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GROWING berries RASPBERRIES


Growing a Raspberry Bush

A raspberry is a tart, edible fruit produced by a raspberry cane (Rubus idaeobatus). Raspberry canes are grown worldwide and have been cultivated into several different varieties. There are several named varieties of raspberries, so it is important to choose one that is right for your area.

 

Size

Raspberries are all similar sizes that can be maintained at approximately 5’-6’ tall at maturity.


Pollination

Raspberry canes are self-fertile and require no pollinator. While raspberry canes are self-fertile, generally a pollination partner will increase the size and quality of the harvest.

Pollination is important during your orchard planning as well, since you need pollinators to fly between your raspberry trees. The pollinizers should be planted no further than 50 feet apart, to ensure proper cross-pollination.


 


 

USDA Hardiness Zone

Raspberry bushes are hardy to USDA zones 4-9, unless otherwise noted This rating tells you the minimum winter temperature the plants typically survive when properly hardened off. On our web site you will find a USDA Hardiness Maps  which provides information on the average minimum winter temperature in your location, by zip code.


 

Chill Hours

Many plants native to locations that have cold winters have a Chill Hour requirement to ensure uniform waking up of flower and leaf buds in the spring. The chill hour requirement of plants varies by species, by cultivar, and sometimes by the level of dormancy achieved.

 


 

Where to Plant Your Tree

Raspberry bushed need to be planted where they receive at least 8 hours of direct sunlight measured in early summer (late June to early August). Sufficient sun exposure triggers the initiation of new flower buds for the next growing season, without which there will be no fruit. Fruit ripening and flavor development are also benefited by the carbohydrate production stimulated by the sun, as well as it’s heat.

Raspberries tolerate a wide variety of soils so long as they are well drained and moderately rich with a pH around 6.3-6.8. Improve your soil where you intend to plant by mixing an inch or two of plant based organic matter (manures are best for vegetable gardens), peat, or coconut coir into an area 1 1/2 to 2 times the diameter of the needed planting hole and up to a foot deep. A 2-4” deep layer of mulch (straw, leaves, or wood chips) applied after planting will continue to improve the soil.

Allow sufficient space for both the top of the tree and it’s roots when selecting the planting location. Refer to size descriptions for each variety, keeping in mind these are generally managed or pruned sizes, not maximum potential sizes. If you are planting an orchard be sure to include enough space between rows for transporting supplies in and fruit out.


 


 

Growing in Containers

Raspberry canes are good candidates for growing in containers.

To grow raspberry canes in a pot you need a container of at least 25 gallons. Larger is better, but make sure you have the ability and tools to move the pots heavy weight.

Do not use soil from your garden in the pot, instead use a potting soil mix with some added compost.

 


 

Care and Maintenance

Watering Your Tree

This is the most important and often the most difficult part of successfully growing plants. There are many factors, including the humidity, temperature, soil type, wind, and amount of direct sun that affect how much and how often water should be applied.

A general rule of thumb for plants in the ground is to ensure they receive an inch of water per week over the root zone. An inch of water is equivalent to about ¾ to one gallon per square foot of soil surface area. The typical three foot diameter planting hole would need 7 ½ to 10 gallons of water per week provided by rainfall or by the gardener.

Apply this water once a week, two times per week if soil is fast draining. This will of course depend on your own conditions and the plants you are growing! DO NOT water lightly each day because this results in a wet surface and dry root zone area. The soil should be moist but not soggy to a depth of about a foot for most growing plants. The top inch or two can feel dry, and the plant still be well watered. The trick is to have the water available where the roots are. In hotter and sunnier areas, a mulch of straw, bark, etc. can greatly ease the burden of summer watering. For plants in containers, water until the soil is saturated and water comes out of the drainage holes. Let the container dry until the soil is dry to the touch 1-2 inches down and the container is lighter in weight. A plant that has wilted can be receiving either too much or too little water.

In rainy areas like the Pacific Northwest most of the plants that we offer will need relatively little supplemental irrigation ONCE THEY ARE WELL ESTABLISHED in the ground and have had a chance to develop a good root system. However even here it is important to make sure plants have regular, deep watering during the first couple of growing seasons, and the first summer is especially critical. In drier areas, permanent irrigation is essential. Remember that you don’t want your trees to just survive, but rather to thrive. Make sure they get the water they need.

