Watering Drip by Drop Is the Slow but Sure Method

If the garden is going to need watering any month, it’s in August. The combination of heat and lush plant growth quickly dries the soil.

Do not try to water by standing with hose in hand, directing a shower of water onto your tomato plants. This is one one of those tasks that satisfy some gardeners but do nothing for the garden.

Even if you find such a pose relaxing, you probably don’t have the patience to stand there long enough to do any good. Check the soil after watering by scratching down with your finger to see how deeply it has been wet.

In general, plants need about an inch of water a week, but how that water is applied separates gardeners into two camps. In the high-tech camp are those who use drip irrigation. The essence of this system is simply an inexpensive plastic water pipe laid on the soil along which are emitters that slowly drip water.

It takes a long time to soak the soil a drip at a time, but dripping is more efficient than sprinkling because the approach pace a which plants use water. Water dripped near the roots of a garden plant does not feed weeds, is less subject to evaporation and doesn’t wet the leaves.

With a relatively inexpensive timer, a drip irrigation system is easily automated to turn water on and off a few times every day--spreading a weekly equivalent of 1 inch per week over the daylight hours of all seven days.

The traditionalist camp of gardeners water with sprinklers. The idea is to flood the soil, let it go half dry and then flood it again. But sprinkling is less efficient than drip irrigation because some of the water in the soil that follows each flooding is just pulled away by gravity, unused by plants.

Applying water at a rate to replace what a plant uses--as is done with drip irrigation--is not a good idea with a sprinkler because the continually wet leaves would be subject to disease.

With a sprinkler, you apply that inch depth of water once a week. To determine how long you have to run your sprinkler, set some cans around the garden, turn on the sprinkler and see how long it takes to fill them to 1-inch depth.

That 1 inch of water per week is equivalent to about 2 quarts per square inch. So for other types of watering--whether drip irrigation or dribbling water from a hose near the base of a young tree--determine how fast water is being discharged and estimate its spread in the soil.

Drip emitters usually specify their flow rate. Assume the spread of water in the soil near an emitter to be a circle of about 18 inches, somewhat less for sandy soils and somewhat more for clays.