By: Dr. Adam Dale, Dept of Plant Agriculture, University of Guelph
Published January 2025
Canada is an ideal country for growing berry crops. It has land, large energy resources, and a climate which is suitable for growing them. Many of the berries which are grown commercially are also found in the wild. These vary from blackberries and highbush blueberries in southern Canada to raspberries and strawberries in the south and central regions. Even in the north, cloudberries and arctic raspberries grow wild.
In the fifty years that I’ve researched breeding and production of berry crops, I’ve seen many changes both as a result of research advances, farm innovations and in the market place. When I first started most berry crops had a one to two month market window, although everbearing raspberries and strawberries were starting to interest the growers.
As I look back at what has happened over the years, I see the future as an exciting one for strawberry and raspberry growers. Breeders have developed varieties that fruit year-round and new greenhouse and field technologies have enabled these varieties to fruit year-round in Canada.
The first dayneutral strawberries were released in the 1970’s by Royce Bringhurst at the University of California, and the strong primocane fruiting raspberries, by Elizabeth Keep at East Malling Research Station in England. Since then, dayneutral strawberries have become popular in field and greenhouse cultivation. Because of improved greenhouse technologies, there are over 250 acres of strawberries grown in greenhouses in Ontario. Raspberries have moved into greenhouses more slowly, probably because it takes longer for raspberry canes to produce fruit. More recently, John Clark at the University of Arkansas has developed primocane-fruiting blackberries, but the greenhouse production systems still need to be developed for these.
The basic production systems have been developed for strawberries, and there are both commercial greenhouse and warehouse systems. However, issues remain around temperature and daylength to maximize production. The strawberry crown needs to be about 18ᵒC to maximize fruit number and size. I’ve suggested running cold water down a copper pipe above the crowns to maintain that temperature, but it still needs to be tested. When it comes to additional light, the big issue will be the supply and cost of electricity, and whether this will make production in warehouses unprofitable.
With raspberries the production systems have not been solidified. A basic question is which will be more profitable, growing long-cane floricane varieties, and discarding them when they have fruited, or using primocane varieties which will repeatedly fruit. With primocane varieties, the question becomes, how do we manage the primocanes so we get continual fruit production, and then how do we maximize the light to the lower branches to produce more berries on the lower laterals. It is easy to string a row of lights 1-2ft off the ground to increase light to the lower laterals, but then the question of electricity supply and cost can become an issue.
Finally, for strawberries, there are two further discussion points. The first: strawberries are produced from runner plants and dayneutral varieties produce runners while they flower. So, the best solution to maximize yield would be to breed plants that do not produce runners. Then how do you propagate them? The answer is to produce F1 hybrid, seed-propagated varieties. The plants can be produced from seed over the winter, so do not need to be grown for two years in the field, and would have less disease pressure. There are already F1 hybrid varieties in Europe, and we have been working towards F1 hybrid varieties in Ontario. We have some interesting F1 hybrids, but they are not ready to be released.
The second discussion point is one that excites me: strawberry miniberries. We developed these to be the size of raspberries, and they decap when harvested. Initial tests show that they can be sold for at least the same price as raspberries, and have produced a lot of interest from consumers, but the systems are not yet in place. We are propagating plants of one selection for a large-scale trial which should be planted in 2026. Growers have shown interest, but we had not been able to put the marketing side together. However, in the fall of 2023 a guy in marketing contacted me about something else, and I sent him a photo of the miniberries. The phone didn’t stop ringing for two days, and now he has interest from fresh market and processing companies throughout Canada and the USA.
In conclusion, I see the potential for a significant growth in the production and marketing of Canadian grown berries year-round. From what I hear, the market is there. We just have to get the systems working effectively so we can compete against imports. Then it will be interesting to see whether miniberries can be developed as a new type of berry.