By Judy Kunz, Colorado Master Gardener

If predictions are accurate, we are likely to experience a strong El Niño effect this fall and winter. El Niño refers to the dominant current in the tropical Pacific Ocean that has a strong influence on the weather in the U.S. and around the world. During El Niño years, precipitation tends to be heavier in the southern tier states, including the mountains in southwestern Colorado. The northern states, which include northeastern Colorado and the Front Range metro area, can tend to have higher temperatures and below normal precipitation. Because El Niño was detected earlier than normal this year, forecasts are for a strong effect that may rival the major El Niño of 1997 and 1998, which caused meteorological havoc across much of the country.

What does that mean for us along the Front Range? While no one has a crystal ball, it looks probable that our trees, shrubs, perennials, bulbs and turf will be in need of supplemental water during dry periods when the ground is not frozen and there is no snow cover. Particularly vulnerable will be evergreens such as pine, spruce, juniper, fir, yew and arborvitae. Because they don’t drop their needles in the fall like deciduous trees, evergreens tend to lose moisture during warm, dry periods. Also vulnerable are turfgrass, perennials and bulbs.

While our plants can’t talk to us, they can give us clues when they are stressed. Conifers will tend to show drought stress through browning of their needle tips, while deciduous trees will demonstrate stress through wilting of their leaves or branch dieback. Perennials indicate insufficient moisture through wilting of foliage and dieback at the crown, while lawns will have yellow or brown patches in dry areas in the spring as the turf greens up.

To prevent winter desiccation, give plants a deep watering this fall, mulch around the base of evergreens, shrubs, perennials and over bulbs to minimize evaporation, and water monthly during snowless periods when the ground is not frozen. For deciduous trees, on warmer days, use a frogeye sprinkler under the canopy of the tree out around the drip line where vulnerable feeder roots are located close to the soil surface. Check soil moisture levels by inserting a large screwdriver into the soil.

Taking a little time and effort now to ensure that plants have sufficient water during warmer, drier weather will keep them thriving into the future. See this fact sheet for detailed information on fall and winter watering and this video.