THE COASTAL GARDENER:

Last weekend was hot — 85, 90, even 100 degrees in some areas. It was the first hot few days of the year.

Lawns all over the area had a similar reaction to the heat. You probably noticed it too. Grass areas, maybe even on your own; showed dry, wilted, discolored or parched patches. Last weekend it seemed like every second lawn at homes, in homeowners associations or on city landscapes showed the same wilted patches. It was hard to miss.

Like clockwork, at the first heat spell every year we see these patchy, wilted lawns. It’s never the whole lawn that wilts, usually just small, irregular portions.

In the landscaping trade these dry lawn sections are called “hot spots.” But hot spots are habitually misunderstood and usually mismanaged. More often than not, a homeowner or paid gardener’s attempt to eliminate a hot spot is a very wasteful activity.

A “hot spot” is simply an area of your landscape that isn’t getting enough water, or at least isn’t getting as much water as the area around it. It is most obvious in lawn areas, where it is easier to notice than among shrubbery or mixed plantings.

Here’s how a how spot happens: An irrigation system turns on and waters for a while. With a casual glance everything looks fine — nice and wet. But in reality, some portions of the lawn are receiving far less water than other areas. If, after an irrigation, you took your shoes off and poked a long screwdriver into the lawn in several places you would find out just how irregular this “nice and wet” look really is.

During cool times of the year these irrigation irregularities are pretty well masked. But during the first heat spell of spring, the little patches of lawn that don’t get enough water stand out. A day or two of really hot weather and these little dry patches are wilting and beginning to brown. These are lawn “hot spots.”

Now that you know what these patches of lawn are, what do you do about them?

What most people, or their gardeners, do about a “hot spot” is to crank up the irrigation. The usual tactic to eliminate that little patch of dry, wilting grass is to apply more water. This means either watering longer or watering more often, or both. Bad idea. Cranking up the irrigation system is a mistake, a wasteful mistake that we can no longer make in a time of water conservation.

The mistake in setting the irrigation system to higher and higher output, until the hot spots finally go away, is that a huge amount of water is being wasted on the remainder of the lawn. It’s a failed strategy — a bit like turning the lights on in every room of a two-story house when you are looking for a coat in a downstairs closet. Why apply two or even three times more water to 90% of the lawn because 10% of it needs it?

Lawn hot spots are almost always the result of irregular sprinkler system coverage, but are sometimes caused by a small patch of unusually hard soil that takes up water more slowly or by a small rise or slope that causes the water to run off. If you water the whole lawn every time you really only need to water a hot spot, you’ll be over-watering every part of the lawn that isn’t a hot spot.

Better yet, to permanently eliminate a hot spot, start out by turning the irrigation system on and checking for a clogged head or one that needs a simple adjustment. If that doesn’t do it you may need to replace the head near the hot spot with one that covers the area more thoroughly. If still not resolved, you’ll probably need to add another head to the irrigation system, quenching the hot spot.

Until the situation is fixed permanently, a simple solution might be to hand water these dry spots or to add some supplemental water to the area with an old-fashioned sprinkler on a hose. But the solution is not to apply more and more water to the whole lawn when just a small portion needs it.

ASK RON

Question: What are the big, rounded shrubs with gray-green leaves I am seeing all over the area at this time of year? They bloom with tall cone-shaped spikes of blue-lavender flowers. They are quite striking.

Vicky

Newport Beach

Answer: You are describing a large shrubby plant called Pride of Madeira (Echium candicans). This is an easy plant to grow, very architectural and very handsome when used properly and given plenty of room. Pride of Madeira is a large plant and cannot be pruned to keep it in a small space. It is ideal for hillsides or for coastal bluffs where it can grow unobstructed and show off its architecture. It is native to a small group of islands off the west coast of far northern Africa, a climate very similar to ours in Orange County.

ASK RON your toughest gardening questions, and the expert nursery staff at Roger’s Gardens will come up with an answer. Please include your name, phone number and city, and limit queries to 30 words or fewer. E-mail stumpthegardener@rogersgardens.com, or write to Plant Talk at Roger’s Gardens, 2301 San Joaquin Hills Road, Corona del Mar, CA 92625.

RON VANDERHOFF is the Nursery Manager at Roger’s Gardens, Corona del Mar