How to Acclimate Apple Trees

Acclimate (ac·cli·mate): "To become accustomed to a new climate or to new conditions. Also to harden off a plant."

Acclimating apple trees helps to minimize environmental stress when planting. Since our potted apple trees are grown in the controlled environment of our greenhouses, they may arrive to you already sporting tender new growth. This growth can be sensitive to things like direct sunlight and sudden changes in temperature, so acclimating these apple trees to their new environment will help provide a great start. We strongly recommend following this simple process prior to planting apple trees that are leafed out and not dormant.

NOTE: This is part 2 in a series of 11 articles. For a complete background on how to grow apple trees, we recommend starting from the beginning.

Things that may cause injury to tender new growth in transplants:

  • Temperatures (below 50ºF or above 90ºF)
  • Frost snaps
  • Strong/direct sunlight
  • Wind

These conditions are more likely to occur during early spring, but can be expected during different times of year in different areas. Here are a few steps we recommend you follow to acclimate (or harden off) your apple trees prior to planting outdoors:

1. Upon arrival, keep your apple trees in the pots they arrived in and place them in a sheltered, shady spot outdoors — like on a back porch. Leave them there for 3 to 4 hours and gradually increase the time spent outside by 1 to 2 hours per day. Bring them back indoors each night.

2. After 2 to 3 days of this acclimation process, begin transitioning the apple trees from their shaded spot to one that provides some morning sun. Return them to the shade in the afternoon. If this conflicts with your schedule, try moving the trees to an area that receives filtered sunlight instead, which is less intense than direct sun. Be sure still to bring them indoors again overnight.

  • Water regularly as needed to keep the roots from drying out. If the soil in the pots is dry to the touch, then you know it’s time water. You may occasionally mist the leaves with water, since the environment indoors is drier than outdoors.
  • Observe foliage daily. If signs of leaf injury appear prior to planting, move the trees back into filtered sunlight and start from the first step again. Proceed to the second step when conditions improve.
  • After 7 days, your apple trees should be able to handle the outdoor conditions, as long as temperatures are expected to stay between 50ºF and 90ºF. If daytime temperatures are expected to drop within the next day or so, continue to repeat the second step. Monitor your trees, and the weather, until conditions are more suitable for planting outdoors.

3. After 7 to 10 days, and if the weather conditions are right, your apple trees are ready for planting in their permanent location. For best results, try to plant on a cloudy day.

Please note: these are general recommendations. Your particular growing environment might require a slight variation on these guidelines, since some trees can take more time (or less time) than others to harden off. Factors like the current year’s weather, individual trees, and your location can affect the acclimation process.

NEXT: Choosing a Location for Apple Trees
Previous: Introduction