Cashman Nursery - Bozeman, MT Growing for You Since 1898

Ten Watering Hints from the Professionals

By Jan Cashman 7/8/12

We don’t know what the rest of the summer will bring, but so far it’s been hot and very dry.  Humidity has been low and the trees, shrubs, flowers, and vegetables in our yards and gardens can easily become stressed.  Here are a few hints from those in the know…

  1. Water deeply and less often.  This was the most commonly mentioned hint by those I polled.  Whether it’s grass, trees, shrubs, or flowers, deep watering encourages deep rooting.  Just wetting the soil’s surface won’t do that; the roots will stay shallow.  Large trees will especially benefit by a trickling hose under them until the root system is saturated.
  2. Water in the cool of the morning, not the heat of the day when there is less evaporation.  This will waste less water.
  3. Water the soil, not the leaves of your plants.  Water hitting the leaves of your plants, whether  lettuce in your vegetable garden, or roses or quaking aspen can encourage fungus (leaf spot) diseases.
  4. Establishing new plants, whether sod, flowers, vegetables, shrubs or trees, takes more frequent and diligent watering than your established plants do.  These new plants are not rooted in well so their new root systems will dry out quickly.  The sprinkler system for your lawn is not enough for newly planted trees and shrubs.
  5. Group plants with like water requirements together for efficient watering.  Consider native plants that require less water.  Many beautiful landscape plants are drought tolerant, once established.
  6. A thick (up to 3”) mulch, such as soil pep (ground up bark), holds moisture in the soil and decreases weeds.  Mulches work especially well in perennial flower beds.
  7. Just because you have a drip or sprinkler system, doesn’t mean you can forget about it.  Drip systems can plug up; they can be set wrong.  Dana Durham, owner, Lawn Rain Sprinklers, recommends one or more 5 gallon per hour emitters for trees and 2 gallon per hour for shrubs, running twice a week on established plants.  Bubblers are recommended over traditional drip tubes for trees and shrubs—they are less likely to plug.   Dana is using a new, popular product called ‘Netafim’ to water perennial and annual flowers with emitters inside a pipe every 6” or 12” in a grid system.  The pipes can be covered with mulch to hide them.   Natafim stations for flowers are separate from the tree and shrub stations, coming on more often—sometimes twice a day during this hot weather.

    Reset your lawn sprinkler system to come on less often (possibly every other day during hot July weather, twice a week when the weather is cooler) but with a longer duration for each set.  (Newly laid sod needs to be watered more often.)

    You can check the amount of water your system puts out by placing straight-sided cans around under the sprinklers.   Don Mathre, former MSU Professor and Garden Club member, says that the old idea that plants need 1” of moisture per week does not hold true during dry and hot weather in mid-summer.  Reset your system and water more during these times.  Possibly as much as 2” per week or more will be needed depending on your soil type and where you live.  (Belgrade’s soils are rocky and drain quickly, so plants there need more water than those of us with heavy clay soil.)

  8. Stick your finger down a few inches into the soil to test its moisture.  And watch for wilting plants.  Close personal observation of your plants is the best.
  9. As summer progresses, decrease watering of trees and shrubs to encourage them to ‘harden off’ or go dormant.  This may mean cutting back on your sprinkler system settings, where trees and shrubs are planted, come August.   By then, the days are shorter and the nights cooler so less water is needed to keep your grass green.
  10. Remember, overwatering can be just as detrimental to plants as underwatering.  In low spots, with a sprinkler system, or where heavy clay soils are present, plants can drown.  Symptoms of overwatering are a lot like those of underwatering—yellow leaves, brown edges on leaves, wilting.   If the area is squishy wet when you walk on it, or if you have landscape fabric with mulch around your plants, check for overly wet ground and make corrections.

Enjoy your summer but, for the health of your landscape plants and lawn, be aware of their water requirements as the summer goes on.