March 25, 2017

1- Trees grown in containers can be done almost any season in New Mexico, but if the trees have been in the container too long there may be problems.

Yard and Garden March 25, 2017


I have a pinon tree that has been in a pot for several years. I would like to plant it in the ground. Is it too late to do that this year?

- Mary P.

Via NMSU University-Wide Extension


The answer to your question is that it is not too late to plant your tree in the ground. Container grown trees and shrubs can be planted in the ground almost any time. If the ground is frozen in higher elevation and northern parts of New Mexico, it is better to wait until the ground has thawed. In the heat of summer most trees and shrubs can be planted if they are protected from drying winds and if they are watered properly. In fact, mid-summer can be a good time to plant if the monsoon provides clouds and moisture to help the tree avoid desiccation. The spring can create challenges with wind, so gardeners who plant trees in the spring time must protect their plants from the wind. If that means staking, be sure to stake the plants in a manner that protects them against girdling by staking materials. I like wide bands of softer fabric (cotton tee-shirt or old stockings) at the point of contact with the plant. Do not tie this or any other material tightly around the trunk when staking, but allow room for the trunk to grow and allow for some movement of the trunk. Remove or loosen any staking material at the end of the growing season.

Your question does raise a different concern. Your question referenced a piƱon pine tree that has been in a pot for several years. This could be cause for some concern. How large is the pot the tree is in? How many years has it been in the pot? When a tree or shrub grows in a container, its roots cannot spread out as they would in the open soil. The roots grow to the side of the container and begin to grow in a circle. When we transplant container grown trees and shrubs into the garden, it is often necessary to cut the circling roots. If the roots are cleanly cut, not torn, they will often form new roots at the point where the old root was cut. The goal is to have new roots that grow outward, not in a circle. This allows the tree to reach out for more water and nutrients as the roots extend outward. In the case of plants that have been in a container for many years, the roots may have lost the capacity to regenerate new roots, so the option is to cut the roots and risk having the tree die fairly rapidly, or leave the roots uncut and watch the tree die a lingering death. Trees with circling roots rarely prosper. It is more likely that a conifer, such as your pine, will be unable to form new roots than a deciduous tree. If the tree has been in the pot for many years, you may find that you will have greater success starting with a new tree from the nursery. However, if this plant has special meaning and must be planted in the landscape, be aware that it may grow well, or there may be problems.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


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