*Editor's note: Growing Raspberries in Your Home Garden is being revised. This text is taken from a similar publication, Growing Berries on the Oregon Coast: Raspberries and Blackberries by Cassie Bouska, Emily Dixon and Bernadine Strik. The information here applies to Western Oregon.
If you are reading this publication for the first time, we recommend you first read Growing Berries on the Oregon Coast: An Overview (EM 9177). It includes general information on site selection, soils, irrigation, mulching, nutrient management, and considerations specific to the coastal environment.
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Raspberries are among the most delicious and delicate of berry crops. Raspberries include red-, yellow-, black- (also called blackcaps), and purple-fruiting cultivars. Raspberry-blackberry hybrids (e.g., ‘Boysen’ and ‘Logan’, also known as “boysenberry” and “loganberry”) are trailing blackberries.
Raspberries have an unusual growth habit. The plants have a perennial crown (plant base) and root system, and biennial aboveground canes. There are two types of fruiting habits:
Raspberries can be distinguished by their fruit. They produce an aggregate fruit of many drupelets (the individual sections of the berry, each of which encloses a seed). However, when raspberries are picked, the fruit comes off the receptacle (white central core that stays on the plant) and the berry is hollow inside.
All raspberry types produce primocanes from the crown and the base of old canes each year. Red raspberries can also produce new primocanes from buds on the roots, and so the plants spread out from the place they are planted. Raspberries that are floricane-fruiting produce fruit in June and July, depending on the cultivar. The fruiting season of primocane-fruiting raspberries is from early August until the first frost on the new primocanes, and June and July on the floricanes, depending on the cultivar.
Some raspberry plantings can produce for over a decade, so select an ideal planting location. Even black raspberries, which tend to succumb to disease after four to eight years, benefit from good site selection. Direct, full sun is best for good fruit production. Raspberry plants can tolerate partial shade, but yield and fruit quality may be lower. Raspberries prefer well-drained, fertile, loam soil with moderate water-holding capacity. Raspberry plants are sensitive to wet, heavy soils. This sensitivity increases their vulnerability to root rot. In addition, raspberries are also susceptible to verticillium wilt, a soil-dwelling fungal disease. Avoid planting raspberries in sites where other verticillium-susceptible crops (such as strawberries, kiwifruit, potatoes, tomatoes, peppers or eggplant) have been planted in the past five years. Crop rotation will also disrupt other pest and disease cycles in the field.
Wind can damage raspberries. Windbreaks (such as a row of trees or shrubs) can provide protection, but be careful where you establish them to avoid competition with the berry crop. See Windbreaks for Fruit and Vegetable Crops listed in “For more information.”
Raspberries require soils with a pH range of 5.6 to 6.5. Test the soil six months to a year before you plant to give yourself enough time to modify the soil pH or add nutrients, if required. For more information about soil testing, see Analytic Laboratories Serving Oregon (EM 8677), A Guide to Collecting Soil Samples for Farms and Gardens (EC 628), and Soil Test Interpretation Guide (EC 1478). If the soil is too acidic (the pH is too low), add lime to the soil as recommended by the soil analysis to raise the soil pH to the upper end of the ideal range. See Applying Lime to Raise Soil pH for Crop Production—Western Oregon (EM 9057) for more information. In general, if your soil pH is too low for berry production, incorporate finely ground dolomitic limestone at a rate of approximately 5 to 10 pounds per 100 square feet (1.1 to 2.1 tons per acre). You may also use high pH composts to add organic matter and increase soil pH (see Growing Berries on the Oregon Coast: An Overview (EM 9177). These amendments should be incorporated about a year prior to planting as it takes time for the soil pH to adjust after the addition of lime. See Table 1 for soil nutrient ranges for raspberries.
Raspberries are very sensitive to poor drainage. Because of their large root system, raspberries benefit when planted in well-drained soil that is at least 2 (and ideally 3) feet above the water table. Usually, raised beds are required to grow raspberries to ensure adequate drainage. Ideally, provide a well-drained, fertile, loam soil with some water-holding capacity. This will ensure your raspberry plants will be more vigorous and produce more fruit, regardless of type or cultivar. More detailed information on drainage and options for improvement is available in Growing Berries on the Oregon Coast: An Overview (EM 9177).
