How to Grow Raspberries in Zone 3B

Select a summer-bearing raspberry cultivar that is very cold-hardy. Cultivars that will do well in zone 3b include Boyne, Killarney, Nova and Festival. Latham and Newburgh are also very-cold hardy raspberry plants that should do well in zone 3b.

Select a location that receives full sunlight and is protected from direct winds. Avoid any sites that are poorly draining or areas where diseased raspberry, strawberry or solanaceous plants have grown in the previous three years. If possible, plant on a north slope. This will prevent hardy plants from sustaining damage to their tissue during the winter if temperatures suddenly rise.

Prepare your soil by tilling the site the previous fall with a plow or rototiller. Then, on the earliest possible date when the temperature no longer threatens to dip below 20 degrees, incorporate 2 to 4 inches of organic compost and rye into the soil for additional nutrients and to prevent weed growth. You may want to have your soil tested by the local university extension service to make sure that it contains the proper nutrients for successful planting. If it is lacking nutrients, such as potassium and phosphorous, which are especially important to produce healthy berries, you will need to incorporate a fertilizer higher in those nutrients into the soil in the early spring when you are preparing the site.

Dig holes into the soil that are just slightly bigger than would be enough space to accommodate the plant's root system. You want the plants to be snug, but not overcrowded in the soil. Ideally, you will plant your raspberry plant at the same depth as it was living in the nursery.

Space the plants 2 to 3 feet apart if you are planting red raspberries. Space the plants 3 to 4 feet apart if you are planting purple or black raspberries.

Add a layer of mulch to the planting site. Good mulches include wood shavings, sawdust, lawn clippings and leaves, which are usually free from weed seeds.

Water your raspberry plants according to the soil needs. Loamy soils require approximately 1 to 1.5 inches of water every seven to 10 days. Sandy soils require 1/2 inch of water every three to five days. This water should come from either rain or irrigation.

Prune your plants regularly. Once you have harvested the fruit, remove the canes that bore the fruit completely. If you are growing purple or black cultivars, cut off the tips of the new canes when they grow back in the spring. For red berries, thin the canes in the spring so that only strong, healthy canes remain approximately 7 inches apart from each other and are no more than 5 feet tall.