Peach tree chilling requirements

CHILLING REQUIREMENTS OF SELECTED PEACH VARIETIES M.L. Parker, Extension Specialist D.J. Werner, Professor Peach trees are deciduous and drop their leaves in the Fall and go into a developmental state known as dormancy. As the winter progresses the trees go into another state known as rest, during which they cannot grow even if environmental conditions are favorable for tree growth. Exposure to chilling temperatures is necessary to overcome this period of rest, after which normal bud break and growth can begin once growing conditions are favorable. The minimal necessary duration of chilling length for any particular variety is known as the chilling requirement for that variety. Temperatures effective in satisfying the chilling requirement normally range from 32 F to 50 F, with the optimal temperature being approximately 45 F. North Carolina typically receives in excess of 1,000 chilling hours annually. Peach varieties vary greatly in the number of chilling hours required from less than 200 hours to over 1,000 hours. The lower the chilling requirement, the earlier the tree will begin growing once temperatures are warm enough. The dilemma that is faced in North Carolina is the large fluctuation in winter and spring temperatures. For low chilling requirement varieties, the chilling requirement is quickly met during winter. Once the chilling requirement is met any warm period during the remainder of the winter will cause peach trees to prematurely bloom, and the blossoms will be killed by the next freezing temperature. However, for high chilling requirement varieties, if the chilling requirement is not met, trees will bloom very erratically, produce deformed leaves and have little to no fruit set in the spring. The latter scenario of insufficient chilling rarely occurs in North Carolina. In North Carolina, only varieties with a chilling requirement of 750 hours or greater are recommended to minimize frost/freeze crop losses. Varieties with a chilling requirement less than 750 hours are grown in North Carolina; however they are grown with a high probability of frequent crop loss and are not recommended for large plantings. Table 1 lists many commercial peach varieties and their chilling requirement. Varietal inclusion in Table 1 is not an endorsement of such variety. Table 1. Chilling requirement of selected peach varieties. Values listed are the hours required at or below 45 F. Chilling Variety requirement --------------------------------------------------- Belle of Georgia 850 Bicentennial 750 Biscoe 900 Blake 750 Bounty 800 Brighton 750 Camden 750 Candor 950 Cardinal 950 Cary Mac 750 Caroline Belle 750 Clayton 950 Contender 1050 Coronet 700 Correll 850 Cresthaven 850 Cullinan 850 Denman 800 Derby 750 Dixigem 850 Dixiland 750 Dixired 950 Elberta 850 Ellerbe 850 Emery 900 Encore 900 Fairtime 750 Fay Elberta 750 Fayette 850 Finale 750 Fireprince 750 Flavorcrest 750 Garnet Beauty 850 Glohaven 850 Goldcrest 650 Goldprince 650 Halehaven 850 Hamlet 850 Harbelle 850 Harbinger 850 Harbrite 850 Harken 850 Harvester 750 Havis 850 Hiley 750 Idlewild 550 Jayhaven 850 Jefferson 850 Jerseyglo 850 Jerseyland 850 Jerseyqueen 850 J.H. Hale 850 Junegold 650 Juneprince 650 Kalhaven 950 Keystone 750 LaFeliciana 600 LaGold 700 LaJewel 850 LaPremier 900 LaWhite 650 Legend 950 Loring 750 Madison 850 Marigold 650 Majestic 850 Marsun 850 Marqueen 750 McNeely 900 Monroe 750 Mountain Gold 850 Nectar 1050 Newhaven 950 Norman 850 Ouachita Gold 750 Parade 900 Pekin 950 Ranger 900 Raritan Rose 1000 Redcap 750 Redglobe 850 Redhaven 950 Redskin 750 Regina 850 Reliance 1000 Richaven 950 Rio Oso Gem 850 Rubired 900 Ruston Red 850 Scarlet Pearl 750 Sentinel 850 Sentry 850 Shippers Late Red 850 Southland 750 Springbrite 650 Springcrest 650 Springold 850 Starlite 650 Summer Pearl 900 Sunbrite 750 Sunhigh 750 Sunland 750 Sunprince 750 Surecrop 1000 Sweethaven 850 Topaz 750 Troy 950 Tyler 950 Velvet 950 Washington 950 Winblo 800 Whynot 950 ________________________________________ Published by North Carolina Cooperative Extension Service