All types of raspberries are self-fruitful, so only one cultivar is needed for pollination and fruit production. See Table 2 for recommended cultivars for each type of raspberry. Primocane-fruiting (“fall-bearing”) cultivars fruit quite late, so they may need to be grown under tunnels for consistent fruit production during the late summer and autumn rains. Purple raspberries are not commonly grown in Oregon but may be a good addition to the home garden or a U-pick farm because they are excellent for processing into jams or pies. For detailed information on cultivars within each type, refer to Raspberry Cultivars for the Pacific Northwest (PNW 655).
Purchase certified disease-free plants from a reputable nursery. Do not propagate or move “suckers” from an older, established planting. Raspberry plants are susceptible to root rot and viruses that can be introduced to your planting by noncertified plants. Raspberry plants are sold as either bare-root plants (short cane section with roots attached) or as potted plants, typically propagated using tissue culture. If they can’t be planted immediately, bare roots should be heeled in by covering the roots with moist soil or sawdust. Begin planting as soon as you can work the soil in the spring. Dig a shallow hole that is large enough to accommodate the roots. Roots from bare-root plants should be spread out and the highest point of attachment of roots to cane should be 1 to 2 inches below the soil. Cover the planting hole with soil and firm the soil to remove air pockets. Water thoroughly and cut the canes of newly planted bare-root plants to 6 inches, if they are longer. Small, tissue-cultured plants need to be cared for in the same way as a tender vegetable transplant. Water them frequently until the plants are established. Larger, potted plants are a little less tender, but good water management is still important.
Only primocane-fruiting types will produce a small crop in the planting year. All types will produce a “baby” crop the next year, and the third year they will be in mature production.
You can grow floricane-fruiting raspberry plants in a hedgerow (solid row of canes) or a hill-system (as individual plants) (Figure 1). Primocane-fruiting raspberry plants should be grown in a hedgerow (Figure 2).
Rows of raspberries should be spaced 8 to 10 feet apart and plants 2 (primocane-fruiting types) to 2.5 feet (floricane-fruiting types) apart. Keep any primocanes that emerge in the row area between plants. Maintain the row width to about 6 to 12 inches by removing any primocanes that emerge outside this area by pruning or rototilling. If you allow wider hedgerows, management tasks such as weeding, pruning and harvest can be difficult and disease can become more of a problem due to the dense canopy.
The “hill” in a raspberry planting is the cluster of canes that develops around a plant. Rows should be 8 to 10 feet apart and in-row plant spacing should be 2.5 feet. Individual hills should be restricted to a diameter of 1 to 1.5 feet. Remove all newly emerging primocanes that develop between the hills or in the aisles. In vigorous plantings, the primocanes may be thinned in winter to 6 to 8 canes per hill.
Black and purple raspberries are vigorous and should be planted with 8 to 10 feet between rows and 3 to 4 feet between plants within the row. These types only produce new primocanes from the crown and remain as individual plants.
Most raspberries require trellising. Summer-bearing raspberry plants need a permanent trellis for support. Set treated wooden or metal posts at each end of the row (3 to 4 inches in diameter and 6 feet above ground) (Figure 3A). Set metal T-style posts every 15 to 20 feet in the row. Training is easiest with two sets of two high-tensile wires (generally 12-gauge) — one set near the top of the trellis (about 5.5 to 6 feet from the ground), attached directly to the posts, and one at about knee height, attached so you can remove them (for example, by using hooks, as shown in Figures 3B and C). This design will allow you to lift the lower wires out over the growing primocanes to pull them into the row and prevent damage. Use a wire-tightener in each of the top wires. You can also use a single, high-tensile wire at the top of the post and install a cross arm on each post to support the lower wires. The cross arm should be about 12 to 18 inches long, and nailed or bolted (Figure 3D).
If primocane-fruiting raspberries are grown for only a primocane crop (late summer to autumn fruit harvest), you can use a temporary support structure, such as a simple “T” trellis with a 1.5-foot-wide cross arm attached at about knee height. The T can be made using rebar with twine or wire strung down each side of the row to support the canes. This type of trellis is also commonly used for black raspberries (Figure 4).
