I have worked really hard over the past 8 years to convert our small, urban southern California yard into a productive mini-farm. I have Barbara Kingsolver and her book “Animal, Vegetable, Miracle” to thank for that. That book was transformational!
And thus began the conversion of our yard from boring landscaping to a productive mini-farm.
We now have six raised beds of various sizes for vegetables, a chicken coop and run with five hens, and a surprisingly diverse orchard.
Here are the fruit trees that are now growing in our yard, plus their winter chill hour requirements.But what are chill hours? Chill hours are the number of hours of cold (i.e. 45 degrees F or below) that are required to break down the growth-inhibiting hormones that cause a deciduous fruit tree to enter dormancy and stay dormant, so that normal growth can resume in the spring. A “low chill” variety is one with a 100-400 chill hours requirement.
Chill Requirements for the Fruit Trees
1 Apple, Fuji. 200-400 hrs
2 Apple, Gala. 200-500
1 Apple, Granny Smith. 400
1 Apricot, Katy. 200-300
1 Asian Pear, 20th Century. 300-400
1 Asian Pear, Sheinseki. 250-300
1 Asian Pear, 4 varieties grafted, 250-400
1 Avocado. 0
1 Blackberry. 100-500
2 Lemon, Eureka
1 Lemon, Meyer
2 Lime, Bearss
1 Orange, Navel
1 Orange, Valencia
2 Grape, Red Flame Seedless. 100+
1 Nectarine, Panamint. 250
1 Nectarine, Snow Queen 250-300
1 Peach, August Pride 100-200
1 Peach, Babcock Improved 250-300
1 Peach, Florida Prince 150
1 Peach, Garden Gold. 450-500
2 Persimmon, Fuyu 100-200
1 Plum, Santa Rosa 300-500
1 Pomegranate, 100-200
25 Total trees (not counting the grapes and blackberries, and not counting our olive tree, which we keep pruned so it doesn’t produce messy olives)
When selecting fruit trees, I paid attention to the number of chill hours that each variety required. We live in coastal Orange County, which is known for its moderate, pleasant climate: highs in the 70s, lows in the 50s, year round. But as you saw from the table above, most deciduous fruit trees need a certain amount of chilling in order to set fruit and remain healthy.
Microclimates affect chill hours. For example, in San Diego County, the average number of chill hours are:
- Coastal strip (within 10-15 miles of coast) = 50-250 chill hours
- Median areas (between 10 & 25 miles of coast – La Mesa, Clairemont, etc.) = 200-400 chill hours
- Inland areas (El Cajon, Spring Valley, Escondido, Jamul, etc.) = 400-600 chill hours (source: California Rare Fruit Growers, San Diego Chapter)
The folks at UC Davis Fruit and Nut Research Information keep track of chill hours for us, and track it thoughout the winter season (November through February). So far, we have had only 76 chill hours this 2014/2015 winter season, which isn’t enough for most of my deciduous fruit trees to set fruit. To check out their table, see
Global warming is definitely affecting the number of chill hours we receive. It is going to affect commercial growers as well. For example, chill hours in California’s Central Valley have declined by 22% over the past 60 years. Farmers and home orchardists may be wise to search out varieties with lower chill hours.
As acknowledgment of our changing climate, I chose to plant low chill Fuyu Persimmons and a pomegranate as the most recent additions to my orchard.
For more information on how to grow and care for fruit trees in southern California, I recommend this great PowerPoint from San Diego County.
I hope you enjoyed this overview of my mini-orchard of mostly dwarf and semi-dwarf fruit trees. They are still maturing, so I hope that their prime bearing years are still ahead of them.