Las Vegas is perfect place to grow roses if they are kept healthy

Roses are a good choice for our Las Vegas climate and soils if kept healthy. If they are not healthy, they suffer in intense sunlight, summer heat and soil problems. When roses are healthy, they can handle a lot of abuse. If you are lazy gardener like me, you will plant them in the best location, get them off to a good start and surround them in an environment they prefer.

Just like any landscape plant, fruit tree or vegetable variety, some roses perform better in the desert than others. Some roses such as the large, white and yellow-flowered Lady Banks types of roses are single bloomers, meaning they bloom only once in the spring. Other times they are just large and green.

Most beds of roses favored among homeowners were selected and bred to continuously bloom when growing well. These roses come in a variety of colors and range in the strength of their rose aroma.

Selecting roses that perform better under desert conditions reduces future worries and work. Consult recommended varieties online through Weeks Roses Inc. or by calling the local cooperative extension office help line for the varieties the experts recommend in the desert. If all else fails, you can email me, and I will provide you a similar list of select varieties that not only look good but smell good and grow best in our desert environment.

Can you plant roses in hot landscape locations? You can if these roses are kept healthy. In hot locations, roses bloom all winter long yet suffer through the heat of the summer. I frequently tell people that our winter is our summer. But roses, in general, grow best planted where they receive full morning sun yet shade from the late afternoon sun during the summer.

What about surrounding them with rock? Roses don’t like rocky soils in the long run, but rock works if roses are kept healthy. Just like vegetables, roses prefer growing in biologically active soils amended with compost at planting time and the soil covered with wood chips. These wood chips, unlike rock, continue to rot and decay continuously adding to the biological activity of the soil. If roses are growing in rock, water in a light application of finely screened compost in the early spring with fertilizer and iron.

The schedule for maintaining roses is to prune, spray and fertilize in January. Roses’ first fertilizer application of the year with iron is done in January. Using a good quality compost for soil improvement and a fertilizer application makes it easier. After pruning is finished, a dormant oil application would be a good idea, also applied in January.

Q: I have several mature rose bushes that are about 10 years old. How much growth can I remove and still keep them thriving?

A: Without seeing your roses I would guess anywhere from 1/3 to 2/3 of its total size. Start with a sharp and sanitized hand pruner or loppers. Pull off any leaves still attached to the canes if present. In warm climates like ours or warm landscape microclimates, all of the leaves may not be gone when you prune. Removing the leaves, it is said, helps speed up dormancy. Removing the leaves also helps you to see the architecture of the shrub.

Leave anywhere from 12 to 18 inches of growth remaining when you are finished. Whenever possible, leave behind six to eight strong, undamaged main stems growing in different directions like spokes on a wheel. Remove any weak growth from the remaining canes or strong growth coming from the graft or below it. Growth coming from the graft or below usually grows straight up so it can be pretty easy to recognize.

Pruning classes are conducted by rosarians in January. I will let you know in my column where and when as soon as I find out from them.

Q: My Lincoln roses are about 5 feet tall. Should I cut them back or just cut the leaves? If so, to what height should I cut them?

A: Mr. Lincoln variety? Mr. Lincoln hybrid tea rose is an excellent variety for this climate — red flowers and very fragrant. It was released in the mid-1960s from Weeks Roses by a great rose hybridizer, Herbert Swim. Mr. Lincoln is one of my favorite roses for the desert with another hybridized by him, Double Delight, and released by Armstrong Roses.

The plant normally goes dormant in January when it is pruned back by about two-thirds. If it hasn’t gotten cold enough, which forces leaf drop, pull all the leaves off after pruning. Make sure your pruning shears are sharp and sanitized.

At the end of January, apply mulch, compost and your favorite iron fertilizer for the year. If you don’t use any compost or it’s not a rich compost, then apply a good rose fertilizer as well.

Q: I planted these two Show Pot tea roses in early February. The stems are green, but there is no growth on the stems. Any idea when can I expect to see some growth?

A: Unless you are a rose fancier, a rosarian for instance, and wanted to do some rose experimentation, stay away from so-called specialty roses such as these tea roses and other shrub roses. There are hundreds you could play with.

The most common roses planted by homeowners are categorized as modern roses such as hybrid tea and floribunda. These are the types of roses and varieties that satisfy most homeowners. They usually bloom multiple times during the year and many of them are fragrant. Tea roses were crossed with perpetually blooming roses to give us today’s hybrid tea rose, a modern rose type.

If rose experimentation is your bag and you are prepared to care for a rose that might struggle in this desert environment or even die here, then plant it on the east side of a wall or building or in some filtered shade. Be sure to amend the soil with compost and cover it with 3 to 4 inches of wood chips. Give it every opportunity to perform at its best in this harsh environment. Any added stress placed on it by growing it in an excessively hot location, extremely high or reflected light, low humidity, wind and poorly improved soils might contribute to its poor growth.

Q: When should I fertilize my roses?

A: Roses growing at our cold, 2,000-foot elevation desert environment should be fertilized just before spring growth and flowering and again just before fall growth. If you are a rose aficionado, a rosarian or someone growing roses for show, you might choose to fertilize your roses differently than this.

In our location, this would be late January and again sometime in late August or September. Twice each year, avoiding the application of fertilizers during the hot summer months, is enough for most homeowners and most roses if they aren’t growing in containers. Roses grown in pots or containers receive less fertilizer but fertilized more often. Iron applications to the soil are done once a year as part of the early spring fertilizer application. Any rose or tomato fertilizer will do.

Q: What are the most common insects and diseases found on roses growing in the eastern Mojave Desert?

A: As far as insects go, the most common insects are aphids and cane borers (aka stem girdler) in the spring months. Aphids are controlled most effectively by dormant oils applied as a preventive spray in midwinter. Secondarily, controlling ants in the area, which contribute to the spread of aphids, can also be important.

Also occurring early in the year and creating damage are the stem girdlers (or cane borer), which can cause entire canes to die. Rose aficionados apply Elmer’s glue to the cut ends of stems after pruning as a preventive.

I receive the most questions about leafcutter bees that cut circles in the leaves. I will get emails starting in midspring (about April) with complaints about leafcutter bees on roses, bougainvillea, grapes, basil and other plants with tender spring growth.

Don’t bother controlling them as they don’t cause excessive amounts of damage to the plant. But leafcutter bees can create a lot of visual damage. Not sure what you can do about that.

Diseases aren’t common on roses because of our desert’s low humidity. Probably the most virulent and damaging disease can be fire blight, which is more commonly seen on quince and Asian and European pear.

Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.