Chill Hours for Fruit Trees Guide
Growers (especially those in areas with warm winters) will need to know about the chill hours for fruit trees in order to have the trees produce bud and produce fruit. In this guide, we will go over
Chill Hours Meaning
Chill hours refer to the number of hours that a plant, usually a fruit tree, is exposed to temperatures between 32°F and 45°F (0°C and 7°C) during its dormant period. When the tree goes into a period of rest/hibernation (dormant period) it starts to track the number of days it is cold. Then when its needed number of cold days are met, it can come out of rest to bud and produce. So this period of exposure to cold temperatures is necessary for the plant to break its dormancy and properly bud out and grow in the spring.
Why Are Chill Hours Important for Fruit Trees
Most areas in the USA receive more than enough chill hours and therefore growers don’t need to worry about this number. However if you are in areas such as Florida or southern Texas and California that don’t get many cold days in the winter, you will need to find fruit trees that have low chill hour requirements. Without enough chill hours, the trees may not fully break dormancy. As a result the trees will experience delayed growth and reduced fruit production. On the other hand, too many chill hours can cause trees to break dormancy too early and be more vulnerable to frost damage or other stresses. Therefore, you will first need to know the chill hours in your area and then select the varieties that have the same or fewer chill hours for your area. As a result of this, you will get many fruits during the season.
How do I Find the Chill Hours in My Area?
Finding the chill hours in your area is a great way to ensure that your fruit trees and other plants are receiving the necessary amount of cold weather to break dormancy and grow properly. In fact, there are a number of ways to find the number of chill hours for your area.
Map of Chill Hours
California Chill Hours
- If you are in California, you can find the chill hours by following this link
- California Chill Calculator from UC Davis
Chill Hours for Florida and Georgia
- You can find the chill hours for Florida and Georgia by following this link
- AgroClimate Southeast Chill Hour Map (Florida and Georgia)
Texas Chill Hours
Chill Hours for Fruit Trees for other Parts of the USA
- Lastly, you can find the chill hours for any other area in the United States by using this national chill hour map. In fact you can even zoom to find the chill hours for your area.
- If you find that that these different tools have different numbers that is fine! Simply, take the average of the ones you find.
- You can also find the chill hours by checking with your local agricultural extension office or university extension. If this would interest you then you can find the one near you with this link.
Choosing Fruit Trees for Your Area: Chill Hours for Fruit Trees
Now that you have the estimated number of chill hours for your area, all you need to do is select the fruit trees that have the same or fewer chill hours. However since researchers haven’t studied chill hours extensively, we wouldn’t recommend stressing over getting the numbers exactly right. So perhaps you can think of these numbers as ranges, low, medium, and high. For example, low chill chill varieties would be 500 hours and below. Medium would be 500-700 and high chill would be more than 700 hours. Since some years you may have more chill hours in your area and some less due to warmer winters, we recommend choosing varieties with less chill hours or a range of chill hours just in case. Therefore keep in mind that trees with a low number of chill hours can still grow in your area if you have higher chill hours.
Chill Hours for Apple Tree
- High Chill Apples: more than 700
- Red Delicious: 800-900
- Honeycrisp: 800-1000
- Medium Chill Apples: between 500-700
- Gala: 500
- Crispin: 500
- Golden Delicious: 600-700
- Gravenstein: 700
- Newton: 700
- Rome Beauty: 700
- Braeburn: 700
- 3. Low Chill Apples: less than 500 hours
- Dorset Golden: 100
- Ein Shemer: 300-400
- Anna: 300-400
- Beverly Hills: 300
- Granny Smith: 400
- Fuji: 400
- Pink Lady: 200-400
- Gordon: 300-500
Peach Tree Chill Hours
- High Chill Peaches: more than 700
- Red Globe: 850
- Red Haven: 800
- Elberta: 800-900
- Hale Haven: 800
- Reliance: 1000
- Sentry: 850
- Loring: 750
- Majestic: 850
- Contender: 1050
- Encore: 900
- Medium Chill Peaches
- Goldcrest: 650
- Goldprince: 650
- Low Chill Peaches: less than 500 hours
- Bonanza: 200-250
- May Pride: 200-250
- Red Baron: 200-250
- Tropic Snow: 200-250
- August Pride: 300
- Donut: 200-300
- Eva’s Pride: 100-200
- Red Baron: 200-300
- Tropic Snow: 200
Chill Hours for Apricot Tree
- Medium Chill Apricots
- Tomcot: 500-600
- Royal Rosa: 500
- Moorpark: 600-700
- Harcot: 700
- Low Chill Apricots: less than 500 hours
- Katy: 200-300
- Gold Kist: 300
- Early Golden: 450
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