Raspberries belong to a large group of fruits known as brambles, all in the plant genus Rubus. Three main types which can be grown in the home garden are red, black, and purple. (Yellow raspberries are albino red raspberries.) Raspberries can be grown successfully in most areas of Minnesota.
Raspberries have perennial roots and crowns, but their canes live for only two summers. Most raspberries are summer-bearing varieties. During the first year, the new green cane (primocane) grows vegetatively. The cane develops a brown bark, is dormant in winter, and during the second growing season is called a floricane. The floricane produces fruit and then dies. New primocanes are produced each year, so fruit production continues year after year.
Red and yellow raspberries produce numerous new canes from the base of the floricanes and from buds produced on the roots. The plants can spread in any direction. Thus raspberry patch is an apt name if the canes are not controlled through pruning.
Black and most purple raspberries produce primocanes only from the buds at the base of the floricanes. These clumps or hills remain in the original planting location.
Ever-bearing red raspberries, also called fall-bearing or primocane-fruiting raspberries, are able to initiate flowers during the first year. These cultivars produce fruit at the tips of the primocanes. During the second year, they can produce a summer crop on the same canes. One problem with this type of raspberry in Minnesota is that in areas of the state where the growing season is short, many fruits may be lost to early freezes. Pruning of fall-bearers may be adjusted to allow for both a fall and following summer crop, or to take just the fall crop.
Grow raspberries in a part of the garden that has good air circulation, good drainage, and full sunlight. Good air movement helps foliage dry faster, thereby reducing disease problems. Standing water will increase the likelihood of disease problems and death of the plants due to a lack of oxygen to the roots. Any well-drained soil is satisfactory for growing raspberries. Irrigation will be needed on a sandy soil, and even on more moisture-retentive soils during dry spells. Raspberry canes are sensitive to desiccation, so avoid a windswept site.
Text 2. Planting and Care
Early spring is the best time to plant raspberries. Purchase disease-free plants from a reputable nursery. Viruses can be readily transmitted into a planting through infected plants, and there is no way to cure the plants once they are infected. They can only be destroyed to control the spread of the virus.
The favored planting system for red raspberries is the narrow hedgerow. Set red or yellow raspberries every 2 to 3 feet, in rows at least 6 feet apart. Allow new primocanes to spread along the row but not wider than 12 inches. Wider rows invite fungal diseases because of slow drying conditions.
Set black and purple raspberries with 4 feet between plants and 8 feet between rows. Because these cultivars do not produce root suckers, they should be maintained in a hill system. The hill does not mean mounding the soil; it refers to the cluster of canes that develops from a single plant. Although black and purple raspberries do not send up new primocanes outside the hill, they can spread: the long, vigorous canes often arch down to the soil surface, where they may take root. Its important to keep the canes controlled and trellised.
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Raspberry plants need to be fertilized. When primocanes emerge in new plantings, scatter ¼ cup ammonium nitrate (33-0-0) around each plant. Once the planting is established, fertilize yearly by the first of May. Evenly distribute fertilizer such as ammonium nitrate (1/5 cup) or 10-10-10 (½ cup) per plant. Do not apply all fertilizer at the base of the plant, but spread it over the entire area.
Composted manure is a good source of nutrients and can be incorporated prior to planting at a rate of 3½ cu. feet per 100 sq. feet, to improve soil structure and provide nutrients. On established plantings, apply the same rate for plant nutrition.
Raspberries benefit from mulching. Good mulches for use in the home garden include leaves, lawn clippings, and wood chips or shavings, because they are usually free of weed seeds. Add ¼ to ½ cup of ammonium nitrate per bushel of wood shavings to speed decomposition and protect against nitrogen deficiency in the plants.
Plentiful water is important for raspberries from spring until after harvest. Because the root system is in the top two feet of soil, watering regularly is more beneficial than an occasional deep soaking. Raspberries need 1 to 1.5 inches of water per week from flowering until harvest. Use a rain gauge or check reported rainfall, and irrigate accordingly.
Raspberries will begin to bloom in late May or early June. Bumblebees, honeybees, and other wild bees are enthusiastic pollinators of brambles. The more bees working your planting, the more fruit you will harvest.
Unit V
STRAWBERRIES
