Growing The Saskatoon - A Prairie Heritage
Article by Richard G. St-Pierre, Ph.D.
(This article is a revised version of the article that was originally published in 2001 in The Cider Press 14(2): pp 19-24.)
Part 2: The Basics of Saskatoon Culture
Propagation
In order to retain the characteristics of the parental stock, some form of clonal or vegetative propagation (rooting of shoot cuttings, or micropropagation for example) should be used. Shoot cuttings are best taken from the crown of the plant; if taken higher up, the capacity to root is diminished. The limitation to this method is that a large number of stock plants are required to produce significant numbers of new plants. Micropropagation requires relatively expensive and specialized equipment but a single shoot tip or bud may be used to produce a very large number of new plants. The primary advantage of seed propagation is that seeds are easily extracted from fruit and very few stock plants are required to produce large numbers of plants. The primary disadvantage to seedlings is the genetic variability within the crop, which may result in variable plant height, uneven yield and the need to cull undesirable plants many years after establishment. First generation (F1) seedlings more closely resemble the parent cultivar than second generation (F2) seedlings, which should not be planted. Regardless of method of propagation, it is very important to obtain healthy, vigorous, high quality plant material. The best quality plants are 20 to 60 cm tall, straight from rootstock to tip, free of damage, with branches intact, and having a well-developed root mass. The roots should be fibrous, and not dry. Plants having tightly-wound roots should not be purchased. Although it is best to obtain dormant plant material, most propagators supply non-dormant plants. Consequently, before transplanting newly-propagated plant material, transplants must be hardened-off so that they can better withstand the move from the sheltered greenhouse or nursery environment to harsher garden or field conditions, which may be warmer, colder, and/or drier. Hardening-off should be initiated 2 weeks prior to transplanting.
Cultivars
There is no single best saskatoon cultivar. It best to grow more then one cultivar since performance and fruit flavour may vary substantially with site, growing season, and cultivar. The more commonly grown saskatoon cultivars include Smoky, Thiessen or Martin, Northline, and Honeywood. The cultivar Smoky is known for heavy yields. The cultivar Thiessen is characterized by very large flavourful fruit. The cultivar Northline has a smaller stature, tends to sucker freely, but yields well. Honeywood is a good, all-round cultivar.
Soil Requirements & Site Preparation
The saskatoon will grow on a variety of soil types but prefers deep soil with good drainage and soil textures ranging from sandy-loam to clay-loam. Good growth has been observed at a wide range of soil pH. Planting sites must be free of perennial weeds. Pre-planting a green manure crop such as oats will add nitrogen and organic matter to the soil.
Plant Spacing & Row Spacing
In orchards, typical plant spacing is 1 meter; row spacing may range from 3.5 to 6 meters. Wider row spacings are important to increase airflow through an orchard so as to reduce the risk of disease initiation and development by reducing the time leaves remain wet following a rain.
Time of Planting
Recent research suggests that early-season planting dates result in increased transplant survival compared with planting dates later in the season. There is a greater risk of poor transplant survival if planting occurs after the end of June. Fall planting appears to have variable results. It's important to avoid transplanting just before or during a time of environmental stress, such as during hot, dry periods, or when there is a substantial risk of frost. Planting in the spring while the plants are still dormant will decrease the danger of plants drying out because the soil is cool and moist; slow evaporation of water from the soil, and slow growth will allow for good initial establishment. Early planting helps to increase root growth. Transplanting may be done when soil temperatures reach 5oC. The use of dormant plants allows for a full cycle of plant growth, and therefore maximal root and shoot growth, which is not the case if non-dormant plants are used.
Planting Method
Plants may be placed into furrows, trenches or holes in the soil using a variety of equipment. Planting holes must be large enough to easily accommodate the root mass. In clay soils, the use of an auger or similar implement can glaze the walls of a hole, thus inhibiting water drainage, root penetration, and the transfer of water. Trenches in heavy clay soil may be susceptible to poor water drainage. Plant roots should be disturbed as little as possible and should not be allowed to dry out. When transplanting, plants should be set a little deeper (5 to 7 cm) than they were in the propagation container (in colder regions, frost heaving will push shallow-set plants out of the ground; once the rooting medium becomes exposed, the plants will dry out very quickly). The soil can then be firmed around the roots to remove pockets of air. However, growers must be careful not to transplant too deeply. Research on deep-planted maple and oak seedlings has indicated a decrease in survival and stem diameter, and an increase in susceptibility to winter injury, compared to seedlings that were planted with the root collar at the soil surface. Deep-planting may also lead to girdling (strangulation) of the stem by roots. Following placement, the plants need to be watered well, and consistently, but not overwatered.
Mulching
Mulches can be applied immediately following transplanting. Black plastic (2 to 3 mil, UV resistant) or fabric mulches are preferred. Such mulches effectively control weeds, retain soil moisture, and warm the soil earlier in the growing season, thus enhancing growth. Organic mulches tend to keep the soil too cool in the spring, thus having a negative impact on growth, and are labour-intensive to manage. Black plastic or fabric mulches can be applied in conjunction with a trickle irrigation system and fertilization is then done via the irrigation system. The transplants are placed in the ground first, and then pulled through a cross- or X-shaped slit in the plastic or fabric immediately after the mulch is laid. Care must be taken to avoid injuring plants during this process.
More information on saskatoon production may be found in: Growing Saskatoons - A Manual For Orchardists.