Water Conservation in the Landscape Bodie Pennisi, Extension landscape Specialist Landscape Best Management Practices Stages / Categories 1. Planning 2. Installation 3. Management BMP: Planning Stage Soil Testing Should be the first thing done. Will give a assessment and recommendation for meeting a target. Where is the Water? What is the irrigation source (well, surface, municipal)? Weather records- rainfall averages Observe other plants in the neighborhood (indicator plants) Structure/texture of the soil Drainage Right Plant in the Right Place Divide the Landscape into Three Water-use Zones High Water-use Zones (Oasis Zones) Moderate Water-use Zones (Transition Zones) Low Water-use Zones (Xeric Zones) 1
High Water-use Zones (Oasis Zones) Small high-impact or high visibility areas of the landscape where plants are provided their optimum water requirements at all time Entrance to the home or business Moderate Water-use Zones (Transition Zones) Plants are watered during establishment. Then, once established, they are watered only when they show signs of water stress. Azaleas, Dogwoods, Redbuds, Herbaceous Perennials Low Water-use Zones (Xeric Zones) Once established, plants receive no supplemental irrigation, except during periods of extreme drought Juniper Crape Myrtle Yaupon Holly Oaks Native Areas 10% of the landscape is irrigated regularly 30% of the landscape is irrigated on demand 60% of the landscape is not irrigated 80% of Plant Problems Result from the Inability of the Plant to Tolerate or Adapt to the Environment Stressed plants are generally more prone to insect and disease problems. More plants are killed in Georgia from too much water than from the lack of water! Photo credit: Rick Smith 2
Environmental Stress Too dry Too wet Fluctuations in soil moisture Too much sun Too much shade Cold injury Heat tolerance BMP - Installation Stage Avoid Soil Compaction Keep construction activities several feet from landscape plantings Possible Solutions to Poorly-drained Soils Decreases aeration/drainage/root growth Can result in fungal diseases Can result in plant decline and death Plant on raised beds Deep cultivation Install sub-surface drainage Select appropriate plants What Did the Soil Test Tell You? Soil Health is Essential At planting lime if ph is low (adds Ca and ph) Gypsum to existing plantings if needed (adds Ca; no change of ph) Till or disturb as large a volume as possible Soil Amendments Soil amendments (for the right reason) Annually add organic matter to annual and perennial beds to increase rootable soil volume Facilitates tilling and improves soil structure Use only decomposed organic material (right) as a soil amendment 3
Soil Amendments - How Much? Till/ incorporate 2.5 to 4 inches of organic amendment (compost) to a maximum depth of 8 to 12 inches. Be careful when planting around established plants! 80% of the roots of established trees and shrubs are within the top 12 inches of the soil surface. Fill dirt or topsoil added over the roots of established plants can smother their roots and cause stress. Did you know -- For every 1% increase in organic matter content, an acre of soil can hold as much as 16,500 gallons of water! Select Plants Adapted to the Site and the Stresses of the Environment: Drought tolerance is important, but also consider potential insect and disease problems, sunlight, and soil requirements. Myth: Native plants are more drought tolerant than introduced species Not all native plants are drought tolerant. For example, Virginia Sweetspire, Summersweet Clethra, Sweetbay Magnolia, and Inkberry are native to moist sites and are not drought tolerant. Established, healthy trees and shrubs can survive weeks without supplemental irrigation Select plants adapted to the site conditions and climate, regardless of their origin. 4
Plants with thick, fleshy roots and other water-storing root structures Examples: Daylilies Iris Red-Hot Poker Dahlias Gaura Mulch, mulch, mulch! A variety of mulch types are available depending on your personal preference including; shredded cypress, pine bark, shredded hardwood, pine straw, and many more. Maintain a 3-5 inch layer. Mulching Trees Mulching Trees Apply a 3-inch thick layer of mulch to at least an eight-foot diameter circle Apply a thinner 1 layer of mulch over the root ball if necessary, but keep it at least 10 from the trunk Mulch as large an area as possible to allow the tree roots to expand without competition from turf roots. Improper mulching If turfgrass grows up to the trunk, trees often perform poorly. Turf and weeds rob trees of moisture and nutrients and some produce chemicals that inhibit tree growth. Lawn mowing equipment damages trunk Improper mulching Never pile mulch in a volcano-like manner against the trunk. This can rot the trunk, cut off oxygen to roots, keep vital irrigation and rain water out, and can keep roots too wet in poorly drained soils. Stem girdling roots form from this on some trees. 5
