GROWING BLACKBERRIES Quick Links Before You Start Planting Planting Year Irrigation Fertilization Tissue Culture Bramble Plants Pruning Quick Reference BEFORE YOU START It is essential that, as you plan where you'll be planting your blackberries, you avoid soils where previous crops have included strawberries, brambles, potatoes, tomatoes, eggplants, or peppers. These crops may harbor soil pathogens, which will affect the health and performance of your new plants. Soil that has previously grown these crops should be crop-rotated for five to eight years with a non-Verticillium-susceptible crop, such as oat or wheat. If the soil is not well-drained, consider creating raised beds, other options for improving soil drainage or a different location with better soil drainage. Raspberry plants will not grow well or have as long a lifespan in soil that stays wet for too long due to root rot problems. For the best growth and productivity, send a soil sample to your Agricultural Extension for crop-specific pH and nutrient testing eight to ten (8–10) months before planting. Apply only what is needed for the crop under current soil conditions. Depending on soil conditions optimal pH range for brambles is about 6.0-6.8. Consider your climate and winter hardiness before purchasing. Your local Agricultural Extension Cooperative may be able to advise you about growing blackberry plants in your region. PLANTING Plant as soon as possible in the spring, after your soil has warmed to 50°F. Planting too early, in cool, damp soil, can delay development or cause roots to rot. Planting at the correct depth is essential. Plant tissue culture plugs one-half to one inch (½–1") deeper than the soil level of the plant. Your planting rows should be measured and maintained at no more than a twelve to eighteen inch (12–18") width. Aisles should be 8–10 feet wide, depending on machinery. Do not fertilize at planting. If you do not optimize the soil before planting, you may incorporate ½ lb.– ¾ lb. of 10-10-10 per 100 sq. ft. at least two to three (2–3) weeks before planting. Alternatively, wait until the plants are well-established and then side-dress with 10-10-10 to maintain vigorous growth. Tailoring fertilizer application is best for the plants. Irrigate well soon after planting. Maintain good moisture levels until the plants are well established or for four to six weeks but take care not to overwater. Use care when applying herbicide to TC plug plants. We have had good results using four (4) lbs. per acre of Devrinol 50W. In our experience, other herbicides will damage these plants. PLANTING YEAR New growth may not appear for five to six (5–6) weeks. Expect most, if not all, new growth to come from the roots. If you want to check for root development after six to seven (6–7) weeks, dig very gently starting two to three inches (2–3") away from the base. Be careful not to damage delicate new roots or sprouts that have not yet broken the soil surface. If the plants are not leafing out or sprouting new growth from the roots after seven to eight (7–8) weeks, call us. IRRIGATION Water thoroughly right after planting and maintain good soil moisture until plants are well established. The plants should then receive one to two (1–2) inches of rainfall, or the equivalent, each week throughout the season, depending on the drainage rate of the soil, weather conditions, and if plants are developing flowers or fruit. In some circumstances, plants may need up to 2 gallons per plant every other day. Roots need time to breathe. Watering every day is too much under most conditions; one to three times per week is usually sufficient. Regularly check soil moisture 1-3 inches deep to assess the need to irrigate. We strongly encourage the use of drip irrigation as it adds water directly to the root zone and does not wet the plants, flowers, and fruit. WEED CONTROL/MULCHING Mulch is a protective layer of material applied on top of the soil. Mulching can bring numerous benefits to your plantings, including providing micronutrients that enhance topsoil fertility, increasing organic matter, and improving soil water-holding capacity by reducing evaporation and moderating soil temperature. Additionally, mulching increases the number of fine roots. We recommend lightly mulching with weed-free straw during establishment to help control weeds and retain moisture. Leaves or grass clippings are not recommended, as they can mat, smother plants, and harbor pests. Do not apply a deep layer of mulch, as it will impede the growth of new canes, which need to develop every year. Do not mulch brambles beyond the first year. Regular manual weeding will be necessary. Weeds and crops compete for the same resources, including sunlight, water, and nutrients. When weeds deprive a crop of these resources, the crop yield is negatively