GARDENING: Help your lawn deal with the extreme Las Vegas heat

Regarding lawns in Las Vegas there are a few things you can do about the extreme heat if you haven't done so yet. First aerate. Aeration will help get the roots down deeper and improve your lawn's ability to withstand drought. Actually, this should have been done earlier but if you haven't done it yet then it should be done. Aeration is particularly needed if you see any standing water, runoff or on slopes or heavy traffic areas.

Lawn areas should be aerated in preparation for the heat. Aeration can be done safely anytime of the year while dethatching is best done in the late fall. Get the mowing height up now for a deeper root system.

Secondly, follow aeration with a fertilizer high in phosphorus and potassium. I normally recommend a fertilizer high in nitrogen and low in phosphorus and moderate in potassium. But following an aeration is a great time to get phosphorus into the root zone. And since phosphorus doesn't move through the soil easily it will help to apply it after aeration.

Phosphorus also improves root growth, which is why you are aerating now. The potassium is to help in drought stress. If you haven't fertilized for quite a while then give yourself a high nitrogen fertilizer as well.

The last thing you want to do preparing for the heat is to get your mowing height up to 2 and one-half inches or higher. It will encourage the roots of the grass to go deeper, particularly if it's done after aerating and fertilizing.

If the weather suddenly turns hot, dry and windy the plant may be caught off guard by these sudden changes. The leaves and stems, formerly acclimated under cool weather, are now abused in the harsh new environment of our Las Vegas summer. The leaves that formerly were doing quite well now can't tolerate the harsh and sudden changes.

Remember now is the time that many of our larger insect pests, like borers are active. Of course the best protection is having a healthy plant, but there are things you can do such as not exposing larger limbs and young trunks to direct sunlight. So try not to do any major pruning now until fall. Pruning now also exposes young limbs that have not formed any bark to direct sunlight, which in these light intensities oftentimes causes sunscald. This is the time of year that we should be protecting those trees and large shrubs from potential borer problems.

Watch for cutworm damage in vegetable and bedding plant areas. Reports have come in about seeing scads of so-called miller moths, which is the adult form of a variety of cutworm. Cutworms, as their name implies, cuts young succulent plants off at the soil level during the night and retreats into the soil during the daytime.

Usually you can see pencil-sized holes drilled into bare soil surfaces where cutworms are active. Usually insecticides are used for control, but mechanical control methods like planting collars around vegetables work well and there are reports that diatomaceous earth works as well but has no scientific documentation to support it.

The cool, wet weather of spring caused some other problems for us as well. Bees don't like to fly during cool, wet weather. If bees aren't flying then there will be poor pollination. Look for the results of poor pollination on fruit and nut trees, as well as your vegetable garden.

The results of poor pollination will be early, sudden fruit and nut drop before they can mature. Since the bees did not pollinate the fruit and nuts then the seeds cannot mature inside the fruit or nuts. Most fruits and nuts need seeds to develop because the seeds send chemical signals to the fruit and nuts that allow them to develop and mature. Of course, there are exceptions such as the seedless grapes and watermelons. But for most fruits and nuts, even though small fruit or nuts may form, they will not continue to maturity since the seeds inside were never formed.

The same is true of vegetables that result from a pollinated flower. Vegetables such as tomatoes, peppers, squash, cucumbers, melons and the like all result from pollinated flowers. Even if the vegetable flower is not pollinated, a small vegetable fruit may result. But, like the fruits and nuts mentioned above, it will not contain seeds that can take this fruit to maturity.

Soon after this vegetable fruit begins to develop and the gardener sees and gets real excited, this fruit withers and dies. The natural response is to think it was a disease or blame the nursery for selling bad plants or your neighbor. When things like this happen, stop and think. What was the weather like a few weeks before this happened? Without bees, all of our gardens would fail.

Question: I am looking for an evergreen plant that I can use between the road and yard. I have an area that is about 6 feet wide.

Answer:There are a number of plants that will do this job. Some of this depends on location. If this were in semi-desert, like on some of the horse properties in the northwest, then desert-adapted plants would be better than others. There are so many that I don't know where to start. Refer to a book called "Plants for Dry Climates" by Rose and Duffield or you can call the Master Gardeners at 257-5555, and they may have a list of plants that can be mailed to you.

Remember that each plant uses water and that generally the bigger the plant the more water it uses. One of the best that suits your needs, but one of the most controversial, is the oleander. It is very tough, flowers, evergreen, few diseases, few insects, flowers are in numerous colors, excellent dust catcher if dust is a problem, but it is poisonous. Takes any location and any exposure except deep shade. Personally, this is probably one that I would put at the forefront of a list. There are many landscape plants that are poisonous.

You can use Lady Banks Rose, yellow or white, against a fence and use it for support. It will get huge, maybe 10 feet tall, and weep over the fence. It is thick and dense, but will lose its leaves in the winter but still creates privacy due to the thicket it produces. Most vines will just cling to the fence. You could put slats in the fence and cover it with a vine. If this is what you want then you can use Japanese Honeysuckle and others, but most are deciduous. Ivies need a bit of protection so in harsh exposures they aren't a good choice.

Take a look at Sugar Bush, the larger forms of Texas Ranger, some of the brooms like Scotch Broom, Mediterranean Fan Palm (untrimmed), some of the cassias, mescal bean, sweet acacia grown as a shrub, and many others. I hope this helps.

Question: You've helped me before in the past and I hope you can now as well. Every time it rains, we have a mass exodus of worms from our grass. These worms crawl up our concrete slab toward the house and number well over 100 each storm. It's actually kind of a scary sight! My husband and I laid the fescue sod three years ago ourselves; we have not aerated or dethatched the lawn.

We follow a watering schedule and the worms don't appear after regular watering. Is there a solution to keeping them in the lawn? I don't mind the worms so much, but they dry up on the concrete and I need to use a square shovel to get them off -- it ends up being quite a bit of work.

Answer:This has been a problem in other older communities where earthworms have become established, but this is the first time I have been asked about them in Las Vegas. And I know what you mean I have seem them in large enough numbers to create problems. In some lawns with older people they can become a hazard when they leave their burrows piled up on the lawn and have caused accidents for older folks. I know you realize the benefits that earthworms provide for your lawn and gardens.

They are far and away much more valuable than the occasional nuisance they might be. They provide aeration to the soil, help decompose organic material and supply nutrients to plants. The reason they surface is because they are literally drowning after a rain and come to the surface to avoid that.

In the past what I have recommended is to aerate deeply and regularly particularly before any times rain might be a problem. For us this might be during the winter months more than the summer months. The second thing you might try is to apply sulfur to the lawn. Years ago there was some research done at Washington State University that provided some evidence that sulfur helped to lower earthworm populations. The reason why was not known. I believe the rates were up to 10 pounds per thousand square feet of lawn. This should be avoided during hot times of the year. There are no recommended pesticides for use against earthworms and should not be used anyway for that purpose.

The other less practical reasons are to convert to a desert landscape or open a bait shop. Of course I am joking about the bait shop.

Bob Morris is a horticulture specialist with the University of Nevada Cooperative Extension.


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