Ethel M botanical garden light display features 500,000 lights

Each year for the past 10 years employees have strung more than 500,000 holiday lights for visitors to enjoy. The facility covers more than 3 acres and features more than 300 species of plants suitable to our desert environment. It is one of the oldest and best examples of desert landscaping in the valley.

Q. With all the beautiful rain that we had recently, what should we do regarding future watering? Has it been enough water to just stop watering until after the first of the year?

A. Rains come in all forms. This one was rather unique in that it came down over a nice, long period of time giving it a chance to soak into our landscapes instead of running off the surface and into the streets.

Landscapes are supposed to be contoured to force rain off landscapes and into the streets. Once water enters the streets they act as “storm sewers” and help remove water from properties. If landscapes are not contoured correctly it is feared that water might accumulate on the landscape and flood homes, causing damage.

For gardeners who are interested in “harvesting” water on their property, this rule may seem to be counterproductive but it is meant for the “general good.” There are ways to store water and improve the effectiveness of rainfall such as dry stream beds and pools, but you must be careful when doing this. I will post some ideas on my blog as examples.

As a general rule we consider about 40 percent of our rainfall to be what we call “effective.” This means that 40 percent of the rain, four-tenths to every inch, actually gets into the soil where it is stored rather than running into the streets. This rain event however was more “effective” than most.

Another problem was that the rain was not evenly spread throughout the valley. This makes it hard to make a general statement about how long to turn off irrigation systems.

For shallow rooted plants like flowers and turfgrass they will still need a couple of irrigations the rest of this year. Deeper rooted plants, such as trees and large shrubs, can probably get by.

Unless you know your rainfall amount, I would count this rainfall as a single irrigation event, skip one irrigation and then continue irrigations unless we get more rain. The savings will still be significant.

Q. I believe you made an error last week about the Chinaberry tree. You said it “is also called Persian lilac and in the United States we sometimes call it the Texas umbrella tree.” I do not believe that the Persian lilac is related at all to the umbrella tree. We had both in our yard years ago, and they were quite different.

A. Thanks for your comment and you are right, there is more than one plant called “Persian lilac.” This is where the common names can be confusing.

The Chinaberry tree (Melia azedarach) can also be nicknamed the Persian lilac because of the perfumy flowers it produces in spring. You can Google any of these names.

There is another plant, also called Persian lilac (Syringa x persica), a hybrid lilac closely related to common and Chinese lilac, which is probably what you were growing.

We have the same problem with another plant we call mock orange. Locally, our mock orange is a Pittosporum. This is not the same mock orange known by most of the country. When I was in school, mock orange was a totally different plant with the scientific name Philadelphus coronarius, a flowering relative of hydrangea whose flowers were used for garlands because they have a strong citrus fragrance.

I do not to use scientific names in my column but common names can be confusing for this reason.

I appreciate these comments because I’m sure others were thinking the same.

Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com.