Raspberries are adaptable to a wide range of soil types. Iowa State University Extension and Outreach horticulture specialists share information about raspberry varieties, planting sites and times, as well as growing blackberries in Iowa. To have additional questions answered, contact the Hortline at 515-294-3108 or firstname.lastname@example.org.
Raspberries are adaptable to a wide range of soil types. They grow best in well-drained, fertile soils with a pH of 6.0 to 6.8. Raspberries grow poorly in heavy clay or poorly drained soils. Raspberries are more susceptible to diseases, such as Phytophthora root rot, in wet, poorly drained soils. Poor soils often can be improved by incorporating well-rotted barnyard manure or compost. Planting in raised beds also can improve drainage. When selecting a planting site, choose an area that receives full sun. The planting site should receive at least six hours of direct sun each day. Avoid shady areas near large trees and shrubs. Also, avoid areas that are heavily infested with perennial weeds. Perennial weeds, such as quackgrass, are extremely difficult to control in a raspberry planting. If possible, remove all wild brambles near the site to prevent the spread of virus diseases to the raspberry planting.
Suggested summer-bearing red raspberries for Iowa include ‘Boyne,’ ‘Latham’ and ‘Killarney.’ ‘Heritage,’ ‘Caroline’ and ‘Autumn Bliss’ are excellent fall-bearing red raspberries. The best purple raspberry varieties are ‘Brandywine’ and ‘Royalty.’ Black raspberries are not reliably cold hardy in northern Iowa. Gardeners in central and southern Iowa can choose from ‘Black Hawk,’ ‘Bristol’ and ‘Jewel.’ ‘Fall Gold’ and ‘Anne’ are excellent fall-bearing yellow raspberries.
Late March or April is the best time to plant dormant, bare-root raspberry plants in Iowa. If the planting of dormant, bare-root raspberry plants must be delayed after purchase, moisten the packing material around the roots of the raspberry plants and store them in a cool location, such as a garage or cellar.
Remove the dormant, bare-root plants from storage when ready to plant. If the roots of the raspberry plants are dry, soak them in water for several hours before planting. Set the raspberry plants slightly deeper into the soil than they were at the nursery. Plant yellow and red raspberries 2 inches deeper, while black and purple raspberries should be planted 1 inch deeper than previously grown. Dig a hole that is slightly larger than the spread of the plant’s root system. Position the plant in the center of the hole, spread out its roots, then backfill with soil. Water each plant thoroughly, then prune back the canes, leaving a maximum of 2 to 3 inches above the soil.
Purchase virus-free raspberry plants from a reliable garden center, nursery or mail-order company. Plants obtained from an old raspberry planting are often diseased. Virus-infected plants may appear healthy, but grow and yield poorly.
The growth and fruiting characteristics of blackberries are similar to raspberries. The blackberry plant’s roots and crown are perennial, while its stems or canes are biennial. Blackberry canes are strictly vegetative during the first growing season. These first year canes are referred to as primocanes. The following year, these same canes (now called floricanes) flower, produce fruit and then die.
In Iowa, the canes of most blackberry varieties suffer extensive winter injury. As a result of this damage, plants produce little or no fruit. However, there are two hardy varieties that can be successfully grown in the southern half of the state. ‘Darrow’ produces large fruit on vigorous, erect, thorny canes. ‘Illini Hardy’ bears medium-sized fruit. The fruit are produced on vigorous, erect, thorny canes. Primocane-bearing blackberry varieties are another option for home gardeners in Iowa. The canes of primocane-bearing blackberries don’t need to survive the winter as they produce fruit in late summer/early fall on the current year’s growth. Prime-Jim™ and Prime-Jan™ are erect, thorny plants. Fruit are medium-sized, conical, soft, good flavored and glossy black in color. In Iowa, gardeners should prune the canes of Prime-Jim™ and Prime-Jan™ back to ground level in late winter.