Roses are America’s national floral emblem, designated so by Congress in 1986. Their assets as flowering and fragrant blooming shrubs are winners in any garden style. They’re happiest with plenty of sun and well-drained, amended soil. Most Colorado yards give them the first; it’s up to you to give them the second. Here’s a quick primer on caring for existing roses and installing new ones.
ROSE PRUNING
• Late April into May is the ideal time to prune back roses. If they’re pruned too early in spring, the tender new foliage may be frost nipped — and that sends your rosebush back to square one for the season. In higher elevations, you should wait a few more weeks.
• That said, do prune. It increases flower production and improves the size, shape and health of your rose. How much to take off? That varies based on the amount of dieback and rose type. Many roses took a beating from the November flash-freeze event — and some didn’t make it. Check for tender new growth at the base of the plant before you give up, dig it out and shop for a replacement.
• Modern shrub and old garden roses need the least pruning. Climbers and once-bloomers prefer being pruned after their first flowering. Hybrid tea, grandiflora and floribunda roses often need a heavy prune, in many cases all the way to the ground. (This means if you have more than three roses, file those plant tags.)
• Wear gloves and use sharp bypass pruners, loppers or a pruning saw.
• Follow the three Ds: Prune dead, damaged or diseased wood back to healthy tissue which has the green bark on the outside of the cane and white pith on the inside. Also prune out thin, weak canes, and cut old woody canes close to the ground. The goal is to open up the plant so sunlight and air can get inside.
• Cut on a 45-degree angle, close to an inch above an outward-facing bud eye (the swollen part on the cane where the leaf attaches). Check out a video on how to prune roses at denverpost.com/DPTV.
• Fertilize roses soon after pruning, following package directions.
• Use a complete fertilizer (one that containers nitrogen, phosphorus and potassium). Water before applying the fertilizer, then water again.
• For a face-to-face demo, attend a free Denver Rose Society pruning workshop, 9:30 to 12:30 a.m., April 25 at the Jefferson County Detention Center. More: denverrosesociety.org /calendar.htm
BUYING ROSES
• Roses are sold three different ways. Garden centers carry them potted in containers, usually 2- or 5-gallon in size. Bare-root roses are mostly available online; packaged roses are generally sold in big-box stores. Both bare-root and packaged roses become available in early spring, and cost less than container-planted roses. But it’s best to purchase, and then plant, these two types as soon as they are available in late winter or early spring.
• How deep should you plant a rose? It depends on whether it is grown on its own root, or grafted to the rootstock of a different, more vigorous variety. Roses are grafted either because the top variety is less cold-hardy, or to get a more robust rosebush, which wouldn’t be possible without a stronger root stock. It’s easy to see the difference between own-root and grafted roses if you look closely. A grafted rose has a small knot or fist-like knob, called the bud union, above the roots or soil line in a container. An own-root rose has no grafted knot.
• Planting grafted roses correctly is very important to their success. The graft must be 1 to 3 inches below the soil line. More on planting bare-root and container roses: www.ext.colostate.edu/pubs/garden/07404.html
• Many wholesale growers use rootstock from a rose named Dr. Huey. If the graft is not planted deeply enough, or planted with the graft exposed, the top rose — the grafted one — may die. But those Dr. Huey roots are survivors and may grow at will once the graft dies. So if your repeat-blooming yellow grafted rose has morphed into a prolific, deep red, semi-double, once-blooming rose, you’ve likely met the good doctor. My advice: Dig him out thoroughly and re-plant — with an own-root rose or one correctly planted with the graft below ground.
• Shop garden centers now for the best selection of roses, but refrain from planting until well after the average last frost date in your location — mid-May for many Denver metro areas. If your rose was grown in a greenhouse, it’ll need hardening off before planting.
ROSE SELECTION
• Choosing roses is fun. What type do you want? Consider your landscape first, but after that, grow what you like.
• Do research online, in books or at a local nursery. “Growing Roses in Colorado,” a 55-page book produced by the Denver Rose Society, is available at indie garden centers and botanic gardens’ gift stores. is at helpmefind.com
/rose/index.php.
• Look for All-American Rose Select winners; you’ll see AARS on the plant tag. This means the rose was evaluated by the rose industry.
ROSE TYPES
• Climbers will need a trellis or wire system for support. Use them as a screen or focal point on a pillar or wall.
• Species roses are the oldest type of roses. They’re popular for toughness, hardiness and easy care. Many are single- petaled and/or have interesting foliage and hips. Some bloom just once; rugosa roses are repeat bloomers. Need an outstanding, large, xeric shrub rose? Try part of the Plant Select program that tests plants in Colorado conditions.
• Hybrid tea, grandiflora and floribunda roses tend to need the most care in watering, deadheading and fertilization, but are excellent for cut flowers, consistent bloom and color all through the garden.
• Miniatures grow well in containers or in the front of the border.
• Old garden roses, technically a class grown before 1867, come in many sizes and bloom types; many are fragrant and have decorative hips that give the bush fall or winter interest.
• Shrub roses, a general catch-all term for roses that don’t fall into the other types, can be used as borders and groundcovers. Many in this group are cold hardy even to Zone 2.
• David Austin English roses are popular for their fragrance, large blooms and wide color range.
LAWNS
• Have you aerated yet? Twice a year isn’t too often, especially in compacted soils or old lawns. Once you’ve aerated, fertilize, then water it in if your lawn isn’t already spongy from recent rain.
• For the first mow, cut high: 2½ to 3 inches. If the grass is really tall, make two passes, with the lowest at 3 inches.
• Yes, it seems as though you’re always mowing. This is normal in spring, as the grass is growing quickly.
• Leave clippings on the lawn to put valuable nutrients back into it. This practice does not lead to thatch buildup.
Betty Cahill: gardenpunchlist.blogspot.com
