Don’t Water When it’s Already Wet

Don’t Water When it’s Already Wet

It amazes me that even under flood conditions, people still water their lawns.

I’m sure you’ve seen it too – we get enough rain to cause some areas to flood and yet you see irrigation systems going full blast.

Lawn irrigation spray head running
Lawn irrigation should be applied on an as needed basis. Credit: Larry Williams

We should water our lawns, landscapes and gardens on an as-needed basis. The way that some people water their lawns is as logical as saying that a pet dog needs a drink of water at 4 p.m. everyday. This is not true. When watering, we are simply replacing water that is lost. This is true when we drink water ourselves, when we provide water for a pet dog, or when we provide water for our lawns, landscapes and gardens.

An irrigation system is a great tool when used to supplement rainfall. Irrigating too much not only wastes water but it also is the cause for many lawn problems such as shallow, weak root systems, leaching of fertilizer and numerous lawn diseases. Cutting the irrigation timer to off and operating the system manually will solve many lawn problems.

Also, there are tools to prevent an irrigation system from coming on during rain or when adequate rainfall has occurred. As a matter of fact, it has been state law in Florida for every automatic irrigation system to have a rain shutoff device installed since 1991.

Florida Statutes, Chapter 373.62 – Water conservation; automatic sprinkler systems states, “Any person who purchases and installs an automatic lawn sprinkler system after May 1, 1991, shall install a rain sensor device or switch which will override the irrigation cycle of the sprinkler system when adequate rainfall has occurred,”

Rain sensors are available, inexpensive and are not difficult to install. Rain shutoff devices really do work when installed properly. If you do not feel qualified to install such a devise on an existing system, check with a reputable irrigation company.

Water only when lawn indicates that water is needed. When the grass needs water, leaf blades fold along the midrib – like a book closing, footprints remain in the lawn long after being made and the lawn turns grayish in spots, indicating it needs water.

When 30 to 40 percent of the lawn shows these signs of water need, turn the irrigation system on and let it run long enough to apply one-half to three-quarters inch of water. Don’t water again until the lawn begins to show these signs of water need. Watering this way will develop a deep-rooted lawn and landscape. Here’s a UF/IFAS Extension link with more information on lawn and landscape irrigation.

Watering Lawns and Landscapes

Watering Lawns and Landscapes

As the weather warms up, people will be outside tending to their landscapes more often. Part of that tending involves a simple thing that everyone knows plants need: water. And that is correct! Plants DO need water, and most of them need it regularly. However, even with the sandy soils in our area that drain quickly, it is possible to overwater your plants!

Overwatering can cause patchy dieback of shrubs and trees.

It is not uncommon to have a dry spell in the spring or fall in North Florida. Weeks may pass by with little or no rain, until the summer rains settle in. People may set their irrigation systems to deal with the lack of rain, but then forget to change the settings once the water isn’t needed. When plants receive too much water, we see a number of things happen. Trees and shrubs may appear to be deficient of nutrients, displaying yellowed leaves. They may die back and have a patchy appearance. Sprinklers that run constantly and splash water on leaves may increase the number of fungal diseases that plants get. Lawns that stay too damp may start seeing moisture-loving weeds such as dollarweed pop up in profusion. Luckily, we do have some guidelines for how much we should water.

For lawns or landscape plants, it is important to know what plants you are dealing with. Different plants have different needs when it comes to irrigation. Plants should be grouped by their water (and light) needs in a landscape, and irrigation zones should be set with those groupings in mind. Plants that enjoy or tolerate more water include wax myrtle, yaupon holly, swamp sunflower, swamp milkweed, pond cypress, and river birch. Others enjoy drier and well-drained soils, such as yucca, oleander, false rosemary, and turkey oak. To help determine the cultural needs of various plants, try consulting the Florida Friendly Landscaping Guide to Plant Selection and Landscape Design or the Florida Native Plant Society’s website.

When deciding whether or not to irrigate, one thing to pay attention to is the weather. All too often sprinkler systems will continue to run despite the weather – even in the middle of a thunderstorm! Install a rainfall shutoff device or make sure yours is functioning properly to avoid this. Overwatering can lead to unhealthy plants, disease issues, and weed problems.

