You’ll want to hit your garden with a good dose of hydration at the end of fall. That’s particularly important for newly planted trees, shrubs, and perennials, says Sandi Blake, co-owner of Montana’s Blake Nursery. “This will help hydrate thirsty roots if precipitation is meager during the winter months,” Blake says.
The goal is for the water to soak deep into the soil: Aim for three feet for trees, two feet for shrubs, and a foot deep for your perennial plants, says Jacqueline A. Soule, a gardening expert and author of 13 books, including Month-by-Month Garden Guide for Arizona, Nevada, and New Mexico. A soil probe—available online or at a gardening store—will help you know if the water has penetrated deeply enough. A slow overnight drip from the hose is a good way to ensure your garden gets the water it needs, Soule says.
This deep watering will provide plants and trees with the energy required to survive the winter months, she says. In particular, says Soule, pines and evergreens can have a hard time if they get dehydrated. Any tree that stays green during the wintertime—such as citrus trees in Phoenix or palm trees in Las Vegas—should also get a thorough watering, she says.
Once winter hits, you may still need to water—but less frequently than during summer and spring. When temperatures are above freezing, try watering trees monthly and add more frequent irrigation for the rest of the garden based on your plants’ needs.
Mulch with care.
Once your plants are watered, you can add mulch—it’s helpful for perennials, trees, rose bushes, and shrubs, according to Soule. “They’ll survive winter better with a layer of mulch on top,” she says. By adding mulch, you’ll help regulate soil temperature and moisture levels, as well as add organic matter to the soil, says Braun.
Just make sure to mulch properly: “Pull mulch away from the base of your plants so it isn’t touching the stem or trunk. When mulch gets wet and is in contact with the plant, it can promote rot and disease,” says Missy Gable, horticulturalist and statewide director of the UC Master Gardener Program.