When soil in the garden is not well suited for berry production (even after you make all possible amendments) or space in the yard is limited, you can grow berry plants in containers on a deck or balcony. Choose a site that has good sun exposure. Because containers have a relatively low volume of soil, these plantings require careful monitoring and care, especially when watering and fertilizing. Choose a container and a potting mix that are well suited for the plant. Follow the planting, fertilizing and pruning recommendations described in this publication.
The best types of raspberries for container production are primocane-fruiting cultivars, which produce two crops per season. Since raspberry plants are relatively deep rooted, they require a deep pot (2 feet deep or a 20- to 30-gallon size) and careful pruning to ensure the plant doesn’t get too large for the container. Thin the plant to no more than 4 primocanes (and 4 floricanes when over-wintering) per pot (see “Pruning and training”). It’s very important that the potting mix and the container drain well if you want to be successful with container-grown raspberries. A recommended soil mixture is one part perlite, one part finely ground fir bark, and two parts garden or potting soil; yard centers may sell a similar mix in bulk. If desired, slow-release (sulfur-coated) fertilizer can be mixed into the potting mix at a rate of 8 cups per cubic yard of medium.
Raspberry plants, like all berry crops, need adequate water to thrive. You can irrigate your crop by hand, or with sprinklers or drip systems — whatever works best for you. The important thing is to make sure that adequate moisture is getting to the root zone. For more information on irrigation, see Growing Berries on the Oregon Coast: An Overview (EM 9177).
In all berry cropping systems, drip irrigation is ideal. Raspberries can be irrigated with a single line of drip irrigation per row with half-gallon emitters placed every 18 inches. Established raspberry plants typically need from 1 to 1.5 inches of water per week during the growing season.
A mulch can help control annual weeds, conserve soil moisture, and depending on the type of mulch, provide a source of nutrients. Be careful to not bury the raspberry crowns as this can lead to crown rot or plant death. Deep straw is not recommended as it can bury the crown and lead to increased vole or rodent activity, which can damage the plants. For more detailed information on mulches, refer to Growing Berries on the Oregon Coast: An Overview (EM 9177).
When fertilizing new plantings, plan to divide the total required nitrogen (N) into three equal portions, the first starting two weeks after planting, the next one a month later, and the last a month after that. Spread the fertilizer evenly down the row area. Fertigation can also be used in raspberries. See the Caneberry Nutrient Management Guide (EM 8903) for more information.
In the planting year, fertilize floricane-fruiting raspberries with a total of 2 ounces N per 10 feet of row (50 pounds N per acre), primocane-fruiting raspberries with 2.5 ounces N per 10 feet of row (70 pounds N per acre), and black raspberries with 0.5 ounces N per plant (45 pounds N per acre).
Well-balanced fertilizers, such as 16–16–16, some similar types of inorganic fertilizer, and some organic products, work well for raspberries. See Growing Berries on the Oregon Coast: An Overview (EM 9177) for more information on fertilizing berry plants.
Fertilize floricane-fruiting raspberries with a total of 2 to 3 ounces N per 10 feet of row (50 to 80 pounds N per acre) per year. Fertilize primocane-fruiting raspberries with 3 ounces N per 10 feet of row (80 pounds N per acre).
Divide the fertilizer into two applications, applying the first in late March to early April, just as the new primocanes start to grow, and the other in late May to early June. Primocane-fruiting raspberries may require an additional 0.5 ounce N per plant or about 1 ounce per 10 feet of row (25 pounds N per acre) in mid- to late July to ensure there is adequate nutrition to accommodate the late- fruiting period.
Broadcast the fertilizer over the soil surface in the row area (about 2 to 3 feet wide, centered on the row). Irrigate immediately after fertilization. If you use manure applications (generally in autumn or early winter to a depth of about 2 inches), try reducing the fertilizer N by half and monitor plant growth to see if additional fertilizer N is needed. Fresh manure is not recommended as it is high in salt content and can burn plants.
If N is fertigated, divide the total recommended rate into equal amounts and make weekly or bi-weekly applications from early April through July, depending on the type of raspberries grown.
