Chill-Hours and Peach Tree Blossoms

The fruit of a peach tree starts its life as a flower. If your peach tree does not produce blossoms, it won’t have fruit later on. The exact timing of peach blossoming depends on temperatures during the winter and the variety of peach. The onset of flowers on a peach tree is also the time for applying fertilizer and spraying for prevention of common peach tree diseases.


How Winter Temperatures Affect Peach Blossoms

In order to break dormancy and blossom, peach trees need a certain amount of cumulative hours where night time temperatures fall below 45ºF (7.2ºC) and daytime temperatures do not exceed 60ºF ((16º C) in the months from November through mid-February.

The number of hours a peach tree requires in this chilly temperature range depends on the variety. At the low end, low-chill peaches need under 500 chill-hours, and some need as little as 100 hours.

Low-chill peach varieties are suitable for growing in areas with warmer winters and include:

  • Tropic Snow
  • May Pride
  • Bonanza
  • Red Baron

High-chill hour peach varieties need up to 1000 hours in the critical temperature range, and these peach cultivars are the ones to plant if you live in an area with long, cold winters. A few popular high-chill varieties are:

  • Contender
  • Cresthaven
  • Elberta
  • Flavorcrest

If you buy peach trees at a local nursery, they will most likely be suited for the chill-hour requirements for your area. However, if you purchase your trees from a catalog or on the Internet, it is important to double check that you are buying trees with chill-hour requirements to match your local conditions.

To find out the chill-hours in your area, do an Internet search or contact your local County Agricultural Extension office.

Problems with Peach Tree Blossoms

Even if you plant a tree with chill-hours suitable for your location, an especially warm or cold winter can reduce flowering and fruiting.

A warm spell during winter can cause a peach tree to begin flowering too early. When cold weather resumes, the buds are then damaged and likely to fall from the tree or fail to develop.

Planting trees with chill-hour requirements slightly below the chill-hour average for your area is one way of warding off this possibility.

Fertilizing and Spraying Peach Trees at Bloom Time

The onset of flowers on a peach tree is a signal that it is time to fertilize the tree. Fertilizing annually is also important for the development of flowers and fruit. Fertilizing can be done any time from the onset of flower buds until the beginning of July.

The budding stage of peach flowers is also the time for spraying fixed copper or Bordeaux mix for controlling common peach tree diseases such as brown rot and shot-hole disease.