Watering Landscape Plants AGSC 361 Landscape Design, Construction, and Maintenance Instructional Materials Service Texas A&M University

Today We Will…  Discuss the functions of water in plant growth and development.  Explain the effects watering has on landscape plants.  Describe how to determine when landscape plants need watering.  Discuss methods of watering landscape plants.

Today We Will…  Explain how to determine the quantity of water to apply to landscape plants.  Discuss the importance of water quality considerations.  Explain how to determine the time and frequency for watering landscape plants.  Describe effective and efficient watering practices used in watering landscape plants.

Functions of Water in Plant Growth and Development  Provides essential nutrients.  Major component of plant cell.  Solvent and medium for chemical reactions and processes  Maintains turgidity.  Medium for transporting nutrients and food.  Component of photosynthesis.  Assists in the movement of plant parts  Maintains stable temperature within plant.

Water and Turgidity  Water is important for keeping plants and their cells turgid. Turgidity is a plant state in which the plant is rigid and inflated with water. Turgidity is a plant state in which the plant is rigid and inflated with water.  Plants may appear wilted due to a lack of turgor pressure. Turgor pressure is the pressure inside a cell due to water uptake. Turgor pressure is the pressure inside a cell due to water uptake.

Water and Turgidity

Water and Temperature Stability  Water serves as a buffer within the plant against sudden changes in the exterior environment. In cold temperatures, water maintains plant energy and uses it to moderate the temperature of the plant. In cold temperatures, water maintains plant energy and uses it to moderate the temperature of the plant. In warm temperatures, water releases heat to cool the plant. In warm temperatures, water releases heat to cool the plant.

Water Functioning in Soil  As they absorb water from the soil, plant roots also absorb minerals that have been dissolved in the soil water.  Plants lose a great deal of water due to transpiration and replace this lost water with moisture from the soil. Transpiration - plant releases water from its leaf surfaces in the form of water vapor Transpiration - plant releases water from its leaf surfaces in the form of water vapor

Water Functioning in Soil  Leaching occurs when nutrients are washed past the root region and become unavailable to plants.  Water applied to the soil helps leach out excessive levels of minerals in the soil near the plant’s roots.

Water and Landscape Plants  Landscape plants require adequate water to survive.  The amount of water a plant receives affects its growth and development.  Both under-watering and over-watering impact plant growth and development.  Determine whether plants need to be watered by observing them for signals or by checking the soil for moisture.

Effects of Under-Watering  Reduced growth rate.  Reduced rate of photosynthesis.  Wilting due to decreased turgor pressure when plant transpires faster than roots can supply lost water.  Eventual death due to lack of water and permanent wilting.

Effects of Over-Watering  Taller growth with less compactness.  Shallow root system.  Nutrient deficiencies due to leaching and shallow root system.  Plant roots may “drown”

Signals that Turfgrass Needs Water  Wilting in which leaves bend or roll up.  Overall dull, grayish appearance.  Leaves appear dull with a bluish-green to purplish cast.  Grass lies flat after being walked on.  Intrusion of weeds.

Signals that Trees, Shrubs, and Groundcovers Need Water  Discoloration in which leaves go from glossy, bright-green to dull, gray-green.  Wilting.  Premature leaf, bud, and flower drop.  Death of young leaves.

Watering Needs of Container Plants & Transplants  A high potential for drought stress occurs in container plants because moisture from the surrounding soil does not move into the container soil mix and root zone quick enough to prevent drought stress.  Frequent watering is necessary until the root systems of transplanted plants spread and develop into the soil of the new location.

Checking Soil For Moisture  Cane or Stick Insertion Insert a cane or stick into the soil around the root system. Insert a cane or stick into the soil around the root system. If it has no moisture or soil clinging to it when removed, water is needed. If it has no moisture or soil clinging to it when removed, water is needed. Moisture or soil clinging to it indicates adequate moisture. Moisture or soil clinging to it indicates adequate moisture.  Observing the Soil Soil appearing light in color and dry to the touch indicates a need for watering.