A well-managed plant should have healthy green leaves with good primocane growth (a good number per plant and a normal length for the cultivar being grown). Pale green or yellow primocane leaves could indicate N deficiency. Primocanes that are too tall (e.g., 10 feet for raspberry), thin (less than 0.37 inch), or with long internodes (distance between leaves) indicate an excess of N fertilizer.
Monitor soil pH every few years and add lime in autumn to maintain the soil pH within the desired range for raspberries.
Raspberries are self-fruitful, so only one cultivar is necessary for fruit production. In many home gardens and on small farms, there are often sufficient native honey and bumble bees to ensure good pollination. However, for good fruit set in larger plantings, place two to four hives per acre in a location that will ensure good bee activity. Keep in mind that pollination is affected by wind. Place hives in the field no earlier than when, on average, 5% to 10% of each plant is in bloom. For more information, see Nurturing Mason Bees in Your Backyard in Western Oregon (EM9130) and Evaluating Honey Bee Colonies for Pollination (PNW 623).
Pick regularly. This not only helps ensure you collect berries at their optimal ripeness but also reduces insect pests and diseases that are more prevalent on overripe fruit. During periods of hot or rainy weather, you may need to pick more frequently. Try to avoid picking when fruit are wet from dew, fog, or rain and don’t wash it before storage. Wet fruit will decay faster. Refrigerate fruit immediately for optimal length of storage and quality.
Ripe raspberry fruit will separate easily from the receptacle. Hand harvest with a gentle pull on ripe fruit (Figure 5), ensuring the fruit are not squeezed, which reduces firmness and shelf life. In general, pick raspberries every 3 to 4 days, depending on the cultivar and the weather. Pick into shallow containers so fruit does not crush.
Hand-picked, summer-bearing red raspberries can be expected to yield 18 to 27 pounds per 10 feet of row (4 to 6 tons per acre). Primocane-fruiting cultivars and black raspberries will yield slightly less.
For summer-bearing red raspberries, do not prune or tip (remove the top 3 or 4 inches) the primocanes during the growing season. You may remove any primocanes that grow outside the in-row area by cutting them off at soil level with loppers or by tilling beside the raspberry row. Small, commercial farmers may use registered contact herbicides to burn back the early emerging primocanes and lower fruiting laterals (primocane suppression).
After fruit harvest, the dying floricanes (Figure 6A) need to be removed by pruning them at the crown, near soil level (Figure 6B); this is called caning out. Cane out immediately after harvest (Figure 6C) if there are cane disease issues, or wait until canes are fully dead by pruning them in autumn. Pruned canes can be chopped up between the rows using a flail mower, returning organic matter to the soil or be removed and composted. In winter (December through February), prune the remaining primocanes by removing weak, broken, diseased, and insect-damaged canes. Remove any primocanes that are outside the 6- to 12-inch-wide hedgerow by pruning or tilling. If you are growing plants in the hill system, leave all the healthy primocanes in the hill area and remove any that are growing between hills or plants and outside the row area. Shorten the primocanes to 6 feet and tie them to the trellis (Figure 7A) either as bundles of canes or individually. For a higher yield (although smaller fruit size), slightly tip the canes in late winter to remove very thin growth. Tie the cane bundle to the top wire and loop it down, tying the end to a lower training wire. This is called arc-cane training (Figure 7B).
Grow primocane-fruiting raspberries in a hedgerow. Maintain the hedgerow to a width of 12 to 18 inches by tilling or hoeing any primocanes outside the row (Figure 14). If you are producing two crops (floricane and primocane) per season, remove the dying floricanes soon after you harvest the early summer crop (following the instructions described for summer-bearing types) or the following winter. The late summer-autumn crop will be produced on the top portion of the new primocanes. In winter, remove the dead tips of the canes that fruited in late summer; the base of these canes will fruit in early summer as floricanes (Figure 8). Remove any weak or damaged canes and narrow the row. If you are only growing these cultivars for a single crop in late summer, cut all the canes to just above ground level in late winter (March) (Figure 9). Maintain your row width at 12 to 18 inches when the new primocanes emerge.