One method is through drip irrigation. We use half- inch flexible plastic pipe with punch-in emitters for trees in the ground. For each young tree, we use two emitters, spaced one foot from the trunk. The pipe can be put on the ground, under the ground with risers, or tied loosely from the trees. We use emitters that drip one gallon per hour. See drawing above. There are many different styles of drip systems, some controlled by timers and others by hand. Or, each tree can be watered with a hose deeply about once a week. Sandy soils will need more frequent watering than clay soils. For smaller plants, like strawberries or raspberries, soaker hoses work very well.

 

Fertilization

For good steady growth and high productivity, your trees need to have adequate amounts of various mineral nutrients. Some people are fortunate and have naturally rich fertile soil. Many soils, however, are deficient in some nutrient or another and use of fertilizers, organic or chemical, can be highly beneficial if you want your trees to grow well. If you have a large gardener orchardist can be well worth it to have your soil analyzed by a qualified laboratory so you know for sure just what your soil needs. Typically this might cost $30-$60, depending on how detailed an analysis you want. Unless you know what is available in your soil, you will not be able to supplement it properly.

Use an all-purpose or balanced fertilizer like the organic fruit tree and shrub fertilizer.  A couple of inches of well-rotted compost on the root zone can also be an effective fertilizer. A generous leaf or straw mulch around your trees will not only conserve moisture and help in weed control, but also keeps your soil healthy by building up humus, attracting earthworms, and supporting beneficial fungal organisms. This encourages young trees to be strong, healthy and productive. Use of concentrated products like chemical fertilizers or strong organics (for instance blood meal) is usually done from late winter through early summer. Applying fertilizer after early summer can encourage lots of soft new growth that is much more likely to be damaged by winter cold. Excessive use of fertilizer can increase disease problems on your plants and can even kill them. Use of too much fertilizer, whether chemical or organic, canals contribute to stream and groundwater pollution, so please try not to use more than your plants really need. As a general guide, if your plant is producing about one foot of new growth or more a year and has healthy looking foliage, it may not need much or any fertilizer.

 


 

Pests and Diseases

 

Spotted Wing Drosophila

Symptoms

Eggs are deposited 7-10 days prior to fruit ripening; holes in fruit, spotty molding, larvae in fruit, exuding berry sap, scarring.

 

Control Methods

Monitor with traps. Spinosad. Sanitation: In fall, adults feed on over ripe or split fruit (both vegetable and tree fruit) to prepare for winter.

 

Comments

Contact your local extension office for the most up to date information on spotting wing drosophila.

 

 

Leafhoppers

Symptoms

Stippling on leaf surface, small white jumping insects beneath leaves.

 

Control Methods

Pyrethrin or rotenone spray as needed. Insecticidal soap or soap/oil mix.

 

Comments

May also be seen on apple and pear.

 

 

Mites

Symptoms

Leaves stippled, very small crawling insects on the underside of leaves. Webbing often also present on underside of leaves or surrounding new shoot tips.

 

Control Methods

May develop resistance to Pyrethrin/rotenone spray. Release predatory mites. Insecticidal soap with ultra-light oil.

 

Comments

Usually not a problem if pesticides are kept to a minimum. Mites thrive during hot dry weather.

 

 

Cane Borers

Symptoms

New shoots wilt and die in spring. Cutting stem open reveals a white grub tunneling in stem.

 

Control Methods

Prune out and destroy affected shoots at once.

 

Comments

On primocane varieties you get some control by cutting canes to ground each fall

 

 

Botrytis

Symptoms

Ripening fruit covered with fuzzy gray mold.

 

Control Methods

Maximize sunlight and air penetration. Promptly remove diseased fruit. Don’t over water. Avoid wetting ripening fruit

 

Comments

Common in excessively wet or shady locations, especially with poor air circulation and overcrowded plants with berrries laying on the soil.

 

 

Viral Disease

Symptoms

Leaves may have yellow veins or other discoloration. Fruit crumbly, small or declining yields.

 

Control Methods

No cure, start over in a new location with virus free plants.

 

Comments

Plant only certified virus free stock. Use virus resistant varieties.

 

Root Rot

Symptoms

Roots are rotted and lack fibrous roots. Fruit stems are shortened, any berries remain small and wither. After hot dry periods older leaves may wither or look scorched or bronzed.

 

Control Methods

Plant resistant varieties. See Raintree catalog. Plant in new, deep, well-manured fertile soils, do not allow soil to become water-logged. Apply soil fungicides as a last resort.

