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Acclimating New Plants & Trees

Properly acclimating new plants and trees helps avoid stress and provides them with the best start possible. Get your new transplants established smoothly.

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

Acclimating a plant or tree for plants and trees that may not be in a dormant state when you receive them. Some plants and trees, like our potted berry plants and Stark® EZ Start® potted trees, are grown in the controlled environment of our greenhouses. When these plants ship to you, they may arrive leafed-out and already growing. This tender growth can be sensitive to things like direct sunlight and sudden changes in temperature, so acclimating them to their new environment will help provide the best start possible.

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

  • low temperatures (below 50º F)
  • frost snaps
  • strong/direct sunlight

Depending on the characteristics of the variety you are planting, some species (like pawpaw trees) generally may not thrive in full sun. Prior to deciding on a plant or tree, check its sun requirements so that you can avoid damage that may be caused by planting in stressful conditions.

Characteristics, found on our product pages, include sun requirements:

Example of Plant Characteristics

How to Acclimate/Harden Off Plants and Trees

If your new plants or trees from Stark Bro’s arrive in a pot and already display tender leafy growth, then they were likely grown in our greenhouses. Here are a few steps we recommend you follow to acclimate these plants and trees (or harden them off) before planting outdoors:

1. Upon arrival, keep your plants and 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 3-4 hours and gradually increase the time spent outside by 1-2 hours per day. Bring the plants back indoors each night.

2. After 2-3 days of acclimating your plants and trees, begin transitioning them 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 plants and trees to an area that receives filtered sunlight instead, which is less intense than direct sun. Be sure that you still 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 those plants or trees back into filtered sunlight and start from step #1 again. Proceed to step #2 at a later date.
  • After 7 days, your new plants and trees should be able to handle the outdoor conditions, as long as temperatures are expected to stay above 50ºF. If daytime temperatures are expected to drop within the next day or so, continue to repeat step #2. Monitor your plants, and the weather, until conditions are more suitable for planting outdoors.

3. After 7-10 days, and if the weather conditions are right, your new plants and trees are ready to be planted outdoors in a 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 plants can take more time (or less time) than others to harden off. Factors like the current year’s weather, individual plants, and your location may affect the process.

When it’s time to plant…

Proceed as you normally would:

  • Dig the planting hole so that it’s wide/deep enough to accommodate the plant’s root system with room to grow.
  • Remove the plant from the temporary shipping pot and loosen the roots so that they can spread out.
  • Prepare any soil additives you intend to use to amend the planting site.
  • Gently tamp out any air pockets as you cover the plant’s roots with soil.
  • Water the plant well and apply a 2-3 inch layer of mulch to protect the root system and suppress weeds.

Now that you know about acclimating new plants and trees that may arrive leafed-out (not dormant) in the spring, you’ll help get your new transplants established as smoothly as possible. Happy planting!


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