Growing kiwi in Michigan may seem like an anomaly to the novice gardener, but fortunately, kiwi is not limited to just warm weather climates. If you select a kiwi species hardy enough to survive Michigan’s winters, such as Actinidia arguta (which coincidentally has a cultivator known as the “Michigan State"), you’ll be surprised to learn that they can tolerate winters down to USDA plant hardiness zone 4. Therefore, except for a small area in the northwest corner of the state (which is zone 3), most Michigan gardeners can get out their garden gloves and plant hardy kiwi plants in the spring after the last frost.
Choose a site in which to plant the kiwi. Avoid areas where standing water is common, such as near a downspout or low-lying area. Kiwis prefer sunny areas and, since they are vines, need support to grow, such as a sturdy fence or trellis. Kiwi trellises are available at many nurseries, or you can make your own to your liking, such as one made with two 6-foot posts to form a T-shaped trellis.
Prepare the planting bed, especially if the area has never been cultivated before. Turn over the top 12 inches of soil and mix in about 4 inches of compost or peat moss.
Plant the kiwis. One male for every two to eight female plants is necessary for pollination. Plant the male in the middle of the female plants. Plants should be planted between 8 and 16 feet from one another. The closer the planting, the more pruning you will have to do.
Apply about 3 inches of mulch, such as manure or straw. Do not allow the mulch to touch the bottom of the plant. Mulch will help the plant conserve water and keep the soil temperatures more consistent. It will also decompose and add valuable nutrients to the soil.
Water the kiwi plants when the kiwis start growing in the spring (usually around May in Michigan). Water when rain amounts equal less than 1 inch a week; however, during the summer, you may need to water two to three times a week to prevent the plant from drying out, which happens quicker when temperatures rise.
Train your kiwi along your support system. Loosely tie canes so they grow upward and laterally. Only allow a few canes to grow in any one direction to avoid overcrowding. The best canes are those that grow straight. Canes that bend and twist will die if they curl around another cane or around the support system.
Gently squeeze your kiwi with your thumb and finger. When more than 2 percent of the healthy looking kiwis are soft, harvest the whole crop. Store unripe kiwis in the refrigerator for slow ripening (up to eight weeks) or out at room temperature for quicker ripening. Harvest usually begins in mid-September in Michigan.
Prune annually at the end of the dormant season, which usually occurs in March or April in Michigan. Thin your canes so they are no closer than 8 to 12 inches from each other. Then, prune back all the remaining canes (which should be the healthiest and youngest canes) to about 2 feet.