In the Garden
The blueberry season is upon us. Blueberries taste wonderful and are fantastic eaten raw or baked into a great number of recipes. Besides this they are so healthy and good for you, that information on their nutritional merit alone would fill a news article. Even though this is a gardening column, I need to say that one nutritious cup is only about 84 calories, and the health benefits include dietary fiber, and a host of minerals and vitamins which contribute immensely to optimum health and wellness. Blueberries have a natural pigment anti-oxidant, proanthocyanidins, which helps protect the body from cancer, aging, degenerative diseases and infections. They also help lower blood sugar levels and control blood glucose in type II diabetes.
Blueberries do not ripen uniformly, so they require many pickings. Once the fruit begins to turn blue it can increase in size by 25 percent during the ripening period. When the berries are ripe they will be very, very blue and very sweet. If they look purple or have green on them they are not ripe. When you harvest blueberries put one hand under the cluster of berries (or a small 1 cup container) and use the other hand to roll off the ripe berries. The ripe berries should just pop off the plant; you never need to pull on the berries. Once you have finished harvesting for the day, place the picked berries on a cookie sheet so they are only one layer thick for 24 to 36 hours. This will keep them from sweating and if there are some berries that are not quite ripe, these will ripen to a beautiful deep blue. After this they will keep in the refrigerator for 2 to 3 weeks. Blueberries should not be handled or picked when they are wet because it leads to a loss of surface wax increasing the chances of decay and reduces the keeping quality of the berries.
Blueberries are great to have in your garden. But if your space is limited they are an attractive shrub around your home or can be grown in a container garden. Many varieties are low shrubs and in the spring have a profusion of white blossoms followed by the growth of green berries which turn deep blue usually the end of July and first part of August. The leaves of the shrub are also attractive. They are small, thick and oval shaped. In summer they are a deep glossy green and turn to an outstanding red foliage in autumn.
A sunny location is best for growing blueberries. Plants will tolerate partial shade, but as shade increases, plants produce fewer blossoms and fruit production declines. Nor do they like to compete with other plants for water and soil nutrients. Air movement is important to prevent both the danger of spring frost injury to blossoms and disease development.
Growing blueberries presents a challenge for most gardeners because the plants need special growing conditions. Most soils in Minnesota have a pH of about 7. Our area around Wadena County has a pH of 5.5 to 6.5, so it is good for growing blueberries. Blueberries grow best in acid soils (pH 4.0 to 5.0) and soils that are well drained, loose and high in organic matter. Blueberry plants are long lived so the time and effort put into preparing the soil is a wise investment. If the pH is not within this range the growth of the plant is slowed and the foliage turns yellow. If the pH is too high for an extended period of time the plants will die.
If you are planning a row of blueberries it is best to dig a trench and mix 4 to 6 inches of peat moss into the top 6 to 8 inches of soil. Blueberries also need soil that is well aerated and has a high water-holding capacity. This can be increased by mixing in well-rotted pine sawdust, pine needles, leaf mold, or peat moss into this soil mixture. To reduce soil pH or increase the acidity of the soil, elemental sulfur, ammonium sulfate or iron sulfate should be combined into this soil mixture. The need for fertilizer will be indicated by the plant's growth and foliage color. Generally one application of the above mentioned acid-producing fertilizer should be applied each spring when the first leaf bud breaks. Late fertilizing will encourage late growth in the fall which can cause winter injury. Blueberries respond well when mulched with wood chips or pine sawdust, which helps conserve water and reduce weed competition.
The first two years remove flowers in the spring to encourage vegetative growth. Encouragement of vegetative growth is essential for healthy plants in the following years. Production of flowers and fruit deters growth when plants are too small or weak. A good-sized healthy canopy on the blueberry plant is needed to support the fruit in future years.
If you are interested in growing blueberries, the extension service has a good fact sheet called "Blueberries for Home Landscape" which you can print off by going to Google on your computer. Type in University of Minnesota Extension Service, then go to gardening, then go to fruits. The fact sheet is under blueberries.
Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.