To grow roses in the arid Southwest, irrigation must be practiced. In some sections, such as from Laredo to Brownsville along the Rio Grande or in the Salt River area of Arizona near Phoenix, rose flowers can be had almost the entire year.
In these areas, the period of frost danger is seldom more than a few days to a month each year, and planting of rose shrubs is preferred during this so-called winter period.
In other sections or zones of the arid Southwest, for example in Amarillo, Albuquerque, and similar places where the January average temperature is 32° to 35° degrees Fahrenheit and temperatures below zero are expected each year, planting is delayed until February or early March.
Even in these areas, particularly choice, colorful and fragrant blooms do develop in the cooler months of the growing season. In both the warm and cold sections of the arid Southwest the occurrence of black spot is practically unknown.
Sunlight is readily available in most of the southwest area, and roses will tolerate full sun if they are not crowded close to the south side of a building.
They will also succeed if the beds are located to receive as little as six hours of sunlight a day. A planting site partial afternoon shade is very desirable, especially if it also affords some protection from the wind.
The wind can be as damage the blooms and foliage as a scarcity of water.
Rose Varieties Depend on Local Conditions
The selection of varieties depends on local conditions and what you expect from a rose.
Plants in warm climates produce small flowers with fewer petals and less color intensity than the same varieties in cool climates. Many gardeners in warm climates are satisfied with the flowers knowing that the flower quality becomes better with the arrival of cool weather.
If extreme hardiness and little care is your aim in selecting roses, your planting might consist of the historically popular climber Paul’s Scarlet, with its tremendous display in early spring.
Climbers such as ‘Mermaid’ roses withstand black spot infection but cannot endure hard freezes.
Rosa Queen Elizabeth introduced in 1954 is a beautiful, award winning grandiflora type noted for its hybrid teas shaped flowers borne in clusters and held on long cutting-length stems.
There are many varieties in the floribunda class of roses from which to choose. These all bear clusters of small-sized flowers with short stems.
Southwest Rose Growing Tips
Planting Roses In The Southwest
Perhaps the most important point in planting in the arid Southwest is to keep the branches out of the soil. Set the plants so the bud union (the point where the branches originate) is above the surface of the ground during the growing season.
It may be desirable where winters are severe to mound soil up around the canes 6″ to 8″ inches, but this soil must be removed in spring. If hot summer heats the soil the canes may be burned and the plants killed.
Watering Roses in The Southwest
How and when to water roses are important considerations. Watering should be thorough so that it penetrates the soil surface 8″ to 10″ inches deep into the root ball.
This means that with good drainage flooding the beds with 2″ to 3″ inches of water should be sufficient.
Overhead sprinkling can be practiced in arid climates, except during midday, without causing black spot if the disease is not already present.
Even in semi-arid climates, sprinklers can be run all night (we still like soaker hoses to deep water roses) without black spot spreading as long as an application of a suitable fungicide is made and drying occurs the following day.
This has been demonstrated to be true in both garden and field trials. Ordinarily, once-a-week watering is ample to maintain growth in dry seasons.
Southwest Disease and Insect Control
Powdery mildew is a major disease, especially when warm days are followed by cool nights. Check with your local county agents for the best control options.
If black spot gets a hold, weekly spraying with captan, maneb or zineb fungicide is advised.
In applying any of them be sure to cover the lower side of the foliage. Neem oil or Malathion is used when aphids, beetles, and other insect problems arise, but red spider mite is best controlled a biological control. A fungus beauveria bassina or a beneficial type of red sipder Phytoseiulus.
Fertilizing Roses in the Southwest
A good fertilizing method is to use one of the pelleted or granular materials in a shallow trench or on the surface of the ground around the rose bushes and then water it in.
When new growth starts in spring, but not at planting time, fertilizers such as 12-24-12 or 10-20-10, which are almost completely soluble in water are safe to use at the rate of only one cup for twenty bushes, applying every six or eight weeks until fall.
Cultivating and Pruning
Because rose roots are generally shallow and spreading, cultivation should be only an inch or two deep and just enough to kill weeds.
A loose mulch, such as pine needles, ground corn cobs, or even sawdust, will aid in weed control and conserve moisture.
General pruning back should be done in late winter except for the climbers, which are pruned after spring bloom.