing needs to be done to insure pollination for grapes.
Ready to learn more? Check out ATTRA’s High Tunnel Tree Fruit and Grape Production for Eastern Growers. This publication identifies fruits that hold the most potential for profitable high tunnel culture. It also identifies several limitations and potential pitfalls growers must recognize if such a venture is to be profitable.
Spivak, Marla. 2012. Managing Pollination in High Tunnels. University of Minnesota Extension.