Checking Soil for Moisture  Feeling the Soil Roll or squeeze a small bit of soil into a ball. Roll or squeeze a small bit of soil into a ball. A soil ball that crumbles when rubbed has proper moisture. A soil ball that crumbles when rubbed has proper moisture. If the soil ball does not crumble when rubbed, it is too wet. If the soil ball does not crumble when rubbed, it is too wet. Water is needed if soil will not form into a ball. Water is needed if soil will not form into a ball. Sandy soils crumble even when wet. Sandy soils crumble even when wet. Photo Courtesy of USDA Natural Resources Conservation Service

Methods of Watering Landscape Plants  Sprinkler Irrigation  Drip Irrigation  Surface Irrigation  Manual Irrigation

Sprinkler Irrigation  Most commonly used method of irrigation.  Effective and efficient method of evenly distributing water over a lawn area.  Applies large volumes of water in a short time.  Requires minimal maintenance.  Includes hose-end sprinklers and automatic underground pop-up sprinkler systems.

Types of Hose-End Sprinkler Systems  Oscillating Sprinklers  Spray Type Sprinklers  Impact Sprinklers

Oscillating Sprinklers  Provide an even supply of water back and forth across an area.  Maintain an even watering pattern throughout lawn area.  Should be moved frequently and evenly throughout the area.  Should overlap about half of each pattern when moved.

Spray Type Sprinklers  Distribute water to an area either with a fixed spray or rotary spray.  Provide a constant, uniform supply of water to an area.

Impact Type Sprinklers  Shoot a fine spray of water across an area.  Impact of water passing through the sprinkler nozzle changes the direction of the stream in short movements around the sprinkler.  Those on risers of about 2 to 3 feet sprinkle water above shrubs, providing a more equal distribution of water. Photo Courtesy of USDA Natural Resources Conservation Service

Selecting a Hose-End Sprinkler  Choose one that sprays large water drops, close to the ground.  Avoid sprinklers that produce fine streams of water high into the air.

Automatic Underground Pop-Up Sprinkler Systems  Consists of the following components: Underground distribution lines. Underground distribution lines. Electrically controlled valves. Electrically controlled valves. Electric program controller. Electric program controller. Pop-up sprinkler heads. Pop-up sprinkler heads.

Automatic Underground Pop-Up Sprinkler Systems  Advantages More water efficient than hose-end sprinklers. More water efficient than hose-end sprinklers. Sprays water near the ground and closer to the roots of plants. Sprays water near the ground and closer to the roots of plants. Allows for dividing areas into zones that can be watered separately, according to specific needs. Allows for dividing areas into zones that can be watered separately, according to specific needs.  Disadvantages Expensive to install. Nozzles may require cleaning if clogged. Heads and nozzles may have be adjusted to ensure walks and drives aren’t watered and large drops rather than a fine spray is emitted.

Drip Irrigation Systems  Involves the following components: Supply tubes Supply tubes Thin connecting tubes Thin connecting tubes Emitters Emitters Photo Courtesy of USDA Natural Resources Conservation Service

Advantages of Drip Irrigation Systems  Efficient  Economical  Improved Plant Health

Disadvantages of Drip Irrigation Systems  High cost of materials and instillation.  Emitters may occasionally become clogged.

Guidelines for Use of Drip Irrigation Systems  Operate system for at least three hours to achieve thorough soaking.  Bury supply tubes and thin tubing, or cover them with mulch.

Surface Irrigation  Involves flooding or allowing water to cover an area.  Commonly used in landscape for watering flowerbeds.  Also used in landscape for close plantings of trees or shrubs.

Surface Irrigation  Advantages Provides good, uniform wetting of the soil in the irrigated area. Provides good, uniform wetting of the soil in the irrigated area.  Disadvantages Uses a great deal of water. Requires a level surface, or runoff becomes a problem.

Guidelines for Surface Irrigation  Construct small berm around area to be watered.  The berm creates a small basin to retain water and to prevent surface runoff.  Allow water to cover the soil surface to a depth of 1 to 2 inches. Berm

Manual Irrigation  Involves watering landscape plants by hand.  Supplies water to plants by means of a hose or bucket.

