With good preparation and proper care, most berry species can be grown in the Central Valley area, including blackberries, raspberries, and blueberries. Cane berries are very manageable if they are trellised and pruned correctly, and if their roots are contained when necessary, such as with red raspberries.
Many Central Valley residents don’t realize that the blueberries (Vaccinium corymbosum) can be successfully grown here. The varieties grown here are the southern highbush types; northern highbush varieties do not tolerate our hot summers and low winter chilling. All varieties are self pollinating but fruit set will increase and berries will be larger if two varieties are planted together. Blueberries are deciduous shrubs that grow to 6 feet or taller.
Blackberries, Boysenberries and Raspberries
Several berry types, both thorny and thornless, are often classified as blackberries and are sometimes called dewberries. The main types are western trailing types (Rubus ursinus) and erect and semi-erect cultivars (no trellis required), which are being developed mainly for cold climates. Most trailing varieties root at the tips of shoots if they come in contact with the soil. Blackberries.
One of the oldest and most popular varieties is ‘Ollalie’, which is actually a cross between blackberry, loganberry, and youngberry. It is large and glossy black at maturity and is slightly longer and more slender than the boysenberry. ‘Thornless Black Satin’ has a heavy crop of large, elongated dark berries and are good for fresh eating or cooking. Another good variety is ‘Black Butte’. ‘Marion’ berry is widely grown in the Pacific Northwest; it is very spiny and is used mostly for canning, freezing, pies, and jam. ‘Loganberry’ is a cross between wild blackberry and raspberry and is available as thorny or thornless. It ripens early and has large, elongated, dusky red berries that are juicy and acidic, and it can be used for fresh eating, frozen, or preserves. ‘Tayberry’ originated in Scotland and is a cross between blackberry and raspberry. It has thorny canes that bear large, narrow reddish black fruit with a delicious tart flavor.
The boysenberry, which originated in California, is reddish-black and very large at maturity. Its aroma and sweet-tart flavor are suggestive of raspberries. The vines are thorny and vigorous. The nectarberry and thornless youngberry are very similar, but the youngberry is almost seedless.
Raspberries (Rubus idaeus) are largely grown in the relatively cool, marine climate of the Pacific Northwest. In the Central Valley area, most varieties grow best with some afternoon shade, however, ‘Oregon 1030’ and ‘Bababerry’ prefer full sun. Red raspberries have invasive roots and will spread unless contained by borders, or unless unwanted shoots are hoed in the spring. Three types of raspberries are available: summer bearing, everbearing, and black. Summer bearing varieties, like blackberries, produce new canes from the ground at the same time that they bear fruit on last year’s canes. Everbearing or fall-bearing varieties produce flowers and then fruit on the mature tips of current season’s growth, starting in mid to late summer and continuing through the fall. If not pruned, they would then overwinter and produce a second crop on the lower half of the canes the following summer. Black raspberries have dark fruit that are produced on shrubs, so they need no trellis.
Berries, like most woody plants, will grow on most soil types, provided that the soil is porous and well drained. However, raspberries produce best on sandy loam soil. All soils benefit by the thorough incorporation of well decomposed organic matter. The best organic amendment is compost that has undergone a thorough aerobic decomposition process. If undecomposed material is used, such as manure or leaves, do not plant for at least one or two months before planting to allow it to break down. Any organic amendment should be thoroughly incorporated into the soil, since buried pockets of organic matter may become toxic to roots by not decomposing properly.
Most berries are shallow rooted, and the roots occupy a space about 3 or 4 feet wide. Therefore, the soil should be dug this wide and at least a foot deep; two feet would be better if drainage is poor. If hardpan is present in the top 2 feet of soil, it must be broken up or else roots will not grow and water will not drain properly. Alternatively, use raised beds or mounds to provide adequate soil for root growth.
Like most woody plants, berries grow best in a soil with a pH of about 6 to 7.5. However, blueberries require a much more acidic soil – about 5.0 to 5.5. To acidify the soil, incorporate soil sulfur (not dusting sulfur) in the top 8 in. at a rate of about 3 to 7 lbs. per 100 square feet. The amount to use depends on soil texture (use higher rate in clay soils, lower rate in sandy soils), calcium carbonate (lime) content (use higher rate where soil analysis shows high levels), and existing pH. Rototill the sulfur and compost in a strip about 3 or 4 ft. wide in the row in the top 6 in. of soil. Test the soil at planting and every year with a kit available at local nurseries to be sure it remains acidic. Fertilize with an acidic fertilizer, such as ammonium sulfate, and/or side dress or lightly incorporate additional sulfur later.
Planting and Spacing
Cane berries are often planted during the dormant season (mainly December and January), but potted vines can also be planted in spring or summer. All berries should be planted on a small mound or berm if the soil is poorly drained. Bare root blackberries should be set at the same depth they were growing before transplanting, whereas raspberries should be set about an inch lower. Roots should be spread as much as possible and the soil firmed well around them. If the soil is dry, irrigate after planting, but if the soil is wet, no irrigation is necessary. After planting, cover the soil with plenty of mulch, such as wood chips.
Blueberry plants are usually potted and are planted anytime, but are most available in winter and spring. If the plant is older and root-bound, the outer roots should be loosened or pulled away before planting. Plants should be set at the same height as the existing soil level, or slightly above if settling is expected.
In-row spacing for the various berries is as follows:
blueberry – 3 ft. (hedge) or 4 to 5 ft. (shrubs);
blackberry – 3½ to 4 ft.;
raspberry – 2½ to 3 ft. Rows should be 8 to 10 ft. apart.
— Information provided by the University of California Cooperative Extension