Improperly placed or calibrated sprinklers can lead to lawn problems!

It can help to learn what a thirsty lawn looks like. Turfgrass that needs a drink will fold up its leaves, become dull bluish-green in color, and footprints will remain instead of the grass springing back. When signs of drought stress are evident, it’s time to water.

How much to water? The recommended amount is ½ to ¾ inch of water per application. Different irrigation emitters put out different amounts of water over time, so some measurement is necessary. Put out some small, straight-sided cans such as tuna or cat food cans in the area to be measured, run the irrigation for 15 minutes, and then measure how deep the water is in the cans. If you’ve collected ¼ inch of water in that time, you’ll know that you need to run the system for 30-45 minutes to give your lawn a thorough watering.

For more watering tips, there is plenty of information available. Check out these links:

Watering Your Florida Lawn

Managing Landscape Irrigation to Avoid Soil and Nutrient Losses

Landscape Irrigation

Winter is Tree Planting Time

Winter is Tree Planting Time

Red Maple
Red Maple structure IFAS Photo: Hassing, G.

January to February is the ideal time to plant trees.  During dormancy, all the energy in a tree is in the root system. They will establish very quickly.  In the spring, they will be ready to grow leaves. Planting and establishing trees is all about managing air and moisture in the soil. The exception is palms. They are not technically trees and should only be planted in the late spring and summer. Three of the most common causes of poor plant establishment or tree death are planting too deep, under watering, and over watering. If appropriate trees are planted at the right depth and they are irrigated properly, the trees will thrive for years to come. As simple as this sounds, problems often arise that lead to poor establishment or plant failure.

Following ten critical steps can ensure proper tree planting:

1. Look up for wires and lights. Make sure that the tree species’ mature size will not interfere with any utility lines.

2. Find the topmost root and treat root defects.   After removing the pot from the tree, remove all excess soil on the top of the root ball, until a root that is similar in diameter to the lower branches is located.  That is the topmost root.  Look for any roots that encircle the rootball, particularly close to the trunk.  Remove any roots that will strangle the trunk.  Cut all encircling roots at the point they turn to encourage root branching. Then, rough up or shave off all the roots on the perimeter of the rootball. If the tree is balled and burlapped, use a metal skewer to locate the depth of the topmost root.

Remove an inch or more for extremely rootbound trees.

3. Dig shallow and wide hole. Using the corrected rootball as a gauge, dig the hole slightly less shallow that the rootball.  Loosen the top six inches of soil around the entire rootball.

4. Carefully place tree in hole. Lower the tree into the hole slowly.

5. Position top root 1-2 inches above landscape soil. Make sure that the rootball is above the surrounding soil grade. If balled and burlapped, the nylon straps, metal pins, burlap on top of the rootball, and wire basket above the grade will need to be removed.

6. Straighten tree. Check the tree from two directions at 90% angles from each other.

7. Add and firm backfill soil. Tamp soil with fingers, not feet.  Do not stomp on the soil.  It will compact the soil and reduce the oxygen to the roots.

8. Add mulch.  Apply a 2–3-inch layer of natural mulch out to the perimeter of the trees branches, or beyond if possible.  However, there should be 1 inch or less mulch on top of the rootball.  Do not allow mulch to touch the trunk.

9. Stake and prune if needed.   If there is a strong steady wind, staking is necessary.  Otherwise, don’t stake. Make sure to do all structural pruning is done at planting time.  Establish a central leader and remove crossing branches. But do not remove the lower branches.  Just reduce the length.  The tree needs to bring food to the lower portion of the trunk to increase the diameter.

10. Water the tree. Don’t walk away until the tree has been watered.  Apply at least ½ gallon.  The tree will need to be watered twice a week for 20-30 weeks.  The larger the tree, the more water needed at each event.  However, if the water doesn’t perk in within a few minutes, reduce the amount being applied.  Overwatering can be as harmful as underwatering.

Summer Tasks

Summer Tasks

Summer should be the time to relax and enjoy the fruit of all the hard work performed in the landscape over the previous winter and spring.  However, there are still some essential tasks that need to be completed during the summer.  Perform them in short energy bursts early in the morning or late in the evening.

