Berries Production Guide

Blueberries
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New Plantings Site Selection

This section was updated - 24 April 2021

With good soil and climatic conditions, and proper management, blueberries can remain productive for many years. There are productive south-coastal plantings that are over 50 years old. Consider the following when selecting and preparing sites for blueberries.

Soil

A soil test should be used to determine the nutrient status and soil pH before setting out a new planting. Have the soil tested at least 6 months before planting so that any amendments can be added as the field is prepared. Take soil samples from the top 30 cm (0 to 12 in). Consult a soil laboratory (for laboratory listings, refer to the BCAGRI publication, "Resources for Berry Growers") or contact the BCAGRI for a factsheet on soil sampling.

In south-coastal BC, blueberries have traditionally been grown on highly organic soils with an organic matter content of 20 to 50% (muck soils). However, they can also be grown successfully on mineral soils such as silt or sandy loam. Blueberries do not perform well in wet soils or heavy, poorly-structured clay soils.

Blueberries do best in acid soil with a pH range of 4.5 to 5.2. A pH outside this range can result in poor growth and low yields. See "Site Preparation" below to amend pH.

Drainage

Blueberries are relatively shallow-rooted and have fine, thread-like roots which require an open, porous soil. They require soils that drain well throughout the year and hold adequate moisture for good plant growth during the summer months.

Plants cannot tolerate extended periods of flooding especially when they are actively growing. Poorly drained soil can result in poor plant growth, poor yield, root rot and plant death. A water table maintained at least 60 cm (24 in) below the soil surface is best for blueberry production.

Irrigation and Water Quality

Most of the blueberry roots that take up nutrients and water are in the upper 40 cm (16 in) of soil and within the dripline of the bush. A uniform and adequate supply of moisture is essential for good growth and yields of quality fruit. In the south coast region of BC, rainfall is generally inadequate in July and August and supplemental irrigation is necessary. To determine actual crop water requirements and irrigation schedules, such factors as temperature, humidity, soil type, crop age and health, stage of crop development and presence or absence of mulch must be considered. Moisture demand is particularly great during fruit development - mature crops may require 2.5 to 4 cm or more of water per week. Moisture detection devices such as tensiometers or gypsum blocks can be used to help determine irrigation requirement. Local research is underway which will provide better information to develop accurate irrigation scheduling.

In the past, most blueberry crops in BC were irrigated with sprinklers, but presently most young fields are established with drip or trickle irrigation. Drip irrigation is more efficient as water is delivered directly to the root zone providing more consistent and even soil moisture. Fertilizers can also be injected into the irrigation water. The system must be designed with an emitter output and spacing to provide uniform moisture distribution. Because drip is so convenient, there is a tendency for some growers to apply more water than the crop needs which may lead to fruit quality problems and encourage the development of root rot.

It is very important to check the quality of available irrigation water before planting or installing an irrigation system. Water should have a low salt content (less than 700 TDS or an EC less than 1.2) and a low pH (less than 6.0). Ditch water may contain high levels of fecal coliforms which could contaminate fruit if overhead irrigated before harvest. Water high in iron may stain fruit causing it to be downgraded and unsuitable for fresh market sales. Refer to the sections "Water Management" for more information.

Contact a laboratory for the best way to collect water samples for testing (for laboratory listings, refer to BCAGRI publication, "Resources for Berry Growers"). Contaminants in the water may be removed with filters to enable overhead irrigation. However, filters which remove iron, can be costly. Ultraviolet (UV) treatment systems can be used to eliminate fecal coliforms. If poor quality water must be used, use an irrigation system that will not put water in contact with fruit. In some fields, controlled drainage or sub-irrigation can partially or fully substitute for an irrigation system. Micro jet or drip systems apply water to the base of the plants, thus avoiding contact with the fruit. Micro jet systems have larger orifices than drip systems and provide better water distribution and are less likely to plug.

Site Preparation

This is a critical step to successful planting. Start to prepare the field for planting the year before. Consider the following:

Wireworm Control

Check for wireworms in sites previously planted in grass. Plan for control. See "Wireworms" in "General Berry Pests".

 

Nematode Control

High nematode populations can contribute to poor growth and establishment of young plantings, particularly on sandy soils. Some nematode species (dagger) can transmit viruses such as tomato ringspot.

Submit a soil sample to a laboratory for a nematode test. If fumigation is required it is best done in early fall. (See "Nematodes").

Weed Control

Control established perennial weeds such as quackgrass, buttercup, horsetail and Canada thistle before planting.