If you have the space, it is best to grow primocane-fruiting types for only the late-summer primocane crop and grow floricane-fruiting types for the early to mid-summer floricane crop. Summer-bearing types have better fruit quality and higher yield than primocane-fruiting types.
For black and purple raspberries, tip the primocanes in late spring or early summer by removing the top 3 to 4 inches. Top them to a height of about 3 feet. You will need to go over the planting multiple times throughout early summer to catch all of the primocanes. These types produce productive lateral branches when they are topped (Figure 10). Remove dying or dead floricanes anytime from after fruit harvest through autumn; some commercial growers do not remove these dead canes due to labor costs, but this can increase pests and disease in the canopy. In winter, remove any damaged or diseased wood and shorten the lateral branches on the primocanes to 1.5 to 2.5 feet (Figure 11). In larger plantings, this can be done by mechanically hedging the rows using sickle bars.
Weeds compete with the berry plants for water, nutrients and light, so it is important to keep weeds out of the row. A mulch layer of sawdust or bark can help control weeds, particularly annual ones.
In black raspberries, you can use a perforated, polyethylene ground cover (“weed mat”) as a mulch for weed control in the row (Figure 12). This type of mulch doesn’t work well in red raspberries that produce primocanes from the roots because the weed mat inhibits new primocane growth. Install the weed mat prior to or just after planting by placing it over the row or raised bed and overlapping the edges. Stake down the edges or use soil to hold them down. Cut an “X” or a 6–inch-diameter circle in the plastic where each plant will be set, and plant through the holes. You can also lay down the weed mat just after you plant, feel for the plants under the plastic, and then to carefully cut the holes. Even though weed mat is perforated, it is best to use drip irrigation underneath it to ensure plants get enough irrigation water, particularly when grown on raised beds.
For chemical weed control, check with your county office of the OSU Extension Service or a garden or farm supply store for herbicides registered for use on raspberry plantings. Not all herbicides are registered for all crops.
You will also want to manage weeds between the rows (the aisles) so that they do not spread into the area with your berry plants. The aisles can be cultivated and kept as bare soil or seeded with grass or another cover crop. If you are growing relatively few berry plants in your home garden, you may find it more practical to use other materials between your rows, such as bark mulch, wood chips, or straw. See Commercial Red Raspberry Production in the Pacific Northwest (PNW 598) for more detailed information on using cover crops in berry production systems.
Refer to the PNW Plant Disease Management Handbook for more detailed information on weed control and specific weeds.
The most important insect pest in berry production is the spotted wing drosophila (SWD; Drosophila suzukii). It was introduced to the mainland United States in 2008 and has rapidly become a major problem in all berry crop production areas. This vinegar fly looks like a commonly seen fruit fly. However, the female lays eggs in developing fruit (generally after it first develops some color). The resultant larvae feed inside the berry while the fruit are ripening. Populations of SWD build up during the season, so late-fruiting cultivars are more prone to this pest. For more information on how to control and manage this insect, refer to the SWD publications listed under “For More Information.”
Check with your local office of the OSU Extension Service for control recommendations if insects become a problem. Control methods are also outlined in the PNW Insect Management Handbook. Control options vary for commercial small-acreage farmers (with commercial pesticide applicator’s license) and home gardeners.
Insect problems for raspberries include root weevils, raspberry crown borer, leaf-roller larvae, spider mites, and aphids.
Control methods are outlined in the PNW Plant Disease Management Handbook. Control options vary for commercial small-acreage farmers (with commercial pesticide applicator’s license) and home gardeners. Check with your local office of the OSU Extension Service for control recommendations if diseases become a problem.
Raspberries are extremely sensitive to wet soils. Root rot, a soil-borne disease aggravated in wet, heavy soil, can be a major problem. Although most cultivars are susceptible to root rot, there are some that are tolerant or even resistant. Check Raspberry Cultivars for the Pacific Northwest (PNW 655) for information on cultivar susceptibility to root rot. Black raspberries are also especially susceptible to verticillium wilt. Powdery mildew, yellow rust, and anthracnose can also be problem in some raspberries.
To learn more about growing individual berry crops on the Oregon Coast, see these other publications in the series: