Watering Outdoor Plants
The signs of a well-cared for yard are a green, weed-free lawn, healthy trees and healthy shrubs. They are an investment in the value of your property and should be protected.
The question of how much to water and how often has no single answer. It depends on weather conditions, soil composition and the plants themselves.
Consider:
1. Weather: On a hot, sunny day in midsummer, the average lawn uses 125 gallons of water per 1,000 square feet. The same lawn on a cool, cloudy day uses as little as 10 gallons of water. Mature trees can use up to 15 gallons of water per hour on a hot day. Any plant exposed to hot sun, low humidity and strong winds will evaporate large amounts of water that must be replaced from the soil or it will die. Grass is particularly susceptible since 85% of its bulk is water.
2. The Plants: A good drenching once or twice a week is better for your lawn than daily light sprinklings. Deep watering produces strong, deep root systems that can safely withstand drought. This requires a long, thorough soaking of the soil, ideally to a depth of about 1 foot but at least 6 to 8 inches. A steady stream of water will run off. An even, intermittent sprinkling is best for deep penetration.
3. Soil Type: Coarse, sandy soil has large air spaces that quickly fill with water but also lose water quickly to the subsoil requiring shorter, more frequent watering. Heavier clay or silt soil has numerous smaller spaces that absorb water slowly but hold more water than sandy soil. Clay soil should be watered slowly but less frequently. Loam-type soil falls in between, holding water longer than sandy soil but not as long as heavy clay soils.
Let the soil dry between watering. Roots will grow deeper, looking for water below the surface as soil dries. Roots need to absorb small amounts of oxygen from air spaces in dry soil and are warmed by the drying soil. This also discourages weeds, which are often shallow-rooted.
Light watering produces shallow roots in the upper few inches of soil that are subject to rapid drying. In addition, many weeds have shallow roots that thrive on moisture near the surface. Too-frequent watering produces wet areas susceptible to lawn diseases, insects and drown root damage.
When to Water
Most lawns need 1 to 2 inches of water per week depending on water and soil conditions. Nature supplies water as rain or dew but sometimes doesn't supply what's needed. In dry areas, a regular watering of at least once a week or more is important (skipping days when it has rained heavily). During the more moderate spring and fall or in cooler, wetter regions, look for signs that watering is needed. A slowing of the growth rate, changes in color or loss of resilience (footprints showing in the grass) are signs water is needed. Check the soil 2 to 6 inches below the surface. If the soil is dry and crumbles easily, it's time to water.
Time of Day
- Early morning is best because water pressure is high, it's still cool so evaporation is low and seepage into the soil is best before the sun bakes the ground hard.
- Late afternoon is the next best time, but be sure that it's early enough for the leaves to dry before nightfall.
- Night watering is not recommended because the lawn and other plants stay wet for a longer time, promoting lawn diseases.
- Midday watering usually doesn't hurt anything. In the heat of the day, a great deal of water is lost to evaporation before it soaks into the soil.
How Much to Water
If nature hasn't supplied water as rain, apply approximately 1 inch of water, (a general rule of thumb). This will give deep penetration of the soil to a depth of 6 to 8 inches. One inch of water or rain is equivalent to 623 gallons per 1,000 square feet. Water should be applied no faster than the soil is able to absorb it. If water begins to run off before 1 inch is applied, stop sprinkling until it's absorbed and then resume.
How long will applying 1 inch of water take? This depends on the size of the hose, pressure and type of sprinkler being used. There are several methods for determining how much you’re applying.
1. Do the Math: Find the gallons per minute (GPM) flow rate of the sprinkler being used from the package of the manufacturer. Multiply the square footage to be watered by .62 gallons or 1 inch of water per square foot. Example: 1,000 square feet x .62 gallons = 620 gallons. This tells you how many gallons of water you need to apply to the lawn. Divide that number by the GPM of your sprinkler, and you can figure how many minutes to water.
2. Collect the Water: Place a cup or glass in the middle of the area covered by your sprinkler, turn water on and watch the time. Measure water in the cup until 1 inch is collected. This is the time you need to sprinkle. The best accuracy is obtained if you use several containers at different places in the sprinkler’s coverage pattern and average the results.
3. Buy a Flow Timer: Often called water timers, these units actually measure water flow. They are calibrated in 100 gallons and can be set from 100 to 1,500 gallons to give you the water necessary for the square footage covered by the sprinkler. Use the formula in Step 1 to calculate the gallons needed.
4. Test the Soil: Test the soil 6 inches or more below the surface to make sure it's dry. Turn on your sprinkler, and periodically test the soil 6 inches down until the water has penetrated to that depth. Keep track of how long it took, and use that as the time you need to water.
Watering Equipment
You'll need the proper equipment to water your lawn and garden:
- A quality, multiple-ply, reinforced garden hose.
- A rain gauge to know when your lawn or garden needs additional water.
- A plastic or galvanized watering can with a detachable rose sprinkler head.
- A water or spray wand that attaches to your garden hose for watering flowers and container plants.
- Pulsating or oscillating sprinklers for specialized watering.
Watering Tips
Wise water use is one sign of a good gardener. Follow these tips to keep your lawn and garden adequately watered:
- When choosing plants for the landscape, look at the plant tag for water requirements. Group plants with similar water needs to maximize water resources.
- Be observant. Watch for signs of plants in need of water. Take extra care to water newly planted shrubs, trees and lawns. Even plants that are considered drought-tolerant need steady watering for the first 1-2 years in order to get established.
- Retain soil moisture by using compost, shredded leaves or mulch around vegetables, annuals and shrubs. Keep weeds pulled from planting beds. They compete for moisture and nutrients.
- To minimize evaporation and fungal diseases, water only in the early morning. However, if you see that the lawn or garden is becoming stressed or endangered from lack of water, go ahead and water without delay. Avoid watering with sprinklers on windy days.
- Water lawns irregularly, rather than on a strict weekly schedule. This replicates natural weather patterns and helps make lawns more drought-tolerant.
- For best growth, water trees and large shrubs at the drip line.
- For smaller plants, use soaker hoses and drip irrigation to deliver water directly to the base of the plant where it's needed.
- To promote root growth, water deeply and allow soil to dry slightly between waterings. A strong root system creates hardier turfgrass. Light, shallow sprinklings evaporate before water is able to saturate the soil where it's needed.
- When you can’t water every day, use pots and saucers to collect excess water. This will eventually be drawn up into the container soil, keeping it from drying out so quickly. You can also group containers so they help shade each other.
- Mow at the recommended height for your type of turfgrass. Cutting grass too close stresses the plant. Letting grass grow too tall increases the chance of disease.
- Remove lawn thatch and aerate when needed to increase the soil's water absorption.
- Consider hydroponic gardening. Also known as hydrogardening, this is an indoor growing system where plant roots are supported by soil-less blends such as peat or coco coir. Nutrients are added to the water to promote plant growth. Although water is the growing medium, water use is considerably less that plants grown in soil.
- Consider xeriscaping, which incorporates wise water use into the landscape to eliminate the need for irrigation without sacrificing beauty and color.
- If you have an underground sprinkler system, keep it adjusted and well-maintained.
- Locate and remedy any spots that are prone to erosion. Runoff water does no one any good.
- Save on water bills by collecting rainwater from downspouts and storing it in rain barrels. You’ll be surprised how quickly the barrels fill up after a rainstorm. Check to make sure there are no ordinances against collecting rainwater in your community.
- Water expands as it freezes. If you live in a freeze area, at the end of the season you should drain hoses, water timers and sprinklers before the first frost. Store them where they won't freeze.
Be sure to observe any water-use ordinances or restrictions for your area.