Master Gardener: Being successful raising blueberries
By Jerry Vitalis, Chisago County Master Gardener
Now that the plant distribution has been completed, gardeners are finishing up planting the plants they ordered. Once again blueberries are our most popular item. A side benefit to blueberries is because they come potted, they don’t need to be planted immediately. In fact, some are still getting the soil amended for planting.
Blueberries grow best in a sunny location. Plants will tolerate partial shade but as shade increases, plants produce fewer blossoms and fruit production declines. Some may remember going up north picking blueberries. There is a misconception that because they picked them in the woods, they like shade. They forget that blueberries are found in the open areas of the woods.
Blueberries grow best in an acid soil where the pH is between four and five. For three years I ordered plants and they did nothing. I contacted Rod Elmstrand, who at that time was the Chisago County Extension Educator. Rod suggested that I have the soil tested. When the report came back that my soil had a pH of 7.5, I knew why they were not doing well.
Again Rod suggested that I amend the soil with sphagnum peat moss and elemental sulfur. I dug each hole about eighteen inches deep and about two feet at a ratio of one to one, and about ¼ cup of elemental sulfur. The sulfur helps keep the pH down. I planted them about six feet apart, as the bushes will spread out.
Avoid excessive fertilizer application on new plants, as blueberries are very susceptible to injury. Some Master Gardeners add some ammonium sulfate (21-0-0) to the plants in the spring. This helps increase plant growth and increases yield.
Some think that adding a mulch of wood chips or pine needles will help keep the pH down. While they are good for keeping the weeds away and the roots cooler, it takes years to help lower the pH.
I know it’s hard to do, but you should prune off the flower buds and weak, spindly growth, leaving enough vegetative growth to support future crops. Plants should not be allowed to bear fruit the first two years after planting. This also depends on the size of the plant.