Chilling Time for Fruit Trees
Fruit plants, and nut trees as well, need a certain amount of time spend dormant in temperatures from about 32 to 40 degrees Fahrenheit (0 to 4.5 Celsius) in order to develop flowers and fruit in the spring, summer, and fall. Chill time is measured in hours, and some fruits don’t need much. For instance, strawberries require just 200 hours, and this is why they can grow in warmer climates. Some need a lot of hours, though, and will only grow in colder climates as a result. Cherry chill hours are up there with the higher numbers, so to get fruit you can’t grow these trees in warm zones unless you choose the right cultivar.
Chilling Requirements for Cherry Trees
Cherries are adapted to colder climates, so they won’t break out of dormancy until a sufficient amount of time with cold temperatures has passed. There is variation in chilling hours for different types of trees and also between cultivars of one type of fruit, like cherries. Cherry cold requirements are generally between 800 and 1,200 hours. Zones 4-7 are generally safe bets for getting adequate chill hours for cherry trees. Knowing how many chill hours for cherries is necessary will depend on the cultivar, but for most types, in order to get the maximum yield of flowers and fruits, at least 1,000 hours is important. Some cultivars of cherry that can get by on fewer chill hours, known as low-chill cherries, include ‘Stella,’ ‘Lapin,’ ‘Royal Rainier,’ and ‘Royal Hazel,’ which need 500 or fewer hours. The latter does require a separate cultivar for pollinating, though. There are also some varieties that will give you a decent fruit yield with just 300 chill hours. These include ‘Royal Lee’ and ‘Minnie Royal.’ Both require pollinators but, because they have similar chill requirements, they can be planted together for pollination.
