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Index : Flowers - Perennials
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- 12. Desert Rose Care - Top
- One of the most important aspects of rose care here in the desert is watering. Roses need frequent irrigation during hot weather. In the spring, two to three waterings weekly are required when daytime highs are in the 80's and lower 90's. As temperatures approach 95 F. increase watering to three to four times weekly.
Flood or drip irrigation may be used to water roses. But regardless of the system you use, make sure the water penetrates to a depth of 2 to 3 feet. This deep watering not only stimulates deep rooting of your roses, but also keeps harmful salts washed down below the root system.
The best way to determine the depth of wetting is to measure the moisture level immediately after an irrigation cycle. To do this, use a metal rod, such as a two foot long re-bar which can be purchased at hardware or building supply stores. When the soil is moistened, the rod can be pushed in to the soil. Try pushing the rod down in several locations. Because of rocks and other soil debris, the probe may strike one of these objects and give you a false reading. Try another spot. Pull the rod up and measure the depth it penetrated. The rod should go down at least 2 feet. If it didn't, adjust your drip irrigation to run longer or fill the basin deeper, and then test again.
To help conserve moisture and keep rose roots cooler, cover the soil with an organic mulch. Straw, compost, chipped bark, ground western cedar, and pine needles all work well. They insulate the soil from heat and slow moisture loss better than rock mulch. To be most effective, the organic mulch layer should be 3 to 4 inches thick.
Besides abundant water, roses need heavy amounts of plant nutrients to stay healthy and happy. In particular, they respond to regular applications of nitrogen and phosphorous. Magnesium in the form of Epsom salts has also been touted by rose experts as a way to promote basal shoot development and overall health.
The form nutrients take can vary. Quick release, slow release and organic forms all have their place and one may not be better than the other. In my opinion though, the slow release forms of nutrients make the most sense. That's because they release a constant but mild level of nutrients. This avoids the ‘feast or famine' condition that can arise when using standard granular fertilizers such as ammonium phosphate. Keep in mind that slow -release fertilizers used here in the desert only last half the time indicated on the package label. So a 3 month timed-release product will last just 6 weeks.
If you use a standard granular fertilizer or rose food, make applications of these every 4 weeks up to June. Then cut the amount per application in half, from June through August, to allow roses to rest during the heat of Summer. The American Rose Society recommends a 10-10-10 or similar analysis fertilizer.
Roses can also be supplied their nutrients in organic form. The American Rose Society calls for the application of: one cup bone meal, one cup cottonseed meal, one-half cup blood meal, one-half cup fish meal, and one-half cup epsom salts per rose bush. This spring application should be followed up with an application in September to promote Novemberl flowering.
Liquid fertilizers can be used to supplement your rose fertilization. Products like Peters, Shultz, and Miracle-Gro can be applied to bolster the plants nutrient levels as needed through the season. In addition, roses may require periodic applications of iron. If new leaves have yellowed, apply ‘chelated' iron to the soil.
Be on the look out for rose pests this spring including; aphids, mites and cane borers. Aphids are soft-bodied green insects that attack soft new growth, causing leaves to curl. They also secrete a sticky substance called ‘honeydew ‘ that imparts a varnish-like shine to leaves.
Mites are tiny, pencil-point sized, pests that attack the plant from the bottom and work their way up. Leaves become stippled with yellow specks from their feeding and eventually fall off.
Both mites and aphids can be controlled with a weekly hosing off with a strong jet of water from a hose-end attachment. Spray both the top and undersides of leaves.
Rose cane borers can be prevented by applying a wood glue to any pruning cuts. This will seal the wound and prevent the borer larva from entering and feeding in the stem.
Visit the new Rose Garden at the Pima County Extension Office. It will be one of many stops on the upcoming Master Gardener Home Garden Tour scheduled for Saturday, April 10th. Tickets are available at Harlow Gardens, Rillito Nursery and at the Pima County Extension Office.
"Collectibles and Antiques as Container Gardens" will be the topic for this week's garden demonstrations. They will be presented on Wednesday at 9 a.m. at the Pima County Extension Center, 4210 N. Campbell Ave (central); and at 1 p.m. at the Wilmot Library (east), and on Friday at 1 p.m. at the Oro Valley Public Library (northwest).
Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona, 520-626-5161. - Updated: March 28, 2004
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