Raspberries are perennials. The canes are biennial, meaning that they grow one year, produce fruit the next, then die. The plants produce new canes each year from the roots. If you care for your raspberry vines, they will produce berries for 8-12 years. You must prepare the soil with fertilizer before you plant them, however.
Determining Fertilizer Needs
Have your soil tested so you can adjust your fertilizer to fit the needs of raspberries. Your state agricultural service can ordinarily tell you how to get your soil tested. The soil for raspberries needs to have a pH of 6.5, although they can be grown with soil acidity between 5 and 6. Sandy soils, and varieties of raspberries that fruit in the fall, need extra nitrogen. Add lime to increase pH and sulfur to decrease it; changing pH can sometimes take up to a year.
Summer or Fall Before Planting
Rototill, plow or dig compost into your soil the summer or fall before you plant raspberries. This adds nutrients to the soil and will improve drainage and aeration. Put down two to three bushels of manure for each 100 square feet. If your compost contains material that has not been decomposed, add one pound of ammonium nitrate for each 100 square feet. The ammonium nitrate will help decomposition.
Just Before Planting
The Oregon State Agricultural Extension Service recommends that you till one pound of 12-12-12 fertilizer into the soil where you are going to plant raspberries. If you can't add fertilizer then, wait a month to six weeks, then apply one tablespoon of 12-12-12 for each plant. Put it just under soil in a circle about 6-8 inches around the new shoots. If you improved the soil by adding manure, use only 1/2 tablespoon.
The Maine Agriculture Extension Service recommends 25 pounds of 10-10-10 garden fertilizer for each 1,000 square feet. You can also add enough manures, rock phosphate, or compost to deliver two pounds each of nitrogen, phosphorous and potassium per 1,000 square feet.
Ohio State University horticulturists recommend that you apply one pound of 10-10-10 fertilizer for each row of raspberries 100 feet long. Do this 10 to 40 days before you plant your raspberries.
Cultivate the soil several days before you plant your raspberry plants to break up clumps and clods and to make sure the fertilizer is well incorporated into the soil.