As we plow into the new year, gardeners with home orchards e-mail or call in asking questions about what type of fertilizer to use, when to fertilize and how much to apply for a successful crop of apples, pears, grapes and blueberries. Choosing the right food, such as a granular 10-10-10, cow manure, lime or sulfur will aid in good fruit production throughout the season.
However, the first step is to soil sample. Lab findings will convey precise results and offer suggestions for tweaking soil pH levels along with any other nutrients that may be lacking. Soil test boxes and forms can be picked up at the Extension Center.
The following are fertility tips for some of the more common fruits and berries.
Grapes: For first year plants, apply one-quarter pound of 10-10-10 in an 18-inch circle around each vine in late February to early April. Repeat every six weeks until early July. In the second year, apply one-half pound of 10-10-10 three times during the year – early March, May and June. Apply the fertilizer in a larger circle around the vine by going 21 inches or more away from the trunk. For mature vines, uniformly scatter 1 to 2 pounds of 10-10-10 under the vine in early to mid-March. In mid-June apply another 1 pound. If the average length of new growth exceeds 3 to 4 feet per season, you can reduce the amount of fertilizer applied during the growing season.
Blueberries: For first year plants, apply 1 tablespoon of 10-10-10 in a circle 1 foot away from plant after the first leaves reach full size. Repeat the application at six-week intervals until early July. In the second year, double the rate to 2 tablespoons per plant and apply when new growth begins in the spring. For mature plants, apply 1 cup of 10-10-10 in a circle 3 feet away from plant. Apply once new growth begins in the spring. Blueberries should have around 6 to 12 inches of new growth per growing season.
Fruit trees: Apple, pear and peach trees are fertilized in late winter by broadcasting under and beyond the drip line. On young trees, keep the fertilizer at least 6 inches away from the trunk. A good rule of thumb for applying fertilizer is to apply three-quarter to 1 pound of 10-10-10 per each year of the tree’s age. Observing the new growth of fruit trees each growing season will help you determine if you are applying enough or too much fertilizer. Increase rates if tree branches are less than 10 inches; decrease the amount of fertilizer if trees exhibit more than 18 inches of growth.
Strawberries: For first year plants, apply about 4 pounds 10-10-10 per 100 feet of row two to three weeks before planting. A top dressing of ammonium nitrate at 1.5 pounds per 100 feet of row should be made again in late August. When top-dressing strawberry plants, apply the fertilizer evenly and be sure to brush all fertilizer off the leaves to protect from fertilizer burn. In the second season, broadcast a fall application of a complete fertilizer e.g., 10-10-10 (3-4 lbs.) per 100 feet of row prior to mowing the strawberry foliage at renovation.
Blackberries and raspberries: These grow best on deep, well-drained soils with a pH of 5.8 to 6.5. Before planting, mix about 3 pounds of 10-10-10 per 100 square feet of soil and another 5 pounds per 100 linear feet after the start of new growth. In established plantings, apply in March well before the plant starts to produce flowers and fruit.
Christine Bredenkamp is NCSU horticulture extension agent for Jackson and Swain counties.