Desert landscape can be preferable to grass, trees

      The following are typical questions our Master Gardeners answer daily at the Nevada Cooperative Extension. If you have gardening questions, call the Master Gardeners' hot line at 257-5555 between 9 a.m. and noon Monday through Friday.
     
      Question: Why would anyone change over their yard from grass, trees and shrubs to a desert landscape?
      Answer:One reason is that it's more fun. You can still have grass to play badminton, throw the football, a place for the dogs or just have a picnic.
      Get rid of those areas where grass isn't needed and save money. Homes sell better when the yard is attractive and water efficient. But do it right. Doing it wrong can cost you money in terms of the curb appeal of your home, an increase in air conditioning costs and an unfriendly yard. Learn how to do it right.
      Our class on retrofitting your landscape began Tuesday at our office at 2345 Red Rock St. Those interested in future classes can call the Master Gardeners at 257-5555.
      The Master Gardeners are now available to answer phone calls on Saturdays. Every second and fourth Saturdays Master Gardeners will be available for phone calls from 8 to 5 p.m. at the same number.
      Question: Why is my tall fescue lawn brown now?
      Answer: The lawn did not have enough nitrogen fertilizer going into the cold temperatures. Basic rule of thumb is that lawns stay greener, longer if the grass has a high nitrogen level when it turns cold.
      What can you do now? There is frequently a warming spell here in mid to late January. This will encourage fertilized grass to grow and turn green. Now is the time to put on a high nitrogen fertilizer on your lawn if you are to take advantage of this possible warming spell.
      The fertilizer should be high in nitrogen. The nitrogen should be a high percentage of "nitrate" type nitrogen. The contents of the bag will tell you what kind of nitrogen is inside and what percentage is present. Ammonium nitrogen is OK but it will be slower-acting than the nitrate form.
      The fastest way to get it green would be to spray on a liquid fertilizer high in nitrogen. Nitrate nitrogen can be "hot" to plants and burn them so don't apply too much. The other factor to consider is the kind of grass. Different grasses have different temperatures at which they turn brown.
      Fescue can stay green easily through winter temperatures above 20 degrees if properly fertilized with a high-nitrogen fertilizer. If air temperatures get below 20, fescue may not stay green regardless of how it was fertilized.
      At these temperatures, fescue is beyond its lower limit to stay green no matter what you do. Grasses, like bluegrasses, have a lower temperature limit than fescue for staying green and there are bluegrass lawns in town. Bluegrass lawns will stay green during low winter temperatures with less work than fescue lawns.
      However, bluegrass lawns have a considerable number of drawbacks here due to our hot, dry summers. Bermuda grasses are warm season grasses so they turn brown at relatively warm air temperatures. However, if Bermuda grass is fertilized with a high nitrogen fertilizer when it normally would turn brown, the nitrogen in the plant will keep the grass from turning brown early.
      The Bermuda grass will still eventually turn brown in our climate as it gets colder but it will stay green longer. This can be good and it can be bad. If you are trying to overseed the Bermuda with a different grass for winter color, keeping it green and vigorous long into the fall can lead to a bad overseeding job.
      If you aren't planning to overseed, then keeping it green long into the fall can be good. The same thing about winter color of fescue and nitrogen fertilizer is true. Fertilizers containing high nitrogen are best to apply just before cold weather if you want a lush green lawn through the winter. Remember each grass has its limit about what temperatures it can take and stay green.
      Q: When can I apply dormant oils to my plants?
      A: Apply dormant oils in the spring, at the first sign of warm temperatures, where insects have been a problem in the past. Interpret this to mean you would apply dormant oils when it gets comfortable to be outside without a jacket.
      Don't delay it beyond this point or you may lose its effectiveness. The terms, dormant oil and dormant spray, are often confused and they are very different from each other. Use dormant sprays for insect and disease control just prior to plant growth in the spring.
      Dormant sprays from chemical companies usually contain traditional pesticides. Dormant oils are refined oils, which are sprays applied to plants to suffocate insects that might be a problem in the coming months. These insects predominantly include aphids, scale insects that are in the crawler stages and mites.
      It is an excellent way to control these types of insects before they become a problem. The key to the oil's effectiveness is for these insects to be present and for you to apply it at the right time. Remember oils suffocate.
      Oils also evaporate and get washed off plants. You want the oil to last long enough to suffocate the insects. That means you want the insects to be highly susceptible to suffocation. Insects are cold-blooded. They are active when it's warm out and inactive, or "resting," when it is cold. When insects are inactive or resting, they do not suffocate quickly.
      Think of all the stories you've read about where someone is trapped under ice for an extraordinary number of minutes and they survive. They survived because slowed body activities demand less oxygen. Insects are like that when it is cold. They don't suffocate easily then and the chances are very high they will outlive the time the oil is effective and present.
      The key to an effective application of dormant oil is to apply it early in the year, during warm spells, when the insects will be active and need oxygen to survive.
      Q: When should I apply mulch to my landscape plantings?
      A: I would wait to apply mulches until the soil warms more, sometime just before it gets hot. Mulch is a material applied to the surface of soils as a surface layer. Mulches can be made from chopping or grinding wood such as tree limbs, Christmas trees or grinding out stumps that remain after a tree is removed.
      By the way, the best wood mulch in my opinion is from stump grindings. Some of the arborists or tree companies have stump grinders and either leave the grindings behind for people to collect or haul it to the dump. For a fee, they might haul it to your yard.
      Mulches can be made from crushing rock such as granite or sandstone and used for "desert" landscaping. Solid, clear, plastic sheeting is called plastic mulch and used in commercial vegetable production to warm the soil and get faster production from tomatoes, cucumbers and other high-priced vegetables. The cost of the plastic mulch is offset by the economic returns the grower gets by having the first vegetables in the spring.
      The benefits of mulch to landscapes are numerous. They conserve water. Mulches slow down the loss of water from the soil surface. They are very effective when using drip irrigation. They control many weeds. Covering the surface of the soil stops sunlight from reaching the soil surface where weed seeds are waiting to sprout.
      They stabilize soils. Water from overhead irrigation compacts soil as it hits the unprotected surface. Mulches act as a cushion and help prevent compaction. Mulches also regulate soil temperatures. Wood or rock mulches keep surface soil temperatures from wild fluctuations due to sudden or wide variations in air temperatures.
      In the spring, soil covered with a mulch are slower to warm than bare soils. This delays root growth in the spring. Roots growing in mulched soils in the fall grow longer into the fall because the soil does not cool as rapidly. Soil temperatures always lag behind air temperatures.
      Mulches just make that lag even longer.
     
     Bob Morris is a horticulture specialist with Nevada Cooperative Extension.