How and When to Water your Garden and Lawn

Watering your yard, garden or lawn can be tricky. You must know when and how much to water. When to water depends on the root system and how much water will be needed for the amount of soil that has dried out.

When to Water

The best way to tell when to water is by inspecting the soil in the root zone. Plants that have shallow roots are the first to suffer if a drought hits because they can only take moisture from a small area of soil. Plants that are deeply rooted can withstand drought for a time because they can draw on a reservoir of water.

Root Depth

Turf plants have very shallow root systems. Root depth is never more than 3 inches. Leafy vegetables grow roots to a depth of 6 to 10 inches. Beans root about a foot in depth, corn approximately 2 feet, potatoes 18 inches and tomatoes and asparagus 3 feet.

Soil restriction such as poor aeration, high water table or hardpan decreases root depth. Trees and shrubs that grow in their natural habitat have very extensive, deep root systems. If transplanted they often must survive on small, unnatural root systems and may not do well.

If the soil that surrounds the plant becomes devoid of moisture, the plant will die. The best course of action is to allow the soil to dry and then water deeply. Do not water too frequently or the soil will remain soggy and wet. If the soil is too wet, it doesn't contain enough air and the root will rot.

Moisture Status

It is easy to determine the soil's moisture status by examining it. Soil that breaks easily and has shiny edges that glisten is either near or above its water holding capacity. Soil that will hold your handprint when squeezed has ample water. If the soil will not hold your handprint, it needs to be watered deeply. If soil is more than two inches in depth, it will never dry out enough to be dusty. Soils that contain as much as 6 percent moisture may not be able to sustain plant life because it is held tightly enough that the plant's roots cannot access the moisture.

Surface soil is the first to dry out. If dry weather continues, the dryness of the soil will progress in depth. If you grow plants that have shallow root systems, such as leafy vegetables or turf grasses, be sure to examine the entire root zone.

Dry Spells and Drought

Water shortages are critical to plants at pollination or when they are setting fruit. Most plants can survive a dry spell, even a lengthy one, if they have an adequate supply of water.

Remember, plants need more water in the hot, dry summer months. Temperatures are high and days are long. The temperature doesn't decrease as much at night, and this is hard on all plants.

If a drought continues for a prolonged period, water the soil deeply. If there is a water shortage, or water restrictions, give the plant two thirds of the required amount and hope the drought ends.

Recharging the Root Zone

When watering, give enough to recharge the entire root zone. The best way to determine that this has been accomplished is to examine the soil. Loamy, sand soil holds 1 inch of water per foot of depth. Clay holds approximately 2 inches and sand holds only 1/2 inch. This means that plants rooted in loam soil can do without water four times longer without water. However, remember that it will take four times more water to recharge the root zone.


When applying water, be sure to use a method that will allow even distribution of the water. Be sure it isn't given at a rate faster than the soil can absorb. In gardens, or where there is bare soil, soakers or flood type irrigation will prevent impact damage. However, a large amount of water will enter the soil near the equipment. An even distribution is almost impossible to obtain. Soil only takes on water vertically. To use flood type irrigation, the soil must be level. Flood type irrigation is fine to water one shrub or tree, but not a large area.

Sprinklers that oscillate or rotate are convenient and quite efficient. A covering of light mulch will prevent bare soil from impact damage. On lawns, turf prevents impact damage, as it forms a protective layer. However, even water distribution with these types of systems is hard to obtain, as the spray is affected by the wind.

Hoses that have a spray nozzle attached are also affected by the wind. These have a very fine spray that will not cause any impact damage.

Watering Preferences

If there is a water shortage, you will have to decide which of your plants need water the most. The most logical watering preferences is as follows:

  • Shrubs and trees with poor root systems.
  • Gardens
  • Lawns
  • Shrubs and trees with extensive and healthy root systems.


  • As stated earlier in the article, water deeply and less frequently.
  • Recharge the soil with a distribution that is as even as possible.
  • Water plants that are in a critical stage.
  • Use an irrigation system that will not cause impact damage, or use mulch to form a protective layer.

If you follow the watering guidelines in this article, your yard, garden and lawn will remain healthy. Even if it enters a dormant period, it will be easily revived.

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