Issue: February 26
Is this "living Christmas tree" hardy here?
Q. I was delighted to receive a European cypress tree for Christmas. I want to plant it outside in the spring. It says it is hardy in zones 5 to 11. What is my zone? Would it do better in San Angelo, Texas? It will be planted where it is in a sprinkling system set for 15 minutes 3 times a day, 3 times a week. It is a healthy and lovely tree and I want it to grow.
Mrs. L. E.
A. According to the USDA hardiness zone map, in Roswell, you are on the boundary between hardiness zones 6 and 7. That means your expected winter minimum temperature could be as low as -5 degrees F. This year you may have been colder. Based on the information you provided, this tree should survive in Roswell (if the stated hardiness is based on the USDA hardiness zone designations). Another complication is that there are several plants called European cypress. Based on the information I could find regarding these, they should all grow in Roswell. They will also grow in San Angelo (as you asked). This tree may grow somewhat better in San Angelo. Gardeners in other regions of New Mexico should check the plant hardiness zone in which they live if they wish to grow this, or other plants, to assure that they will adapt to your area. Use this web site with your zip code to determine your hardiness zone:http://www.plantmaps.com/interactive-new-mexico-usda-plant-zone-hardiness-map.php). The watering schedule you mentioned (15 minutes, 3 times a day, 3 times a week) is probably too much. I have seen cypress diagnosed with cotton root rot disease (which may be present in your area). This quantity of water increases the chance of root diseases. For proper irrigation the duration of irrigation should moisten the soil to a depth of at least 2 feet and in a broad ring (5 feet wide for a mature tree) around the dripline of the tree. The quantity of water to moisten soil to this depth depends on the texture of the soil (sand, silt, or clay). You will need to probe the soil to learn how long an irrigation system must run to moisten to this depth. Once the tree is established in the landscape (after 1 to 2 years), it should be watered once every 2 weeks during the growing season and once a month during the dormant season if there is not adequate precipitation to moisten the soil to a depth of at least 2 feet. Always moisten the soil to the same depth regardless of season, but change frequency of irrigation as the seasons change and water use by the tree changes. It will soon be time to plant it outside. Since it has been indoors, it is not hardy enough to tolerate the cold weather outside without allowing it to adapt. Gradually adapt the tree to the colder outdoor temperatures and brighter light. By mid-March (in Roswell) it should be safe to plant it outside. Your goal is to harden (adapt) the plant while waiting until there will be no hard freezes. If a very cold period of weather develops after you plant it, cover it with straw or other material to protect it.
Send your gardening questions to:
Yard and Garden, ATTN: Dr. Curtis Smith
NMSU Cooperative Extension Service
9301 Indian School Road, NE, Suite 112
Albuquerque, NM 87112
Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. New Mexico State University is an equal opportunity/affirmative action employer and educator.