Cherry chill hours requirements vary significantly between the different cherry tree varieties.
Deciduous fruit trees require a rest period during winter. This phase is called chill accumulation requirements or needs. These requirements are the result of the climatic adaptation of the different fruit species to their environment. Breaking the sleep depends on the accumulation of chill hours. This is a way that fruit trees have to reference the beginning of spring and protect themselves from the sudden changes in temperature that usually happen during winter.
Until the necessary chill hours accumulate. The tree does not leave its sleeping state. In case of chill hours deficiencies, the cherry blossom becomes irregular.
Calculation and consequences of not completing chill hours
There are several ways to calculate chill hours, the most common is to count the hours below 7ºC.
A correct exit from rest is essential for deciduous fruit trees to produce.
The shortage of chill hours produces the following symptoms:
1.- The opening of wood and flower buds is delayed.
2.- The sprouting of the tree is irregular or staggered, sprouting some branches before others.
3.- The tree is detached from the flower buds, preventing the production of fruit.
Finally, the severity of the symptoms described above will depend on the difference between the chill requirements and the chill that the tree has received during the resting phase.
Cherry tree chill hours
The following data have been published by the breeders of the varieties or by data published by research centers (IMIDA). They are arranged according to the estimated chill hours needs for different cherry tree varieties.
Low chill cherry trees (Brooks, Early Bigi, Royal Tioga…). And popular cherry tree varieties Burlat, Van, Bing and Lapins cherry chill hours.
| Cherry variety | Chill hours 7ºC | Chill Units (Utah) | Flowering time |
| Cristobalina | 314 | 510 | Extra-Early |
| Royal Tioga | 500 | Extra-Early | |
| Royal Hazel | 500 | Early | |
| Brooks | 519 | 854 | Early |
| Early Bigi | 571 | 934 | Early |
| Lapins | 592 | 963 | Early |
| Satin | 600 | Early | |
| Burlat | 604 | 934 | Half |
| Ruby | 610 | 968 | Early |
| Bing | 623 | 993 | Half |
| Primulat | 629 | 972 | Early |
| Sweet Heart | 649 | 1019 | Half |
| New Star | 654 | 1028 | Early |
| Van | 668 | 1036 | Half |
| Santina | 671 | 1039 | Half |
| Utah Giant | 800 | Half | |
| Sylvia | 800 | Late | |
| Kordia | 900-1,000 | Late | |
| Summit | 1,100 | Late | |
| Regina | 1,000-1,200 | Late |
As we can see, the cherry tree varieties with less chill requirements are early flowering. In contrast, late flowering varieties have high chill hours requirements.
This is due to the relationship between the accumulation of chill hours and the departure from winter rest.
Importance of chill hours in cherry production
Precise planning of the chill hours to which our cherry plantation will be exposed is essential. In areas with little accumulation of chill hours during winter, the cherry crop may not be feasible.
Recommended reading
Did you find our article interesting about the cherry chill hours requirements? We recommend the following articles on our website:
Collection of pests and diseases of the cherry tree.
Types of rootstocks for cherry trees.
Warning
We have translated the information on our website from Spanish to English. Note that some words may have seen their meaning altered during their translation.
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