Aerate lawn to encourage deep roots

There are three upcoming events that might interest many of you. The first is a seminar about olive oils, the second one is about growing vegetables hydroponically in a greenhouse, and the third is about new rose introductions. All of these seminars are sponsored or co-sponsored by the University of Nevada Cooperative Extension.

Slow Food Las Vegas, part of an international nonprofit organization dedicated to helping people appreciate the connection between good food and sustainable production practices, will present its first seminar from noon to 2 p.m. Saturday at Nora’s Wine Bar & Osteria, 10301 S. Rampart Blvd., in Summerlin. The topic will be removing the mystique surrounding olive oils and helping participants make good selections.

For the following week, I invited a hydroponic greenhouse producer from Arizona to discuss growing hydroponic vegetables in the hot, Southwest desert. The seminar will be from 7 to 9 p.m. Tuesday at the Lifelong Learning Center, 8050 S. Maryland Parkway.

On Feb. 28 at 7 p.m., Christian Bedard will discuss Newest Rose Introductions Now and for the Future at the Lifelong Learning Center. This is a rare appearance for Bedard, a rose hybridizer with Weeks Roses, who recently won praise for his newest introduction, a miniature rose called Coffee Bean.

All of the seminars are free and open to the public, but reservations are recommend. Further information or reservations are available by contacting me at morrisr@unce.unr.edu or 257-5509.

Q: Is it the opportune time to aerate, fertilize and seed an existing lawn for the summer months?

A: Generally, you can aerate anytime a couple months prior to hot weather; this encourages deeper rooting, which in turn helps improve drought resistance. After aeration, it is best to apply a moderately high-phosphorus fertilizer, which also helps improve root development.

Seeding cool-season lawns is best done in the fall months from about mid-September to mid-October. The second best time is after soil temperatures reach about 50 F, usually around the middle of February to the first week of March, depending on soil type and its exposure to the sun. Seeding can be done earlier in hotter parts of the yard.

Fertilize a cool-season lawn like tall fescue three times a year: Labor Day, Memorial Day and Thanksgiving. Fescues do not require frequent applications of fertilizers. Other grasses like bluegrass or ryegrass need to be fertilized more frequently. I usually avoid applications during the hot summer months on cool-season grasses. Use a 21-7-14 fertilizer with half of the nitrogen in a slow-release form. Manure-based fertilizers give the best results but are more expensive to use.

Warm-season grasses are a whole different story. Grasses like Bermuda or Buffalograss like the heat. Because warm-season grasses are dormant during the late fall, winter and early spring, focus maintenance activities like the above during the hotter times of the year.

One activity you forgot to mention is dethatching. Dethatching is the removal of dead grassy materials from the soil surface of a lawn using a vertical mower, sometimes called a dethatcher. It is best to dethatch in the fall rather than the spring. This is because there’s a higher chance of weed invasion in a lawn during the spring months than the fall months.

Q: I am trying to find information about two plants: the Baja red fairy duster and bottlebrush. Both were planted in the fall of 2007. The fairy duster was damaged by jackrabbits even though we used a garlic spray that was recommended. Both plants seem damaged by the cold winter.

A: The Baja fairy duster, called tabardillo or zapotillo in Mexico, is native to the Baja Peninsula south of California. It is here that it survives on gravelly soils, hillsides and washes. At temperatures below the mid-20s this plant will be damaged and possibly freeze to the ground. The damage is much worse if planted in open locations subject to winds.

I don’t know where you live, but the fact that you have jackrabbits makes me believe you live in an area that has been recently developed. Weather conditions on the fringes of the valley where there are new developments are typically harsher in the winter months than in areas close to the center of the city.

As an example, our research facility in North Las Vegas, which is exposed on two sides to the open desert, achieved a low this winter of 14 F while some volunteers who live close to downtown Las Vegas had backyards that never saw freezing temperatures. Most likely, these warmer temperatures have much to do with the urban heat island effect.

Your fairy duster was probably damaged this winter by low temperatures. You will have to wait and see if you get new growth or not.

The Baja fairy duster can reach sizes of 4 feet tall and 4 feet across. They will take heavy browsing damage and more cold once they are established but not while they are young. It will be important for you to protect them from winter cold or move them to a warmer location in the yard out of the wind.

There are several different bottlebrushes and I do not know which one you have. The weeping bottlebrush will not handle very much cold at all while the lemon bottlebrush will handle a bit more cold. Just like the fairy duster, this plant will be damaged or maybe killed if planted in an exposed part of the yard and by low temperatures.

The other problem with many of the bottlebrushes is their susceptibility to yellowing or iron chlorosis. Fertilize these plants with an iron chelate in the spring prior to new growth.

You will have to wait and see if these plants come back this year. I would not prune anything until you see new growth.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at extremehort@aol.com.