Knock Out Roses

NOW is the best time to plant your new landscape.  Springtime planting may be good in some parts of the country, but the fall season is actually better for planting and root establishment.   According to Texas Nurserymen, “Plant roots grow anytime the soil temperature is about 40° F or slightly higher, and this occurs nearly all winter long in most of the state.  The root systems of the fall-planted specimens thrive and become well-established making it possible for the plant to take advantage of the full surge of spring growth.*”  Trans-planting shock is also minimized.

If you are making significant changes to your landscape, don’t forget about your irrigation system.  Most systems are designed/installed to accommodate a specific landscape.  The high-pressure stream from a rotor head will wreak havoc on a flowerbed.  Before you alter the footprint of the original landscape, consult with your irrigator to determine the best plan to modify the coverage of your sprinkler system.

Be sure to plan ahead and provide all your new plants with the appropriate delivery of irrigation.

*David Rodriguez
Texas Cooperative Extension
The Texas A&M University System Extension Horticulturist &
Bexar County Master Gardener Coordinator
3355 Cherry Ridge, Ste. #212
San Antonio, TX 78230-4818

Follow these steps to re-activate your irrigation system:

1. If applicable, open both manual shut-off valves on your PVB (Pressure Vacuum Breaker) and close the “test-cocks”.
2. Open the system main water valve slowly to allow pipes to fill with water gradually. If these valves are opened too quickly, sprinkler main lines are subjected to high surge pressures, uncontrolled flow and water hammer.
3. Verify the proper operation of each zone valve by manually activating it from the controller.
4. Walk through each station on the controller, checking for proper operation of the zone. Check for proper operating pressure (low pressure indicates a line break or missing sprinkler), proper rotation and adjustment of sprinkler heads, and adequate coverage. Check and clean filters on poorly performing sprinklers. Adjust heads to grade as necessary.
5. Reprogram the controller for automatic watering. Replace the controller back-up battery if necessary.
6. Uncover and/or clean the system rain sensor, if applicable.

If you discover any broken heads, non-activating zone valves or broken pipes, give me a call.  I’ll be glad to help.

Pressure Vacuum Breaker

Now that we are experiencing lower temperatures and (finally) some rain, it would be a good idea to winterize your irrigation system before the next hard-freeze.  The following steps will help protect your sprinkler system and backflow device from damage due to freezing temperatures:

1. Turn “OFF” the manual shut-off valve (usually located near the meter) by rotating the handle 90º.

2. Briefly, cycle through each zone (from the controller) to relieve pressure in the main-line and zone pipes.  The residual water in the pipes  will then be below ground and not under pressure.  Leave the controller in the “OFF” position.

3. If you have a Pressure Vacuum Breaker (PVB), open the test cocks with a straight screw driver and rotate both valve handles  45º to prevent freezing/locking in the open or closed position.  Wrap/Cover the PVB (and any exposed pipes) to further prevent freezing.

In the BCS area, we would have to experience many consecutive days of freezing temperatures to damage below ground pipes.  Your main concern should be any part of your sprinkler system that is above ground level and/or your PVB.  If you have any questions, let me know.

Infrequent and deep watering is preferred to frequent and shallow watering because the roots will only grow as deeply as its most frequently available water supply. Deeply rooted grass has a larger “soil-water bank” to draw moisture from and this will help the grass survive drought and hot weather that rapidly dries out the upper soil layer.

The Irrigation Technology Center at TAMU reports that the current water requirement for St. Augustine grass is 0.5 inches per week. Fixed spray heads can achieve this rate of application rather quickly as they broadcast a large amount of water over a relatively small area. Rotor spray heads take longer to apply this amount as they cover large areas with a single, rotating jet of water. A relatively accurate rule-of-thumb is to irrigate rotor zones 3 times as long as fixed spray zones. Fixed spray heads apply between 1.5-1.7 inches of water per hour. In this case, 0.5 inches can be achieved in about 20 minutes. Most rotor sprinkler heads apply approximately 0.5 inches per hour. In order to achieve the required amount of water, rotor zones need to water for about an hour. Unfortunately, our soils in this area will not absorb this amount of water quick enough to accommodate that much water in one application. Much is lost to evaporation or run-off. In the B/CS area, the most beneficial way to achieve the required amount is to divide the total watering times over 2 or 3 days and to irrigate in the early morning hours between 5:00&10:00 AM. This minimizes losses due to wind, run-off and evaporation. In an effort to conserve water, College Station requests that residents water a maximum of twice per week. See the following link for their recommendations:

http://199.5.231.99/modules/ShowDocument.aspx?documentid=4614

During the hotter, summer months, evaporation will be more significant. Look for footprints: if you leave footprints on the grass after walking on it, it’s not getting enough water.

Please note: This irrigation performance data is based on properly designed/installed irrigation systems. Not all systems meet these criteria. I also strongly recommend the installation of a rain sensor. This will eliminate watering when you don’t need to… thanks to the rain.

If you have any questions, let me know!