impacted. Some weeds can also carry crop pathogens or serve as hosts for damaging insects. FERTILIZATION Do not fertilize when planting. Commercial growers should have soil pH and nutrients tested the season before planting, and every year or two for the best and most consistent growth and productivity. In the absence of early soil test results, you may thoroughly incorporate a light amount of fertilizer at least two (2) weeks before planting or wait until new transplants are well established. Growers may apply ½ lb. - ¾ lb. of 10-10-10 fertilizer per 100 sq. ft. early each spring, and an additional one (1) lb. of 10-10-10 fertilizer per 100 sq. ft. in mid-summer, or tailor the fertilizer application based on current soil test results and recommendations. Larger growers could use 500 pounds of 10-10-10 per acre, or fine tune applications according to soil test results. Additional fertilizer applications may be necessary, depending on weather and/or leaching conditions. Adjusting the pH and nutrient levels according to soil testing and foliar testing is most efficient and effective. Don’t fertilize after July 1st, as it encourages tender growth that will be more susceptible to winter injury. PRUNING Primocane-Bearing (Fall-Bearing/Everbearing) Primocanes require pruning during the growing season. Pinching or snipping the tips in mid-summer (tipping) makes plant height manageable and increases yield potential. When primocanes reach twelve to fifteen inches (12–15") in height, tip the top one inch (1") of the primocanes to encourage the cane to grow lateral branches. Tips are tender and can be easily removed by pinching between your thumbnail and finger or with pruning shears. This is called soft tipping. This process increases the places where the plant can produce fruit. Do tipping and pruning when plants are dry. Cutting later creates larger wounds and leaves the plants more vulnerable to disease, so you might consider applying a fungicide after making such cuts. As the lateral branches reach thirty inches (30"), pinch or snip one inch (1") of the tips. This process stimulates earlier fruit development, increases yield, and maintains a convenient plant height for easier management and harvest. In warmer climates, the initial soft tipping could be done when the plants are 3-4 feet tall with an optional second soft tipping done when the laterals have reached 12-18 inches. You may experiment with tipping heights or consult your local Agricultural Extension to adjust optimal tipping heights in your region or climate. Keep no more than 6-8 primocanes per plant. Single Cropping Canes translocate energy (carbohydrates) to the roots over the winter, which the plants can use for growth the following year. Cut all canes at the base as close to the ground as possible in late winter, before the emergence of buds. These should not be allowed to grow arms (laterals). All new growth should come from the roots. This process allows the plant to focus all its energy on producing strong new primocanes in the spring. Ensure that all cut canes are removed from the area to lessen disease pressure. Primocanes will produce fruit in late summer and fall, depending on location and weather conditions. Double Cropping Summer Tipping Primocanes require pruning during the growing season. Pinching or snipping the tips in mid-summer (tipping) makes plant height manageable and increases yield potential. When primocanes reach twelve to fifteen inches (12–15") in height, tip the top one inch (1") of the primocanes to encourage the cane to grow lateral branches. Tips are tender and can be easily removed by pinching between your thumbnail and finger or with pruning shears. This is called soft tipping. This process increases the places where the plant can produce fruit. Do tipping and pruning when plants are dry. Cutting later creates larger wounds and leaves the plants more vulnerable to disease, so you might consider applying a fungicide after making such cuts. As the lateral branches reach thirty inches (30"), pinch or snip one inch (1") of the tips. This process stimulates earlier fruit development, increases yield, and maintains a convenient plant height for easier management and harvest. In warmer climates, the initial soft tipping could be done when the plants are 3-4 feet tall with an optional second soft tipping done when the laterals have reached 12-18 inches. You may experiment with tipping heights or consult your local Agricultural Extension to adjust optimal tipping heights in your region or climate. Keep no more than 6-8 primocanes per plant. Summer pruning Floricanes can be removed in the summer, immediately after harvest. This allows resources to be spent on canes that will produce for you in the future and opens the row to better air circulation and sun exposure. Winter Pruning