Site- Air and soil drainage are prime considerations when selecting a site for planting raspberries. It is important that cold frosty air can drain downhill, away from plants. Damage by late frost to buds or blooms can cause poor crops.
Although raspberries require plenty of moisture, soil drainage is very important. The ideal soils would be sandy loams or loamy clay. Heavy clays are poorly drained. Winter injury often occurs on poorly drained sites. On the other hand sandy soils can lack moisture to produce good berries. Soils that are too heavy or too light can be improved by liberal additions of organic matter.
Raspberries should not be grown in soil that has grown strawberries, tomatoes, potatoes, eggplant or peppers in the last 3 to 4 years. All of these are susceptible to verticillium wilt, which can cause heavy loss of raspberry plants.
How to Plant- Be sure to keep plant roots moist during planting. The planting hole should be big enough that the roots will not be cramped. Do not set the plants any deeper than they grew in the nursery. Firm the soil well around roots and water. The tops of red raspberries should be cut back to 6 inches, and the old canes on purple and black raspberries should be cut very short. This is to have as little old wood carried over from the nursery as possible, as old wood is a likely source of disease.
Red raspberries should be planted 2 ½ to 3 feet apart, space black and purple varieties 3 to 4 feet apart. Distance between rows should be a minimum of 6 feet. The rows themselves should be kept narrow to improve air movement, ease of picking and enough sun light for all fruit. A support system will allow closer planting, increased fruit due to taller canes, and cleaner fruit.
Black and purple varieties are sometimes planted in hills. Plants should be 3 to 4 feet apart and each should be allowed to develop 6 or 8 canes Each plant should be supported by a stake.