What says summer more than a handful of tart-sweet raspberries? Raspberries are the perfect fruit for gardeners to grow because fresh raspberries are difficult to ship and very expensive when found in grocery stores. Raspberries are easy for gardeners to grow compared with other fruit, and they don't take much space.
Raspberries are a cool-climate crop; they require a chilling period each winter to set fruit. Gardeners in Zone 8 should pick varieties of raspberries developed for the South. Those gardeners in Zone 9 and below may not be able to grow raspberries. There are varieties of raspberries that are hardy as far north as Zone 3.
Raspberries come in red, purple, yellow and black. There are summer-bearing (late June, July) and ever-bearing (small crops in June and again in August-September) varieties. Fall-bearing raspberries are just ever-bearing varieties that are pruned so that they have only one heavier crop in the fall.
Summer-bearing raspberries produce the heaviest crops; you can freeze or can the excess. If you like fresh raspberries over a long season, choose a few plants each of summer-bearing and ever-bearing. Red summer bearers include Latham (Zones 4 to 7) and Boyne and Kilarney (Zones 3 to 8). Royalty is a purple summer raspberry for Zones 4 to 8. Jewel and Bristol Black are black summer raspberries for Zones 4 to 8. Polena (Zones 3 to 8) and Hertitage (Zones 4 to 8) are two red, ever-bearing raspberries. Caroline is a good red, ever-bearing raspberry for Southern areas, Zones 4 to 8. Kiwigold is a yellow ever-bearing raspberry for Zones 4 to 8.
Raspberries should be planted in the early spring. Buy certified, disease-free raspberry plants from a good nursery. Generally raspberries are sold as dormant roots, with a little stub of stem as a handle. You can store these dormant roots in a cool place (32 to 50 degrees F) for a few days until you are ready to plant them. Sometimes you will find potted raspberry plants in nurseries. Even if you love raspberries, a small family will only need from 6 to 12 plants. Raspberries spread, and a small row will soon be larger. Plant raspberries about two feet apart in rows that are about eight feet apart.
One of the best things you can do to ensure success with raspberries is to prepare your planting area in advance. Clear the area so there is no grass or weeds left in the row. To grow raspberries so that they are easy to care for, they should be attached to a trellis system of some sort. You can put sturdy posts at the end of each row and string heavy-duty wires or cables between the posts, or you can use fencing between the posts as support. Mulch between the plants and mulch the paths or plan to mow the paths often. Once weeds and grass take over a raspberry patch it is a huge undertaking to get things cleaned up again, and the plants grow better without the competition from weeds.
About two weeks after planting, or when you notice the plants are starting to grow, they should be fertilized with 12-12-12 or similar fertilizer. Use about 1/2 pound per 25 feet of row or follow label directions. Don't let fertilizer directly touch the plants, and water after fertilizing. About six weeks later repeat the fertilization. Every year after that your raspberries should be fertilized in early spring, just as growth starts, with about one pound of 12-12-12 per 25 feet of row.
Raspberry plants do need lots of water, especially in hot weather and on sandy soils. If dry conditions develop, watering your plants deeply once a week will keep them developing fruit.
Pruning and thinning correctly is the key to keeping your raspberry plants strong and productive. The roots of raspberries are perennial, but the canes, or stems, each last only two years. Each type of raspberry requires slightly different types of pruning. If you have purchased a mixture of raspberry types, it is best to keep the types together and labeled so you know how to prune.
Summer-bearing raspberries should not be pruned at all the first year. Just tie them to the supports you have put in. They won't have a crop the first year. In the second year, after they have had a crop and it has been harvested, cut off all the canes that bore fruit right to the ground. Leave all the new young canes that have developed. New canes have green stems; old ones have brown, woody-looking stems. In the third spring thin the canes you left to about six canes per foot of row. Trim the ones you leave back to chest height, about four feet, and if they had winter-kill, trim off any dead areas. Do your pruning in early spring, just before growth starts, and make your cuts just above a leaf node. Repeat every year. Black and purple raspberries may have long side branches the second and following years that should be shortened to about 10 inches.
Ever-bearing raspberries may have a small crop the first fall. Do not cut off any canes; they will fruit again early next summer on the same canes. After those canes have produced fruit, cut them out. Don't prune any canes the third year, and thereafter, until they have borne fruit again. You can thin them out in the spring if the rows are crowded and cut off winter-killed areas. After the second year you may also want to trim the canes back to about four feet high each year in the spring.
Fall-bearing raspberries are fairly simple to prune. Fall-bearing varieties are actually ever-bearers that are pruned differently. In the first year you will get a small crop in the fall. In early spring of the second year, cut all canes right to the ground. You'll get a fall crop. Repeat every year, cutting all canes off in early spring. You will have to thin plants in the rows in spring as well.
Learn how to cultivate Vaccinium ashei, the Rabbiteye Blueberry.