Issue: April 23
Late April to early May is a safe time to move houseplants outside in most of New Mexico, but carefully adapt them to the outdoor environment.
Q. Is it safe to put houseplants outside now? After I moved my plants outside last year most of the leaves died.
M.J.
Albuquerque area
A. Thank you for telling me where you live. In the Albuquerque area, it is safe, or will soon be safe to put houseplants outside for the summer. If you are in the valley or high elevation areas, you may need to wait until the first week of May. Gardeners in Southern New Mexico are certainly safe to move plants outside (except those at high elevation). In Northern New Mexico, gardeners should wait a few more weeks.
In any event, you should watch the weather reports and be prepared to move plants back indoors or cover the plants. Frost and freezes are unlikely, but not unheard of this late in the Middle Rio Grande areas.
The reason for the loss of leaves last year can be due to several causes. Leaves formed under low light conditions indoors will not adapt well to bright light or full sunlight conditions outside. The plant will form new leaves adapted to the new light levels. You can minimize the impact of changing light conditions on the plants by first moving them outside to a relatively shady location, and then gradually move them to brighter locations until they are in the place you will keep them for the summer. This gives the plant time to adapt by forming new leaves and, in some plants, to increase the light tolerance of existing leaves. At least the plants should not totally defoliate.
Dry winds can also cause leaf loss. Plants that have been protected all winter may not tolerate our outdoor winds well. Move them first to a location sheltered from the wind. Even in mid-summer, winds can cause leaf damage. The plants may also have experienced more rapid drying of soil when placed outside. Plants growing outside may lose water from the soil through the soil surface, the walls of clay pots, and their leaves more rapidly than when they were inside. You may need to alter your watering frequency when you take the plants outside.
A period of cold weather can also cause loss of existing leaves. Some tropical plants can be injured by temperatures well above freezing. Such plants should be kept indoors until night temperatures are consistently above 50 degrees, or should first be placed in a sheltered location where the night temperatures will remain above 50 degrees.
When you move your plants outside you should give the plants protection to allow them to adapt to new growing conditions (just as you do when you bring them indoors in the autumn), and you should alter your cultivation practices to accommodate the new environment in which you grow your plants.
For more gardening information, visit the NMSU Extension publications World Wide Web site at http://aces.nmsu.edu/pubs/_h.
Send your gardening questions to:
Yard and Garden, Attn: Dr. Curtis Smith
NMSU Agricultural Science Center
1036 Miller Rd. SW
Los Lunas, NM 87031
Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. NMSU and the U.S. Department of Agriculture cooperating.