Chill Hours for Fruit Trees

Home fruit production is a part of our gardening experience. I have had quite a number of phone calls and email over the years by homeowners interested in fig, blackberry, persimmon, pear, citrus and peach varieties appropriate for Brazoria County. One of the best ways to begin planning for winning varietals is to rely on observed and predictive data specific to our county.

We have all experienced subtropical climatic conditions in Brazoria County, fussing through hot and humid summers and welcoming mild to cool winter. This climate puts us in a kind of sweet spot that allows us to successfully grow a variety of citrus, and also limits the variety of stone fruit such as peaches and nectarines appropriate for our area. The majority of Brazoria County lies in zone 9a of the USDA Hardiness Zone map, average minimum temperature between 20 and 25-degrees; coastal areas such as Freeport lie in zone 9b of the map. While this map is useful as a predictive model, we still need recent annual recorded data to make realistic choices. The challenge we face with cultivation of stone and pome (apple) fruit is reaching cumulative recorded chill hours appropriate to the fruit variety.

Chill hours (CH) is defined as chilling requirement calculated from cumulative cool weather events (between 32 to 45-degrees) that initiate bloom for fruit-bearing trees. Annual chill hours for Brazoria County can range from 200 to 400 hours. A great resource to calculate CH is offered by Mississippi State University online: I find this information very useful, and determined that the first temps below 45-degrees recorded in fall of 2019 for Brazoria County was October 31 at 40-degrees. It didn’t take much more time to calculate that Angleton has received 218 CH to date. This kind of information, combined with local soil analysis and landscape preparation can help you choose the right fruit tree for the right place in your orchard for future fruit production. As an example, a few peach tree varieties you may wish to include are Tropic Snow rated at 200 CH, August Pride at 300 CH, or pushing the boundary with La Feliciana at 400 CH.

I encourage you to visit my website and search links related to our Urban Orchard program to find out more about fruit and citrus tree culture at: I have posted CH data for the past five years on this website to give you grounded truth for fruit tree choices. Tree cheers to you and I’ll see you in the orchard.

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