Install Appropriate Irrigation Consider installing a micro-irrigation system Avoid using overhead sprinklers for shrub and flower beds (Approximately 65% of overhead irrigation can be wasted by evaporation, wind dispersal, and runoff) Low volume irrigation systems are sometimes exempt from irrigation restrictions! Don t Let Water Get Away! Permeable surfaces Infiltration Basins Rain Gardens Water Collection An area in a man-made landscape that captures a shallow amount of water and holds it for a short time period Runoff water is captured and infiltrated into the soil in an indented area where plants and soils utilize and filter the water Low maintenance, low water use Reduced flooding and stream bed destruction downstream Wildlife habitat Healthy Trees: During establishment BMP- Management Stage Irrigate - 2 3 times weekly until established - 2 gallons per inch trunk caliper on root ball Irrigating daily makes for healthier trees, but 2-3 times per week keep plants alive. 6
Irrigation: is it volume or frequency? Frequency of irrigation based on tree size It s frequency! Experiment done on 4- inch hardened-off B&B trees where 1.5, 3, or 5 gallons of water were applied per inch trunk caliper. Size of nursery stock < 2 inch caliper 2 4 inch caliper Irrigation schedule for vigor Daily: 2 weeks Every other day: 2 months Weekly: until established Daily: 1 month Every other day: 3 months Weekly: until established Irrigation schedule for survival Twice weekly for 2-3 months Twice weekly for 3 4 months Results show that volume did not matter but frequency did. > 4 inch caliper Daily: 6 weeks Every other day: 5 months Weekly: until established Twice weekly for 4 5 months Months of irrigation to provide based on climate and tree size at planting Herbaceous Plants and Shrubs USDA Hardiness Zone Max. trunk diameter at planting 5 6 7 8 9 10 1 inch 12 mo 10 mo 7 mo 5 mo 3 mo 3 mo Deep, infrequent watering Light, frequent watering 2 24 20 15 10 6 6 3 36 30 23 16 9 9 4 48 39 30 21 12 12 Use Your Eyes! Watch for moisture stress symptoms before deciding when to irrigate. An abnormal gray-green color or obvious wilting are good indicators that a plant needs moisture. Confirm this by digging a small hole to see if the soil is wet, moist, or dry. Watering plants only when they require it will result in a deep, strong root system that preconditions the plant to tolerate dry periods. Specific Practices for Bedding Plants, Shrubs & Trees Irrigate trees and shrubs ONLY after they start to wilt Watch Indicator Plants for signs of wilting: Azalea Gardenia Hydrangea Dogwood Hibiscus Impatiens Japanese maple Trumpet tree (Datura) 7
Know your fertilizer Slow-release type fertilizers and/or compost release nutrients over an extended period of time resulting in more uniform growth rates and more water-efficient plants. Excess nitrogen causes rapid growth and increases a plant s demand for water. Keep the mulch coming. Maintain an average mulch depth of 3 to 5 inches. This may require you to add 1to 3 inches of additional mulch each year. Management Practices that Lead to Drought Stress Symptoms Severe Pruning (A.K.A Crepe Murder) If it s done, it must be OK 8
GUY WIRE DAMAGE Staking straps left too long Irrigation System: Spray heads out of plumb/exposed degraded spray performance; flood/dry, flood/dry cycle leads to steady soil structure degrade DRASTIC MEASURES! So when the drought is severe and water restrictions are in full force: What can be done? Only irrigate plants upon severe wilting Remove weak or less desirable plants DRASTIC MEASURES! Apply chemical wetting agents or incorporate organic matter to areas of the landscape where the soil has become hydrophobic (water runs off rather than is absorbed by soil) Long-Term Effects of Drought Signs of Residual Plant Stress Water sprouts/uneven growth Pests that move in on stressed plants Borers! Azalea leafminer Botryosphaeria and Hypoxylon cankers Armillaria and some other root rots 9
We support: Before considering the use of terms like "drought tolerant", it should be recognized that once established and with proper cultural practices (such as amending the soil and mulching); most plant material will be "drought tolerant" and survive most droughts. The most common reasons for planting failures are improper plant location (putting a plant with high light needs in shade) and improper soil preparation. Summary We support: A holistic approach involving Best Management Practices (BMPs) to obtain maximum landscape sustainability and water efficiency. One of the many principles in BMPs is putting the "right plant in the right place". This requires selecting proper plants to install in specific landscape microenvironments, such as cool and moist northern exposures versus hot and dry southern exposures. 10