Summer 2016 Landscape Update & Watering Guidelines

Conditions in the region were dry last fall, the winter lacked normal snowfall amounts, and now some areas of Massachusetts have a rainfall deficit in excess of 6 inches for 2016.  The heat that has now settled in has only exacerbated the challenges for landscape care.  Almost 30% of Massachusetts (including Middlesex county) is now classified as "Severe Drought". Many cities and towns are now under outdoor water restrictions. 

Watering efficiently is extremely important in periods of drought. Consider the following guidelines when watering your home landscape:  

General Tips for Watering Outdoor Plants  

During dry seasons, watering is necessary to maintain healthy plants. Water is more important for new plantings than for established ones.  

In trying to conserve water and to realize the greatest benefit from water used, it is wise to set up a regularly scheduled program.  

  • Do not try to water all planted areas at each watering.  

  • Section off your areas, and concentrate on these areas individually for maximum benefit.  

  • Saturate each area, and then allow to dry out before watering again.  

  • Plan to use mulch around all planted areas to reduce water loss.   

  • Overwatering can be more harmful to plants than underwatering. Roots need air as well as water. Do not keep soil saturated with water continuously.  

Watering Trees and Shrubs  

Established trees and shrubs do not require as much water as new plantings, but during July and August some watering may be necessary. Basic principles include:  

  • Watering with a hose and nozzle is not recommended. Merely syringing the plants and soil is of little value to the root system through which water is absorbed. Soaker hoses and slow release watering bags can be helpful tools in water application. 

  • An open hose placed at the base of a tree with the water flowing slowly will provide needed water to the root zone. If the water is allowed to trickle into the soil gradually, it will seep down and saturate the area around the roots. Since the composition of soils varies, the rate of absorption will vary, but the water pressure should be as high as possible without surface run-off.  

  • By saturating the soil around the plants, less frequent watering will be necessary. For established plantings, each plant or bed should be saturated approximately once every two weeks or less depending on the weather. New plantings will require more frequent watering than established plants. The same type of method should be exercised, but one to three times a week may be necessary for new plants. A ring of soil around newly planted trees and shrubs in the form of a saucer is recommended. This could be built from gravel or excess soil after planting. Fill the ring at each watering to allow gradual seepage into the soil. For the first month, water new plantings three times a week, then weekly for the rest of the season. Continue to monitor new plantings into the second and even third growing seasons. 

  • Each water application should last between one and four hours in a period of drought. Different soil types will absorb water differently. (Get to know your soil. Rub some soil in between your thumb and forefinger. If it feels gritty, it has a higher sand content and won't hold as much moisture as other soils. If it feels slippery, it has a higher clay content and is prone to compaction, but will hold more moisture than sandy soil. If it feels crumbly and soft, it has a higher amount of organic matter and will hold moisture well. Consider adding organic matter (compost) to sandy or clay soils.)  

Mulching can help to reduce water loss. The use of mulch on new or established plantings is an excellent method of conserving water. Beds which are exposed to the sun and drying winds without cover will dry out rapidly. Trying to keep these areas moist by watering is not adequate, and a great deal of water is wasted.  

Bear in mind, plants that are damaged by drought conditions may not show signs of distress right away; sometimes syptoms do not appear until the next growing season.

Watering Flower and Vegetable Gardens  

Annual and perennial gardens should be watered in the same way as trees and shrubs. A fine-textured mulch or soil conditioner such as peat moss should be used to help retain moisture. Flower and vegetable gardens may require more frequent watering. Again, merely sprinkling the beds lightly each day will not be adequate for efficient water use. Soaker hoses laid under a layer of mulch are excellent tools for proper water application. Saturate the areas once or twice a week during drought periods, and watch the plants closely. If wilting occurs, water should be applied more often; but under normal circumstances twice a week should be ample if a mulch is used. Less frequent, longer waterings will also encourage deeper root growth which will help plants withstand the inevitable moisture fluctuations that occur near the soil surface. 

Watering Lawns  

Frequent lawn watering often encourages shallow rooting and may predispose the lawn to increased disease and greater susceptibility to stress injury. Watering deeply and less frequently provides for improved turf growth and increased water conservation compared to light, frequent watering. When irrigation becomes necessary, sufficient water should be applied so that the soil is wetted to a depth of four to six inches. This amount of water will vary with soil texture, but approximately one inch of water should thoroughly wet most soils to a depth of four to six inches. Placing several empty cans (tuna or cat food cans work well) under the sprinkler will allow you to determine when an appropriate amount of water has been applied.  

You can irrigate your lawn at any time during the day or night. However, both day and night watering have their advantages and disadvantages. Midday watering can serve to cool the turf and reduce heat stress on hot summer days. However, if drainage is inadequate, pools of standing water can become very hot and result in turf death due to scalding. Also, midday watering is relatively inefficient due to substantial evaporation losses.  

A widely held belief is that night watering will incite or aggravate disease problems. One must consider, however, that the turf is usually wet during the night anyway even if irrigation is withheld because of dew formation. Recent research has suggested that the duration of leaf wetness has a greater impact on disease incidence than night watering per se. In that case, watering during early evening or late morning (just prior to or following dew formation) might result in increased disease by prolonging leaf wetness. Night irrigation helps to conserve water because of minimal evaporation at night. Unless disease is present and actively damaging the lawn, there is little reason to avoid night watering. Late afternoon or early morning watering may help to minimize evaporation without aggravating disease activity. 

Source: UMass Center for Agriculture, Food and the Environment