Knowing when to prune your roses and other shrubs takes some knowledge of the plant type, cues from nature and a little guesswork. In the low desert, hard pruning usually begins in winter (January or early February) to stimulate early spring growth. A second prune in summer can lead to additional blooming. See Noelle Johnson’s post for more tips on rose pruning in the desert garden.
In cooler areas of the desert or in Southwest mountain communities, we need to prune a little later. Some shrubs can take a late winter pruning, especially if new growth already begins appearing in February or March. But roses and other woody shrubs need a little more time.
Clues to Pruning Times
I learned a few years back that it is best to wait and prune my roses when forsythia blooms begin to open. I’ve got a few forsythia shrubs, so it’s a wonderful gauge, and encourages me to be patient with my native and hybrid roses. The forsythia shrubs typically bloom by late March or early April here in zone 6B.
In middle deserts, late February to early March also are good times for rose pruning. Albuquerque (zone 7) master gardeners recommend rose pruning in late March. I’ve found, however, that the forsythia blooms a little earlier than sources suggest and that many Albuquerque gardeners begin pruning by early March.
You can’t predict the weather, but you can avoid pruning roses or other shrubs when temperatures are close to freezing. It is typical in some Southwest regions to get another frost after pruning, and that is OK. but you shouldn’t cut the fleshy stems of roses and most shrubs on really cold days with danger of frost in the next day or so. The cuts need some time to heal before hit with bitter cold.
You can’t wait until the last frost to prune most garden plants in high deserts and mountains. Those frosts can come well into mid-or late spring. The best clue is when you see some consistent green growth at the base of the plant or on its branches, and before flower buds form. In any Southwest region, check with a local source or trusted regional gardening book or blog to get a better idea of when to prune specific shrubs, especially if this is the first year you prune them.
When the Shrub Blooms
The only other trick to timing of pruning is to avoid late winter/spring pruning of shrubs that bloom in spring. Many of these, like lilacs and the forsythias, develop flowers on old wood from the previous fall. If you prune the shrub too late in winter or spring, you actually remove the flowers and might get few to no blooms this season.
Sometimes, your shrub requires a rejuvenation prune, as I did with my forsythias last year. If the shrub needs it for health or has just grown out of control, go ahead and prune when it is dormant in late winter or early spring. Just don’t expect much in the way of flowering the first spring after pruning, and maybe the next year. But know you have improved the shrub’s long-term health. Most other native and waterwise shrubs bloom in summer, which means you can prune in spring when they begin to show signs of new growth.
Most modern bush roses develop blooms on new wood, so they are best pruned in late winter to early spring. Most climbing roses bloom on old and new wood, so they flower best if pruned in mid- to late winter while dormant. Some climbers or ramblers continue blooming or bloom on old wood from the prior year, so it is best to prune them after they have finished flowering in fall. You can prune them through winter, but if you wait until spring, you might remove old growth. If you aren’t sure, try researching the type of rose or watch its blooming behavior the first summer for clues.
Most shrub roses and other large shrubs also can endure removal of dead canes or branches in fall, while the plant still has leaves. This helps you better spot and reach those unsightly bare branches. Some landscape roses such as the Knock-Out roses benefit from a light fall trim that lowers their height about one-third and secures them better for late fall and winter winds. You can then fine-tune and trim a little more in spring.
The best hints, then, are to watch the plant, oncoming weather and other savvy gardeners in your neighborhood for help. Or check with local master gardeners and other trusted resources. If deer can’t kill most roses and shrubs, you probably can’t either. Do your best and enjoy!
Teresa Odle is the editor of African Violet Magazine, a freelance editor for BobVila.com, and author of a blog on low-water gardening in the Southwest. Teresa trained as a Master Gardener in Albuquerque, N.M. She grew up in the Phoenix area, and has lived in the mountains of northern New Mexico. Teresa and her husband now attempt to manage four acres of land in zone 6B of southeastern New Mexico. The land includes a large xeric garden, herbs and vegetables, and a small orchard that borders the Rio Ruidoso in Lincoln County. Teresa’s blog, Gardening in a Drought, won a 2016 national award for best writing in digital media from the Association for Garden Communicators.