|I have successfully started about 20 fuzzy kiwi plants from seed. I now need to know if they are winter hardy in the Knoxville, TN area (on the line between zone 6 and 7) so I know whether they can stay outside during the winter or not.|
|Kiwis will generally grow and produce well in USDA zones 5-9 so they should be fine in your gardening region. In order to produce fruit, you'll need one male plant for every 4 female plants. Identifying your new plants will be quite a challenge!
Hardy kiwis (Actinidia spp.) are vigorous growers--it's not unusual for kiwi vines to grow 20' to 30' long in a single season! Careful and rigorous pruning is essential to create strong and productive plants. For optimum fruit production, grow your vines on a T-shaped trellis. If you're growing them more as ornamentals you can train them to an arbor or trellis. (Remember, you'll need both male and female plants to get fruit.) Here is information on pruning for optimum fruit production; you can be a little less precise for ornamental plants.
In the first year, limit each plant to one vertical shoot, and direct that shoot to the top of its support. That shoot will become the plant's trunk. Wire or tie it loosely to the support. Allow it to grow all season and overwinter; then, once the coldest part of winter is past, prune this vine back to the top of its support.
In the second growing season, select two strong side branches near the top of the trellis and train them horizontally along the support. In the second dormant season, prune the side branches back to 1 to 2 feet long (12 to 18 buds on each). New branches will sprout from these side branches and become next year's fruiting wood.
From the third year on, prune female kiwis in the dormant season so that fruiting branches are at least 6 inches apart along the main branches. Cut out any dead or weak wood, and all tangled branches. Cut off branches that reach the ground or are so close that their fruit clusters could reach the ground.
In cooler areas, prune males back hard in summer. Prune as often as necessary thereafter to keep them tidy and to prevent them from overtaking the female vines. Restrict pruning to spring and fall in hot climates because bare branches are susceptible to sunburn. Whenever you prune, be sure to leave some of the previous year's wood so the plants flower and produce pollen.
Note that kiwis will bleed sap if pruned as growth begins in the spring, so be sure to do your dormant pruning in mid to late winter, after the coldest weather has passed but before the plant breaks dormancy.