In the middle of winter why should we give our sprinkler system a thought? Months will elapse before the system is brought back to life. Landscaping ideas are often “hatched” during the winter doldrums and how you are going to water the landscape should be your first consideration. Seed catalogues have already arrived in the mail, as well as agreements for annual landscape care. It really is time to think about your existing landscape, new landscape and sprinklers. At the risk of being macabre, inadequate water management is the primary reason for landscape demise.
Everyone is familiar with sprinkler systems that spray water on the lawn. A well operating sprinkler system yields a uniformly green lawn. If part of the lawn goes off color we know something needs to be addressed. What about drip irrigation? Admittedly, not everyone has a drip component to their sprinklers, but with the advent of more planting beds and water conservation, these systems are now common.
The purpose of drip is to apply water to plants outside of the lawn area, perhaps in a garden, mulched bed, or a raised berm area. Drip irrigation tubes are positioned adjacent to the new plants such that the roots are efficiently watered. The tubes are held firmly in place with a wire anchor.
Drip irrigation can be concealed in the landscape; it’s easily modified and conserves water. Because it is out of sight, it’s rarely modified and over time does not supply enough water to a growing landscape. If your drip irrigation system is five years old or order – please read on!
At landscape installation typically there are two emitter lines or “spaghetti” tubes assigned to each shrub or small tree. Larger trees may have three or four of these tubes. The tubes are placed directly over the root ball of the new plant. Usually the system is set to run for an hour and yield one to four gallons per tube per cycle. The idea here is to water the plants just enough for them to get situated in their new landscape and begin to flourish.
In order for plants to grow and flourish, the roots must grow out of the root ball exploring the native landscape soil for water and nutrients. The rub is the roots must grow past where the drip system tubes were originally placed. How do we compensate for the larger growing plants?
Shrubs
For small shrubs, perhaps not much needs to be done, except to make sure the drip system operates and ensure the tubes don’t get buried in the soil. If shrub foliage scorches in the summer (sign of water stress) more water is needed. More water may be delivered by lengthening the time the system runs, changing the emitters from two to four gallons per hour or adding an additional tube.
Trees
Trees will most always grow larger than shrubs and with higher water demands. Tree roots grow rapidly expanding past the original root ball. Expect tree roots to grow six to twelve inches per year. For the first year or two of the tree’s life the original drip system should be adequate. However, after the initial time period, periodic drip irrigation system modifications are likely needed.
Drip Tube Placement
Each year or so, move the drip lines six inches out further from the tree trunk. The final placement of the drip lines should be 36 to 48 inches from the tree trunk.
Number of Drip Tubes
Most installations begin with two drip tubes for shrubs and three for trees. A six foot tall tree should have at least three drip tubes. Trees taller than six foot should have four drip tubes.
How much water
Emitters are measured by how many gallons per hour they distribute. Common sized emitters on new installations are two gallons per hour. However as your tree grows, consider changing those to four gallons per hour.
Trees over Twenty Feet Tall
We are finding trees taller than twenty feet may not get enough water relying on drip irrigation.
The tree’s roots may grow from the bed area out into the lawn. This is the best case scenario and the drip system may become unnecessary, but what if the drip system is all the tree has to rely on?
Drip systems may be retrofitted with micro-spray irrigation heads. Micro-sprays will wet a larger surface area and may provide enough water.
Trees may be watered manually with sprinklers or soaker hoses can be placed underneath the tree canopy and connected to water spigot.
In Summary
Water management around landscape plants is not a one size fits all scenario. Soils and water requirements by individual species greatly affect the design of the sprinkler system. Once the snow clears and you prepare for sprinkler activation, it’s a good idea to call and have someone come out to advise you of what your specific plants’ water needs are. You may need sprinkler system repairs and/or you may be in need of supplemental watering services.
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