Strawberries are indigenous to temperature regions in both the northern and southern hemispheres. Wild strawberries have been eaten by people around the world since ancient times. The modern strawberry that is popular today, Fragaria ananassa, originated from crosses of two New World species of strawberries, Fragaria chiloensis and Fragaria virginiana. The transition from these native species to the modern varieties that we eat today was a long process. The English did most of the early breeding work to develop the ancestors of the varieties we presently grow.
There are three main types of modern strawberries: June-bearing, ever-bearing and day-neutral. The main differences between the different types of strawberries involve the time of year of fruit production and winter hardiness.
June-bearing strawberries produce one strawberry crop/year. Plants flower in spring and fruit is ready to be picked in late June and early July (about a three-week fruiting time). The runners that the plants send out in fall will produce fruit for the following summer, so it is important not to remove these runners. Common June-bearing strawberry cultivars include; ‘Kent’ (mid-season maturity, high yielding, produces abundant runners, slightly susceptible to powdery mildew), ‘AC Wendy’ (early, one of the top commercial producers), ‘Bounty’ (late season maturity, average yields of larger berries), ‘Honeoye’ (mid-season maturity, firm fruit, produces over a longer period) and ‘Cavendish’ (mid-season, originated from Nova Scotia, large, firm, dark red fruit with excellent flavour).
Ever-bearing and day-neutral strawberries are often confused as the same type of strawberry, but they are not the same. Ever-bearing strawberries have two distinct fruiting periods: late-June into mid-July and again in late August to mid-September, whereas day-neutral strawberries also start producing in late-June to early July but continue to produce throughout the summer and into the fall until freeze-up. Typically, ever-bearing strawberries have smaller fruit size than other types but have better winter hardiness than other strawberry types. Day-neutral strawberries are usually planted as annuals but can be overwintered with mulch in a mild winter. When planted in spring, ever-bearing strawberries will produce fruit in late summer or fall of that same year. Runners should be left on the ever-bearing fruit plants as they will provide more plants and fruit for the following year. ‘Ogallala’ and ‘Fort Laramie’ are two common cultivars of eve-rbearing strawberries. ‘Ogallala’ fruit can be bitter if produced during hot weather. ‘Fort Laramie’ fruit is large and bright red. With the wider availability of day-neutral strawberries, ever-bearing strawberry types are not very common.
One big advantage of growing day-neutral strawberries is that they will produce a good crop of fruit in the same year that they are planted. Additionally, they will also produce fruit on runners that have not rooted, although runners that develop early in the season should be removed. Day-neutral strawberry cultivars recommended for northern locations include: ‘Tristar’ (medium sized plants and fruit with good flavour, resistant to verticillium wilt, leaf scorch and leaf blight however, excessive heat creates small fruit), ‘Fern’ (medium to high yielding, firm fruit with good texture, one of the best day neutrals for hardiness), ‘Seascape’ (firm large fruit with good texture, most of the fruit are produced later in summer) and ‘Albion’ (not winter hardy in northern locations, long, narrow, firm fruit, produces fruit later in the season)
Plant new strawberry plants as early as possible in spring after the site is prepared. Strawberry plants can withstand a slight frost. Strawberry plants are often sold in bundles as bare root plants: these are plants that have no soil around their roots and have been stored in cool, moist conditions. Once you receive the bare-root plants, you should plant them in your garden within one or two days. Keep the bare root plants cool and moist until you are planting out: sun and drying wind will kill the tender rootlets. Carry the plants in a pail of water, if necessary, while transplanting. Plant strawberries so that the midpoint of the crown is level with the soil surface. If the crown is covered by soil, the plant will either rot or fail to send out runners. If the strawberry plant is planted too shallow, the crown and roots will dry out. Gently firm the soil around all strawberry plants for good soil-to-root contact.
In-row spacing for June-bearing strawberries should be 30 cm, whereas ever-bearing and day-neutral strawberries should be planted in double rows 15 cm apart. Runners from the June-bearing strawberries will fill in the row. Between-row spacing for all strawberry types should be 1.0-1.5m.
Water in strawberry transplants with 10-52-10 fertilizer. Mix according to label directions. Thoroughly water the entire strawberry plants immediately after transplanting. For best results, keep strawberry plants well-watered throughout the growing season, but especially for several weeks after transplanting.
Strawberries require healthy soil for good fruit production. For June-bearing and ever-bearing strawberry patches, add a minimum of 8-10cm of compost annually in spring and work into the soil. If you prefer to use fertilizers, apply 200mL per 10 m2 of 34-0-0 after the June crop has been harvested.
For day-neutral strawberries, fertilize plants in mid-June, mid-July and mid-August with a high nitrogen fertilizer like 34-0-0 at a rate of 50 mL per 10 m2. Water the crop thoroughly after applying any fertilizer to prevent leaf burn on the plants.
Always harvest strawberries when they are ripe, red on the plant. Immature strawberry fruit does not ripen after harvesting. Ideal storage for harvested strawberries is 0-2°C and 90-95% relative humidity.
This column is provided courtesy of the Saskatchewan Perennial Society.
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