Drainage

Install a drainage system before planting, especially in areas with poorly drained soils. Sub-surface drainage pipes are installed 0.8 to 1.2 m (2.5 to 4 ft) below the soil surface. If irrigation water quality is poor, the site conditions may allow for the drainage system to be used for controlled drainage or sub-irrigation. Refer to the "BC Agricultural Drainage Manual" for more information. Drainage systems work only as well as they are designed, installed and maintained.

Use management practices that promote good drainage. Raised beds help to overcome problems with high water tables but are not a substitute for a drainage system. Other ways to promote good drainage include: incorporating a small amount of sawdust in the beds before planting, covering raised beds with sawdust mulch, cover cropping between the rows, and periodically subsoiling in the wheel tracks of harvesters or tractors.

Field Layout

Fields should be designed for mechanical harvesting to allow flexibility in future harvesting decisions. Mechanical harvesting requires a minimum of 3 m (10 ft) between the rows. Provide a 4.5 to 5.0 m (15 to 16 ft) wide row break every 125 m (400 ft) for unloading harvesters and other machinery. Most harvesters require 7.6 to 9.0 m (25 to 30 ft) at the ends of rows (headlands) to turn around.

The risers or posts for overhead irrigation should be no higher than 2.1 m (7 ft) and placed in the centre of the row.

Plant on raised beds to reduce fruit drop when harvesting mechanically. Beds place the catcher plates nearer to the narrow base of the plant, keeping them in close contact resulting in less fruit drop. Build the beds 20 cm (8 in) high and 120 cm (4 ft) wide at the base. Raised beds are beneficial for plant growth regardless of harvesting method, especially in fields that are slower to drain. Bushes planted on raised beds, however, will dry out more quickly in the summer and require more frequent irrigation.

Soil Amendments

pH. Check and adjust soil pH before planting and every 3 to 4 years after planting. The optimum pH for blueberries is 4.5 to 5.2. Soil pH below 4.0 can be raised by adding dolomite or ground limestone at 2 to 4 tonne/ha (1 to 2 t/acre). Soil pH above 5.5 can be lowered with elemental sulphur. To lower the pH of a loam soil from 6.0 to 5.0 incorporate about 1.75 tonne/ha (1500 lb/acre) of elemental sulfur (flour or prilled sulfur) into the soil several months before planting. If pH is over 6.0 higher rates of sulfur and more time will be required. Sawdust, incorporated into the soil when beds are formed, lowers the soil pH slightly, and also increases the organic matter content.

Phosphorus (P) and potassium (K) do not move readily in the soil. In new plantings, broadcast and incorporate required P and K (as determined by a soil test) in the bed before planting.

Manure and compost. Manure and compost are valuable sources of crop nutrients and organic matter. They contain nitrogen, phosphorus, potassium, calcium and several micro-nutrients which are required by blueberries. Manure can be used prior to planting as a partial source of nitrogen, but timing application and balancing with other sources of nutrients is essential. Compost should only be used as a partial source of nitrogen in the planting year. High rates of compost or manure may contribute to an undesirable rise in soil pH. Refer to section on "Manure Use" in Nutrition Management.

Sawdust. On heavy, clay soils or very sandy soils, plants may benefit from the incorporation of sawdust into the beds before planting. However, research in Oregon has shown that for friable, loam soils, there is no short-term benefit from the practice and that growth may even be restricted. Before transplanting on heavy or sandy soils, apply a 5 to 10 cm (2 to 4 in) layer of sawdust over the planting bed and incorporate into the top 15 to 20 cm (6 to 8 in). Build raised beds after the sawdust is incorporated.

Any woodwaste containing high levels of bark, especially hog fuel, should be checked for salts.

Planting

Plant Source

Several serious diseases such as blueberry scorch virus can be introduced to the field on planting stock. Purchase plants only from reputable nurseries where propagation is done according to an accepted protocol which includes isolation, aphid management and testing for scorch, shock and other viruses.

Spacing

Between rows. See "Field Layout".


Between plants. The most commonly used in-row spacing is 90 cm. Research in Oregon has shown that varieties such as Duke and Bluecrop can be planted as close as 45 cm and will benefit with higher yields in the early life of the planting. However, more pruning labour may be necessary when the field is mature.

Table 1. Plant requirements at different spacings
Distance between plants in metres Distance between rows in metres Number of plants required
Hectare Acre
0.6 2.7 6173 2469
0.9 2.7 4115 1646
1.2 2.7 3086 1235
0.6 3 5556 2222
0.9 3 3704 1481
1.2 3 2778 1111
0.6 3.3 5051 2020
0.9 3.3 3367 1347
1.2 3.3 2525 1010

Planting

Planting can be done in the fall or spring. However, in colder areas, spring planting is preferred to avoid losses due to frost heaving. In coastal areas, fall planting may allow quicker plant establishment.

