It has been a stressful winter for landscapes across much of Colorado. Below average moisture, persistent winds and mild temperatures have left lawns, trees, plants and shrubs thirsty.
Colorado State University landscape experts suggest a little water now will go a long way later. "We definitely want to encourage homeowners to water their trees and woody plants," said Jim Klett, professor in the Department of Horticulture and Landscape Architecture at Colorado State.
The dry conditions present difficulties for plant roots, particularly those planted last season that were not watered during the winter. Even established plants in warm exposures may show signs of winter drought once hot weather arrives in June due to compromised root systems.
"There may have already been some damage done – there is evidence of twig dieback, or dried tips on some trees," said Klett.
Broadleaved and needled evergreen trees, especially those planted or transplanted last year, are subject to winter desiccation – or "winterburn". The lack of sufficient moisture results in leaf scorch in broadleaf evergreens such as Oregon grape holly and English ivy. Needled evergreens, especially certain junipers and arborvitae, may develop extensive needle browning. Pines show needles with a half green, half brown look.
Klett, who also serves as a landscape horticulturist for Colorado State Extension, said even perennials could be impacted by the dry winter. "The strong winds that have been blowing and rapid changes in temperatures which result in freezing and thawing of the soil can cause the roots of perennials to be exposed and result in winter damage and drying," said Klett.
Klett suggests ten gallons of water for every one inch diameter of tree with watering occurring every two-to-three weeks. Lesser amounts of water would be needed for shrubs and perennials. More information is available in the Colorado State Extension Fall and Winter Watering fact sheet – http://www.ext.colostate.edu/Pubs/garden/07211.html.
Lawns are being impacted by the lack of moisture according to Tony Koski, professor in the Department of Horticulture and Landscape Architecture and a turfgrass specialist for Colorado State Extension.
"The soil is so dry right now that it could prevent root production and now is the time of year that a lawn’s root system is developing," said Koski. "Poor root system development could mean that lawns are less drought resistant later in the summer."
Koski said other good reasons to water in moderation now include limiting pest problems. Mites favor dry turf for reproduction and Koski said the most effective control is water. He said homeowners are beginning to apply fertilizers and weed pre-emergent, which require water to be activated. Lawns that are to be aerated should also be watered for maximum effectiveness.
At this time of year, bluegrass and fescue lawns require about half an inch to one inch of water every two to three weeks to stimulate root production. Koski warns, however, that buffalograss lawns should not be watered until early May.