Manual Irrigation  Advantages Allows each plant to be personally monitored by the irrigator. Allows each plant to be personally monitored by the irrigator.  Disadvantages Requires a great deal of time. Requires a lot of labor. Requires a lot of water.

Using a Hose for Manual Irrigation  Make sure hose reaches all plants to be watered.  Attach a water breaker to end of the hose.

Using a Bucket for Manual Irrigation  Apply water slowly.  Do not pour all water at once.  Apply water close to the soil surface.

General Guidelines for Manual Irrigation  Fill the basin surrounding the base of the plant.  Allow water to infiltrate down into the soil in the plant’s root zone.  Do not allow excessive water runoff.  If no basin exists, apply water away from the trunk or stem to the canopy drip-line. Drip-Line

Factors to Consider in Selecting An Effective Irrigation Method  Size and topography of area  Type of plants  Labor requirements (time and cost)  Uniformity of application  Quality, quantity, and availability of water  Cost of installation  Life expectancy of system  Economics of operation

Determining Quantity & Frequency of Watering for Landscape Plants  Watering needs differ among landscape plants.  Factors to consider in determining how much water to apply to plants include: Plant Species Plant Species Plant Size Plant Size Plant Age Plant Age Stage of Plant Development Stage of Plant Development Soil Texture Soil Texture Slope of Land Slope of Land Environmental Conditions Environmental Conditions

Guidelines for Determining Quantity of Water to Apply  Apply enough water to thoroughly soak the soil surrounding the plants’ roots.  Apply water at a slow enough rate to prevent runoff.  Apply water regularly to newly planted landscape plants.

Guidelines for Determining Quantity of Water to Apply  Satisfy the water requirements of established plants.  Avoid applying too much water.  Consider water received in the form of rainfall.  Consider the placement of plants.

Determining the Effectiveness of Landscape Watering 1. Water an area for 15 minutes. 2. Dig to find the depth of moisture penetration. 3. Calculate the time needed to thoroughly soak plants based on the depth of moisture penetration.  Thoroughly wetting the root zone of an established large shrub or small tree may require 6 to 12 hours.

Determining Water Quantity Received by Lawn Area 1. Set several wide-topped, flat-bottomed cans with straight sides in a straight line out from sprinkler. 2. Check the water level in the cans at 15- minute intervals. 3. Adjust the sprinkler’s rate of application to about ½ to 1 inch per hour.

Determining Water Quantity Received by Lawn Area

Time for Watering Landscape Plants  Water during the early morning hours. Calm winds and a cooler temperature reduce water lost to evaporation and ensure a uniform watering pattern. Calm winds and a cooler temperature reduce water lost to evaporation and ensure a uniform watering pattern. Discourages development of disease-causing pathogens because foliage dries in a short time. Discourages development of disease-causing pathogens because foliage dries in a short time.

Tips for Effective and Efficient Watering  Water plants only when they need it and apply only enough to satisfy their needs.  Water plants thoroughly to reduce the amount of water and frequency of watering.  Mulch landscape plants to keep soil cool and to reduce water lost to evaporation.  Add organic matter to increase drainage in clay soils and to retain moisture in sandy soils.

Tips for Effective and Efficient Watering  Avoid watering weeded or unplanted areas.  Taper off watering during late summer and early autumn to encourage plants to harden and become tolerant to cold winter conditions.  Water plants periodically during the winter to supply water to plant roots as they continue to grow.

Things to Remember About Effective and Efficient Watering  The greatest waste of water is due to applying too much, too often.  Be observant in hot and dry summer weather when plants never absorb and use much of the water applied. As much as 50% of water is wasted through runoff and evaporation. As much as 50% of water is wasted through runoff and evaporation.

Water Quality Considerations  Use irrigation water that is free of suspended matter or particles.  Avoid using water with high salinity level  Chlorine and fluoride added to city water for health reasons usually isn’t present in high enough levels to affect landscape plants.

Water Quality Considerations  Water quality varies from one location to another.  In some cases, mineral content is so high that it affects plant growth.  Have water tested if problems occur.

ALL RIGHTS RESERVED Reproduction or redistribution of all, or part, of this presentation without written permission is prohibited. Instructional Materials Service Texas A&M University 2588 TAMUS College Station, Texas