In late winter, remove the spent floricanes from the previous year if you didn’t do so right after the summer harvest. These dead canes are tan or white. Cut at the base of the canes, as close to the ground as possible. Keep 5-8 of the reddish maroon canes, as these are the previous year's primocanes that have overwintered and become floricanes. Use sharp, clean bypass pruners for an easier job. Remove any portions at the tops of the canes that fruited the previous year. This fruited cane portion is now dead, tan in color, and will not produce fruit again. Cut 2-3 inches below where the dead portion ends. Sharp, clean bypass hand pruners work well for this task. Cut off anything damaged or broken. Cut lateral branches back to a manageable length of twelve to eighteen inches (12–18"). Trim back any dead portions that remain. These floricanes will flower and fruit in the summer. Floricane-Bearing (Summer-Bearing) Blackberries Primocanes require pruning during the growing season, called tipping. Tipping makes plant management easier and increases yield potential. In midsummer (typically late June and July), when primocanes (first-year canes) reach five to six feet (5–6') in height or six inches (6") over the top wire of the trellis, pinch or snip the top ¾ inch to 1 inch. This is called soft tipping and is preferred. Tipping stops terminal growth and forces growth into the development of fruiting laterals. Thin the primocanes to six to eight (6–8) canes per three feet (3') in a row or per hill/plant. Do tipping and pruning when plants are dry. Cutting later, when canes have a larger diameter, creates larger wounds and leaves the plants more vulnerable to disease, so you might consider applying a fungicide after making such cuts. Do not prune floricanes before the fruiting season unless diseased or damaged. When the fruiting season ends, cut out spent fruiting canes (floricanes) at the base, as close to the ground as possible. Removing spent floricanes provides more space and energy for new primocanes to grow. Do not cut the primocanes to the ground; they get tipped, overwinter and develop flowers and fruit the following season. In late fall, cut laterals back to six to eight inches (6–8"). If using the staked management system, prune canes to the height of the stake and follow the instructions above. TRELLISING BLACKBERRIES Trellising brambles is one of the most important cultural practices, and we recommend trellising all brambles. A trellis keeps canes upright and fruit off the ground, making picking far easier, reducing wind damage, and maintaining good aeration throughout the planting, which helps control disease and Spotted Wing Drosophila pressure. 3- OR 4-WIRE TRELLIS For blackberries, we have been successful using a 3- or 4-wire trellis, which supports three or four wires, approximately one foot apart. To construct a 3- or 4-wire trellis, install an 8-10-foot-long metal fence post about 2.5-3 feet deep. Run galvanized high-tensile wire along the row at the following heights: 2.5', 3.5', 4.5', and 5.5'. Attach the main canes to the wire with a clip or a slightly loose twist tie. Posts should be spaced 15-25 feet apart along the row. “T” and “V” TRELLIS These trellis types are acceptable for blackberries as well, but training and pruning can be a little labor intensive. ROTATING CROSS ARM TRELLIS OR SHIFT TRELLIS Trellising system often used in cooler regions where it is more challenging to overwinter floricane-ripening blackberries. The trellis has several wires and canes are trained in a certain way to allow the trellis and canes to be rotated to the ground for covering during the winter months. A bonus is that fruiting laterals grow to one side of the trellis early in the season, making harvesting faster and easier. HARVESTING AND STORAGE Harvest blackberries two to three times per week. We recommend picking fruits in the morning when berries are firm and before temperatures warm. Avoid harvesting fruit in the rain or when the fruit is wet. When picking and handling the fruit, take care not to bruise or crush the fruit. As soon as possible after harvest, cool the fruit. The ideal cooler temperature is between 33°F and 35°F, with a relative humidity of 90% to 95%. For local markets, including pick-your-own or roadside operations, it may be more advantageous to pick fruits after they have achieved a dull appearance, as they will have fully ripened and typically possess a high sugar content. Blackberries do not continue to ripen after they are picked. At the dull skin stage, berries have a decreased shelf life but maximized flavor. For shipping, research suggests that it is beneficial to pick the berries when the skin is shiny, resulting in a longer shelf life but a less sweet taste. Heat stress negatively impacts flowering, fruit size, and fruit quality.
