Who doesn’t love raspberries? Not only are they delicious, these nutritional super-fruits are also chock-full of healthful antioxidants, vitamins, minerals, and fiber. But the jewel-like fruits are so perishable that it is almost impossible to get really fresh, ripe berries in the market. Fortunately, they are easy to grow in the home garden. With a little planning and some routine care, you'll be able to stroll out on summer mornings to pick handfuls to top your bowl of cereal or harvest enough to put up jars of homemade jam. How many bushes to plant? Well, you can never have too many raspberries, but you can expect about 35-40 pints of berries from 20 red raspberry plants once they are established.
Step one is choosing the varieties you want to grow. If you look in catalogs or go to a garden center, you'll see two different categories of raspberries for sale- summer-bearing and everbearing (sometimes called fall-bearing). To understand the difference, you need to understand a little berry biology.
The new shoots, or canes, that grow in the spring from the root system are called primocanes. These grow vegetatively the first year, then, in response to the shortening days and cooler temperatures of fall, develop flower buds that will bloom the following year. Next spring these canes, now called floricanes, will flower and then produce fruits. After they finish bearing, these two-year-old canes die. Everbearing (or fall fruiting) raspberries are a little different. Unlike the summer-bearing types, the first-year primocanes flower and set fruits on the top 10 to 12 buds in the fall, then set a smaller crop of berries the following summer on the floricanes, which then die. Some gardeners cut down all the primocanes on these fall-bearers after the fall crop, bypassing the second, smaller summer crop to get a bigger crop each autumn.
Prepare a bed for your raspberries that is 2 feet wide and as long as you like. Full sun and well-drained soil are musts. Test your soil and, if necessary, amend to bring the pH level to about 6.0. Work in several inches of compost and a complete organic fertilizer. It's a good idea to avoid planting raspberries in a spot where strawberries or members of the tomato family grew previously to avoid the possibility of transmitting a fungal disease called Verticillium wilt. And, if you can, try to plant at least 600 feet from any wild brambles to reduce the likelihood of disease transmission from the wild plants.
You'll space your red raspberry bushes 2 feet apart in the row (black and purple raspberries need a little more room, 30" and 40" respectively). But before you do any planting, you'll want to erect some sort of trellis to support the canes as they grow. This will help to keep the berries clean and make them easier to pick. One common design uses a five foot high, T-shaped support at each end of the row, with the crossbar the width of the row. Lengths of 12-14 gauge wire are strung from one crossbar to the other on each side of the bed.
If you are planting dormant, bareroot bushes, soak them in water for a couple of hours to rehydrate the roots before planting. Set them in the ground so that the crown is just at ground level. Now comes the hard part. Cut the tops of bareroot plants back to the ground; this will remove any diseases that may be present on the canes and helps to get the plants off to a good start. You don't need to cut back container-grown plants.
Raspberries have shallow root systems and will benefit from a mulch to keep weeds down and soil moisture consistent. Placing a soaker or drip irrigation hose under the mulch is a good way to assure your plants get the water they need.
Give your raspberry patch a light feeding with a complete organic fertilizer such as 5-10-10 each spring and a topdressing of compost each fall. As soon as they are done bearing, prune out the old floricanes. You can distinguish them from the greener, more succulent primocanes by their silvery-brown bark and lighter green leaves. If you notice suckers coming up outside of your bed, dig them out so your patch doesn't turn into a jungle. If the row has filled in and is crowded, thin out, leaving 3 to 5 of the strongest primocanes per linear foot.
Raspberries are generally pretty problem-free. But there are a couple of insects that you may need to deal with, chief among them Japanese beetles. These omnivorous pests enjoy a good raspberry leaf, so you may need to control them with handpicking or sprays of neem oil. If you notice the tips of your canes drooping over, the raspberry cane borer is probably at work. Look for rows of punctures about 6 inches from the tip of the cane. This is where the female beetle has laid her eggs. When these hatch, the developing larvae tunnel down through the shoot, causing it to wither. To control this pest, simply cut off and destroy the shoots below where the larvae are active.
If you see a whitish-gray powder on the leaves, it is probably a fungal disease called powdery mildew. This is often more of a problem in a crowded patch with poor air circulation, so be sure to thin out your primocanes each spring.