February 16, 2006 at 6:22 a.m.
In the following weeks I will attempt to write on each of the plant types we are offering to the public. I am starting with raspberries because that's what I claim to know most about. It would be best if we would plan ahead a year before planting any perennial fruit plants. Unlike me, there may be some gardeners who plan ahead, especially when planning to start a raspberry patch.
There are several things to consider when planning a raspberry patch, and soil fertility is one of them. The type of soil is extremely important in starting raspberries. About 90 percent of the root system is in the top 20 inches of soil where the roots must take up moisture and nutrients.
Raspberries are difficult to grow on heavy clay soil. Raspberry plants will not tolerate poorly drained soil. Even temporary-saturated soil conditions cane cause serious injury. This includes poor can growth, increased incidents of soil-borne diseases and plant death.
It's very important to know what was previously grown where you are planning to have your patch. Some pathogens and diseases can build up in the soil where certain crops were in the same area. Raspberries should not be grown where tomatoes, potatoes, eggplant, or strawberries have been grown during the previous four to five years. There could be infection with verticillum wilt, which is caused by a fungus.
Raspberries should not follow corn or beans where herbicides like atrazine were used for weed control. You can test by planting a few snap beans in a bucket of soil from the proposed site and a few in a bucket of soil from a site that you know was not treated with an herbicide.
Viruses can be transmitted to raspberries by aphids that are carried from wild raspberries to cultivated crops. To minimize the chance of infection they should be planted at least 600 feet from a wild patch. If possible, all wild berries should be removed.
Soil acidity is another important factor since raspberries grow best in soil with a PH between 5.5 and 6.5. They will not grow well in soils with a PH below 5.5 and iron deficiency may occur in soils with a PH above 7.0. Since you have time, a soil test will be the best guide on what the soil is like. Lime may be applied to increase soil PH and sulfur may be used to decrease PH. Be sure to have a qualified person guide your decisions. Soil test kits are available through our office.
Raspberries require full exposure to the sunlight and good air movement. They also need protection from wind and frost injury. Plants on the south-facing slope may ripen earlier than those on north-facing slopes. However, the warm temperatures in late winter and early spring can stimulate bud activity before the danger of damaging cold temperatures have passed.
One of the real advantages for having a year to get ready is weed control. The best control is to use Round-Up two to three times during the summer. Wait until the weeds are 6-8 inches high before spraying. By spraying more than once you are also controlling the late season weeds. Remember, it takes about 10 days in warm weather before Round-Up is completely effective.
Continue to work the area by removing rocks, clumps, debris, and all air pockets from the soil. Now the area should be in good condition for next year's planting. Next week I plan on writing about the best varieties of raspberries that you can choose from for a successful raspberry patch.
If you are planning to register for the 8th annual Chisago County Master Gardener Spring Gardening Bonanza, "Get the Dirt" Saturday, March 4, now is the time. Some sessions are beginning to fill up. If you did not receive a brochure in the mail, you can call or stop by the office to get one. You can also find it on our web page in the 'Hot Topics' box: http://www.extension.umn.edu/county/chisago.
The order form for bare root blueberry, strawberry, raspberry, grape and asparagus plants was mailed along with the Bonanza brochure. It is also on the web page and available from the office. We will not be doing classes at Bonanza on growing these fruit plants but classes will be offered as part of a separate weekly series this spring, which will also include some vegetable gardening topics.
The schedule for the 'Spring Gardening Series--Growing Edibles' will be available at Bonanza. The first of these classes will be on pruning apple trees Feb. 28, at 6:30 p.m., at the Senior Center in North Branch. Jim Birkholz from Pleasant Valley Orchard will be the presenter. He has taught this class for us for many years. The class is free and there will be time for questions.
The voicemail is available all year long at 651-674-4417. During office hours ask for the Master Gardener voicemail, after hours, select ext. 18.
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