 

Comments

Disease organisms can persist in the soil 7+ years, more if strawberries or brambles are present. Rotate fungicides to prevent disease resistance. Plant on mound if your soil is heavy or poorly drained.

 

Deer

Symptoms

Browsed shortened branches. Leaves are obviously munched on or plants are pulled up.

 

Control Methods

Fences or cages at least 8’ tall. Plastic mesh, electric, or woven wire fences.

 

Comments

At Raintree, an 8’ woven wire deer fence has worked best. Repellents don’t work consistently and only trained large dogs patrolling the perimeter are effective.

 

 

Bird

Symptoms

Fruits disappear or have gaping holes in them. Strawberries, blueberries, cherries and filberts are most susceptible but most fruits suffer occasionally.

 

Control Methods

Reflective Bird Scare Tape can work well. Bird netting. Cages.

 

Comments

Blue Jays start harvesting filberts when ready to pick, and so should you. Nuts dropped by jays are usually empty.

 

 

Vole/Mouse/Rabbit

Symptoms

Bark eaten in a band from soil level up to 8” and roots eaten too, usually in snowy areas with lots of mulch or tall grass at base of trees.

 

Control Methods

Keep mulch 4”-6” away from trunk. Keep grass short and 1’-2’ from trunk. Use vinyl tree guard wrapped around trunk until tree well-established.

 

Comments

Voles and mice will chew a couple inches above ground and also into the root system. Rabbits will chew up to 8” high, particularly apple trees.

 

 

Aphid

Symptoms

1/32 to 1/8” long pear shaped insects that multiply rapidly, espe- cially on the underside of leaves and on stems. Can be pink, green, black or white. Leaves show red blisters or are curled-down and stems turn black with sooty mold.

 

Control Methods

Natural predators like lady bugs and parasitic wasps often provide control. Knock aphids off with water spray. Spray with Pyrethrin, Rotenone, Insecticidal Soap, or delayed dormant oil. Control ants if they are also present.

 

Comments

Trees can tolerate some infestation. Monitor in late spring and summer. Control is more important on new trees. Grow plants that attract predators, i.e. dill or yarrow.

 

 

Ant

Symptoms

Numerous ants scurrying up and down the tree trunk; aphids, scale or mealybug present in large numbers, lots of sticky honeydew, perhaps sooty mold.

 

Control Methods

Find hill and apply pesticide. Apply Tangle Trap over 2-3” wide band of paper wrapped around trunk. Eliminate other pathways into tree.

 

Comments

Ants nurture and protect these insects in exchange for their sugary secretions. Insects may be difficult to control until the ants are controlled.

 

Brown Marmorated Stink Bug

Symptoms

Poking-type feeding damage followed by decay on fruits, nuts, berries and leaves. Deformity in the healthy tissue surrounding the dead tissue. Brown spots can show up in stored fruit.

 

Control Methods

Monitor with traps, some broad spectrum pesticides may work. Researchers are working on finding effective controls, but no info has been released yet.

 

Comments

BMSB over winters in groups in dry protected areas, such as houses. If you find them on or in your home use the vacuum, squishing releases their defensive stink.  See stopbmsb.org for more info. Feeding begins in spring when the weather warms up and continues until new adults go dormant for winter.

 

Rust

Symptoms

Lesions on the upper surface of the leaf, or on the fruit or stems, followed by orangish structures on the bottom side of the leaf, or on the fruit or stems, which produce spores.

 

Control Methods

Copper fungicide after harvest before fall rains and again in early spring for prevention of some\ rusts. Remove and destroy infected parts of the plant. If possible select resistant varieties. Many varieties have not been studied. Cedar-apple rust is a problem east of the Rockies.

 

Comments

Rust diseases require an alternate host, removing the host (within 900’ radius), applying fungicides, or removing infected parts may help. Check with your extension office to see what rust diseases in fruiting plants may be common in your area, and their alternate host.

 

 

Sunscald

Symptoms

Vertical splits in bark appear spring or early summer, usually on the south or east side of the tree. Disease or insect infestations may then occur.

 

Control Methods

Whitewash trunk and lower limbs with interior latex paint cut 50/50 with water each fall until bark has thickened. Avoid planting in frost pockets or where water collects in winter.

 

Comments

Injury occurs during pattern of warm days followed by freezing nights. Sap gets stuck in trunk, freezes, then rapidly thaws in the warm sun the next day, rupturing cells.