Generally, two year old nursery-grown plants are used to establish a planting. Ensure that root balls are thoroughly wetted prior to planting. When planting container-grown plants, inspect the roots and if pot-bound break apart the root ball before planting. This stimulates root growth and breaks the circling pattern of root growth that often develops. This is especially important if plants have been grown in pots longer than three years.

Set plants at the depth they were planted in the pot or nursery. If planted too deep, roots and crown may be deprived of oxygen resulting in plant death especially in heavier soils. Fill in the soil and press firmly around the plant to maximize soil-root contact.

After planting remove the low, weak twiggy growth at the base of the plant, leaving the strong healthy canes. Irrigate after planting if required.

Strip off flower buds in the establishment year and in the second growing season to encourage plants to develop strong roots and a good framework of canes for future fruit production.

Fertilizing

No fertilizer should be put in the planting holes. Plants set out in the fall should not receive any fertilizer until the following spring. Fertilize plants set out in the spring 3 to 4 weeks after planting. Two or more applications may be required through the first growing season. With young plants it is best to apply only small amounts at a time. If sawdust mulch is used, more fertilizer will be required to make up for the nitrogen taken up by the decomposing sawdust. Use caution when fertilizing young plants. Keep fertilizer about 10 cm (4 in) from the base of the plant. Spread fertilizer thinly and evenly to slightly beyond the dripline. Do not fertilize when the soil is dry. Refer to "Nutrition" in "Established Plantings" for further details and rates.


Cover Crops

Cover crops in blueberries are usually permanent grass covers between the rows. They suppress weeds, provide support for farm machinery, improve soil structure and water infiltration and reduce soil erosion. Grasses that work best are low-growing perennials that are easy to establish and do not creep. Mixtures should contain no more than 25% perennial ryegrass to minimize mowing. Pure stands of sheep fescue or hard fescue establish slowly but withstand traffic well and require less mowing.

Seed in spring or early fall (September). Seed mixtures at 30 to 55 kg/ha (12 to 22 kg/acre) and fescues at 30 to 45 kg/ha (12 to 18 kg/acre). Irrigate to establish grass covers or time seeding with rainy periods. Mow cover crops regularly during the growing season to control annual weeds. Unmowed cover crops can attract field mice. Control cover crops that creep into the row by applying herbicides in a band along the edge of the cover crop beside the sawdust mulch. Do not allow dandelions or other early flowering weeds to grow in between rows. When they bloom they can attract bees away from blueberry flowers.

Sawdust Mulches

Mulching keeps the soil cool, aids in water conservation, increases organic matter in the soil, improves soil structure and helps control annual weeds. Blueberries often grow more vigorously and produce better yields if they are mulched. Apply 5 to 8 cm (2 to 3 in) of sawdust to the surface of the bed the first year and every 2 to 3 years to maintain the mulch. The roots tend to grow into the mulch so as it decomposes the plant roots may become exposed if the sawdust layer is not maintained.

Microbial activity, which decomposes the sawdust, takes nitrogen from the soil. Nitrogen application rates may need to be increased by 30kg/ha (12 kg/acre) in the first few years if sawdust is used.

Several types of sawdust, including fir, hemlock and alder, have been successfully used on blueberries. Traditionally, cedar sawdust has been avoided because of concerns that its oil leachate may injure the crop. In recent years, because of a shortage of other types, some growers have applied cedar sawdust with no apparent negative affects.

Any woodwaste containing high levels of bark, especially hog fuel, should be checked for salts.

The use of sawdust is an acceptable practice under the "Code of Agricultural Practice for Waste Management." However, woodwaste or woodwaste leachate should not be allowed to escape to the environment. Limit the use of woodwaste on roads and near ditches. For any use of woodwaste greater than 50 m3, BC Ministry of Environment requests that a "Woodwaste Discharge Information Sheet" be provided to the Regional Manager.

Trellising for Mechanical Harvesting

Many varieties are successfully picked by over-the-row self-propelled harvesters (see recommended varieties). Most varieties require a trellis system to hold the branches in an upright position during harvesting. Trellising will also allow for better equipment access for late season sprays for spotted wing Drosophila. This system can be put in place the year before machine harvesting begins. Wood posts used for trellising should be treated to extend their life. Posts should be 64 to 76 cm (25 to 30 in) in height and spaced 5.5 to 7 m (18 to 23 ft) apart. Use high tensile, 12 gauge, triple galvanized wire. Use wire or wood cross members to prevent the wires from spreading under heavy fruit loads. Spacing between wires and the distance from the ground will differ between varieties. Wires for Bluecrop are commonly spaced 45 to 50 cm (18 to 20 in) apart and 0.6 m (25 in) high.

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