by Jan Cashman
We love our home-grown raspberries. At one point, we had a 100 foot row of raspberries behind the nursery. This long row was enough for us and all our friends and neighbors. As we added greenhouses and needed more storage for trees, the patch had to be removed. For a few years, we went without, but in the fall of 2003 we planted a 15 foot row of Boyne raspberries on the north end of our vegetable garden. By last summer, we were picking them for weeks and had more berries than we could eat.
Raspberries (Rubus idaeus) are native to both Europe and North America. They have been cultivated in Europe for hundreds of years. Records show they were sold in Flushing, New York, at a nursery as early as 1737. In the first half of the 20th Century, Luther Burbank, the American potato breeder, introduced many raspberries hybrids. (Blackberries and black raspberries are not as hardy as red raspberries and will often freeze off at the ground, so I do not recommend them in our climate.)
There are two main classifications of raspberries, those that bear one crop in the summer (summer-bearing), and those that have two crops if you let them (everbearing, also called fall-bearing). If everbearing raspberries are cut to the ground in the fall or spring, they bear one heavier crop in the fall. Because an early frost can damage the fall-bearing varieties, our climate is better suited to the summer-bearing raspberries.
There are a number of high-quality varieties of summer-bearing raspberries. Latham raspberry is an old standby introduced in Minnesota in 1920. Over the years, the Boyne hybrid, introduced by Morden Research Station in Canada in 1960, has been popular here because of its vigor, productivity, and hardiness. Many of our customers have had success with the Mammoth Thornless variety. Its berries are large and ripen a few days earlier that Latham. And they have no pesky thorns! A variety recently introduced from Morden Research Station called Souris is supposed to be even better than Boyne– sweeter, more productive, and more resistant to spider mites.
Raspberries are easy to grow if you have a sunny, well-drained site. Most people plant them in the spring when bare root plants are available. Fall planting works, but, since we have to wait to dig the plants until they are dormant–well into October–fall planting gets awfully late in the season. Raspberries reproduce by suckering, so allow plenty of room. As your raspberry patch grows, it can infringe on other areas of your garden if you’re not diligent about removing the suckers. If your soil is heavy, add organic matter such as compost or well-rotted manure before planting. Plant raspberry starts 2 feet apart in rows 8 feet apart. Raised beds, in which the plants are often spaced closer, also work well for raspberries. In our climate, raspberries usually do not need staking.
Fertilize your raspberries with a well-balanced fertilizer once or twice a year-spring and fall. Weeds in your raspberry patch can be a problem, so start with a weed-free area before you plant. Mulch can help control weeds. For years, we sold a preemergent herbicide called Simazine (or Princep) to control weeds in raspberries. This restricted herbicide is hard to get these days. Casoron, another chemical, preemergent herbicide that is more readily available, will control many of the emerging weeds in your established raspberry patch. Preemergents need to be applied very early in the season, before the weeds are up.
Raspberry plants bear on second year’s growth. The old canes that bore last year’s berries can be cut off at the ground in early spring or fall. At that time you should also thin the canes to one every 6″ or so.
For many gardeners, deer and birds are serious pests to raspberries. We net our patch in the summer as the berries start to ripen so the birds don’t get them all. If you have deer in your yard, you may have to fence your patch. Spider mites, tiny insects that suck sap from the underside of the leaves, like to attack raspberries. Dormant oil spray applied to your raspberries in the spring before they leaf out will help control spider mites and other insect pests. Make sure any other insecticides you use are safe for edibles. There is a borer that attacks the canes of raspberries and makes the stems hollow and wilted. Raspberries infected with this cane borer should be dug up and destroyed.
If the raspberry fruit pulls off the plants easily, they are ripe. Wait until the fruit turns dark red for the sweetest berries-some varieties are darker red than others when ripe. Raspberries freeze well. I first put them on a cookie sheet in the freezer to hold their shape, and when they are frozen solid, transfer them to a freezer container.
But, we think raspberries are the sweetest when you eat them right off the plant. There is nothing better-plant some and enjoy!