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July is blueberry month in Minnesota. This fruit is native to North America and is fast becoming a favorite in our area. Although some of the hardy gardeners still love to pick blueberries in the wild, several varieties are available for northern gardens.

The blueberry is one of the most recently domesticated crops we enjoy. While our grain crops have been domesticated for thousands of years, blueberries go back only about a century. Franklin Loville, of the USDA, began collecting the best plants from the wilds in eastern United States in 1908 and began crossing them to get larger, tastier, and more productive berries. None of the domesticated blueberry varieties that we grow and eat today are more than two to four generations removed from their wild ancestors.

Blueberries are in the heath family, which include azaleas, rhododendrons and cranberries. They are tolerant of acid soil and have low fertility. In fact, when they are grown on alkaline soil they don’t mature well. They grow best in an acid soil with a pH of 4.0 to 5.0. When the soil is more acidic the iron in the soil is more easily solubilized and absorbed.

I first started growing blueberries three years ago. Since I have a pH of 7.5, I had to replace part of the soil. I dug the holes about two feet deep and about two feet in diameter for each plant. I planted my blueberry plants in rows about six feet apart. Next, I mixed the soil I had dug out with acid peat in about a 1:1 ratio. You can mix about one-half cup elemental sulfur in the peat/soil mixture before planting the bush. The purpose of the sulfur is to lower the pH of the soil to the desirable pH level. Other good forms of sulfur include iron sulfate. Do not use aluminum sulfate as high rates of this compound can be toxic to the roots. I fertilize with an acid fertilizer about every two weeks. You can use shredded wood chips or pine needles as a mulch to help retain moisture.

Some gardeners told me at the Bonanza that they work in wood chips in the soil to reduce the pH level. This only helps if your pH level is already low. I reminded them of a study on the Anoka sand plains. They worked in 10 tons of wood chips per acre in the soil. Ten years later the pH level remained almost the same.

One of the misconceptions about blueberries is that since they grow wild in the woods they will grow well in the shade. If you have ever picked them in the wild, you probably found them in open and well drained areas.

Another question asked at the Bonanza was if you need more than one variety for pollination? Two different varieties grown near each other so they can cross-pollinate does help production. Chippewa is the exception to this requirement. If brilliant red foliage is important, be sure to plant North County along with another variety such as North Blue, St. Cloud, or Polaris for cross-pollination. If you are looking for an exceptionally small shrub, then plant North Sky, as it gets to be only one foot tall. Other varieties can grow from three to four feet tall. Again, there should be another variety planted nearby for best production.

When I planted my first 13 plants two years ago I suspect they were two-year-old plants. I bought four more plants from the Master Gardeners this spring. I also made sure that I planted different varieties. Two-year-old starter plants will be mature after five to six years. My plants looked good and I even have a few berries on some of the plants. Deer, mice, rabbits and birds are enemies of blueberries. Blossom weevils, leaf miner, stem borer, as well as several fungal diseases can attack the blueberries. I have my work cut out for me if I am going to keep critters, insects and disease away from my blueberries. I also need to learn how to prune them properly.

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