FOR HOT-WEATHER LAWN IRRIGATION, TIMING IS EVERYTHING.
During a heat wave, how much should I water and at what time of the day (or night)?
It depends on what you are watering. In scorching weather, a lawn should be watered in the morning every day except the days you have it cut. You do not want to mow wet grass since doing so results in an uneven looking lawn and dulls the lawnmower blade.
It also takes a lot longer to mow through grass when it is wet, whether from irrigation or morning dew.
If you have spray sprinklers, you should water your lawn 10 minutes a day.
However, these 10 minutes should be divided into two irrigation applications of five minutes each. The reason for this is that, after five minutes, the microscopic pores in between soil particles become full of water. It takes a full hour for the water applied during five minutes of spray irrigation to drain through the soil.
Let's say you have three spray-irrigated lawn areas. You would program your time clock for two watering cycles, an hour apart, with each area set to water for five minutes in each cycle. For example, you could have the sprinklers come on at 4 a.m and 5 a.m., in which case they would shut off at 4:15 and 5:15 a.m.
If your lawns are watered by slow-moving rotary sprinklers, you will have to increase the irrigation time of each area to 15 minutes per cycle, since rotary sprinklers deliver water three times slower than spray sprinklers. Thus, each lawn area watered by slow-moving rotary sprinklers requires 30 minutes of irrigation per day during hot weather.
In our dry climate, you can safely water any time after the sun goes down and before the sun rises. Late night or early morning watering is preferred because when plants are fully hydrated and stress free just before the sun comes up, they are most efficient at making sugar, their energy source for growth. The hours from 7 to 10 a.m., before the heat of the day sets in, are most propitious for making sugar in the light-dependent biochemical reaction that drives photosynthesis.
While annual flowers should be watered daily, most perennials, ground covers, shrubs, and trees, especially when mulched, will do fine being watered every other day or less. The best test for determining how often to water is examination of the soil at a 2-inch depth.
Often the soil on the surface is bone dry but, when you dig down an inch or two, it is moist. In such cases, watering can wait.
One of the conundrums of watering are irrigation zones that include both lawn and ground cover, or lawn and perennials, or lawn and shrub beds. In such mixed zones, the ground covers, perennials, and shrubs are typically overwatered since lawn grass requires abundantly more water than these other plants.
Under such circumstances, either the lawn or the plants must be removed and replanted or the sprinkler system redone. The goal is to achieve uniformity of water requirement among the plants selected for each irrigation zone.
Irrigation zones should also be separated by sun exposure. Shade plants demand a watering regime that differs from that of sun plants.
Of course, you can make your life simple by selecting drought-tolerant plants that require little water even during the summer. A mature bougainvillea, for instance, may never need to be watered. Fruit trees planted from 15-gallon containers will require no more than two weekly soakings their first year in the ground and one weekly soaking by their second year.
I once saw a sunny, average-sized front yard (around 25-by-35 feet) that had been turned into a planting of a dozen semi-dwarf citrus trees. This mini-orchard not only provided luscious fruit throughout the year, but required significantly less water than a lawn.
Tip of the week
If you have daylily (Hemerocallis) clumps that are looking shabby, forget about the tedious job of pulling out individual dry or yellowing leaves one by one. You can simply cut the entire clump of daylilies down to the ground. Within two to three weeks, you will have significant regrowth, with fresh green leaves shooting up where old withered leaves had been.
This same procedure works with society garlic (Tulbaghia), fortnight lilies (Dietes) and liriope.
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|Publication:||Daily News (Los Angeles, CA)|
|Date:||Sep 8, 2007|
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