1. Aerate Your Lawn

If your yard is starting to look weak and thin, even with fertilizing and proper moisture, it may need aeration.  Aeration, which is creating channels into your lawn, allows water and nutrients to reach the deep roots of your grass more efficiently.

To test if you need to aerate your lawn, shovel up a patch of grass to a depth of at least four inches.  If the layer of thatch is a half-inch thick or higher, your yard would benefit from aeration.  There are self-drive aeration machines and tractor-pulled devices you can rent to make quick work of large areas.  For smaller areas, simply punching multiple holes with a pitchfork will do the job.

2. Fertilize

Gardener fertilizing yard
Commercial landscape fertilizer applicators must obtain state certification.

Turf grass often displays a yellow color during the mid-summer rainy seasons due to the heavy rains flushing nitrogen away from plant roots. If your lawn is looking sad and yellow, chelated iron can often give a temporary green-up. Iron is not a replacement for nitrogen, but it can work well during our summer rainy season.

If you soil test revealed a potassium or magnesium deficiency, summer is a good time to make the last corrective application.  Potassium (K) is an essential macronutrient. Fertilizer bags typically show the percentage of potassium in a product as the third number displayed on the front of the bag (e.g., the “8” in 16-2-8). Potassium acts as a “vitamin” for turf grass, increasing root strength, disease resistance and cold hardiness.

Magnesium (Mg), also a macronutrient, is essential for the production of chlorophyll, necessary for photosynthesis, and also plays a part in the movement of carbohydrates from leaves to other parts of the plant.

3. Don’t Mow Too Short

It’s a natural inclination to want to mow your grass as short as you can, so you have the longest time until you have to mow it again. However, giving your grass a buzz cut every time you mow can hurt your lawn over time.

While some turf grasses can be mowed relatively short, like Bermudas and some Zoysias, most grass types shouldn’t be cut shorter than two-and-one-half to four inches high.  Mowing shorter than that can damage the growth point and leave it susceptible to disease and pest infestation.  It can also dehydrate the grass and lead to long term damage.

5. Water Infrequently but Deeply

One common mistake made by many is watering too often and too shallow.  When only given frequent shallow waterings, grass will begin to grow their roots upwards to take advantage of the small amounts of water, which makes weak and unhealthy.  The grass becomes even more dependent on water and very susceptible to disease and insect attack.

Try watering only once or twice a week, but for a considerably longer time so that the water can penetrate deeper into the soil and encourage downward roots.  Ideally, each irrigation zone is calibrated to determine the length of time it take to deliver ½ – ¾ inch.  Then set the system to run every 3-4 days for that number of minutes.  While checking the irrigation delivery system, make sure the rain shut-off device is working and set to the same ½ – ¾ inch.

6. Prevent Mosquitoes

Summer rains on a nearly daily basis lead to lots of standing water. In less than one inch of water, hundreds of mosquitoes can hatch 3 -5 days later. Not only are these blood-sucking pests annoying, but they can also transmit dangerous diseases like West Nile and Zika Virus.  Even without disease, their bites are painful and irritating.

To prevent mosquitoes, make sure no standing water is allowed to remain in your yard, either in low points or in empty containers like flower pots or wheelbarrows.  Any amount of stagnant water is the perfect breeding ground for mosquitoes.  Take a walk around the yard, dumping out water and disturbing the oak and magnolia leaves that are acting a collection cup.  Treat birdbaths and water features with floating “donuts” specifically designed to kill mosquito eggs.

While getting tasks done in quick morning trips to the yard, make sure to keep hydrated.  Heat exhaustion can happen fast.

Save the Water for the People

Florida is rapidly urbanizing with 1,000 people a day moving into the state.  Many cities in the panhandle have experienced accelerated growth rates over the past ten years. Crestview is one of the seven areas in the state with a population growth of 19% or greater, and the only one located in the panhandle.  The 2030 predictions for Florida are another 6 million people, with counties containing military personnel increasing the quickest.

All of these people need water to meet their daily living needs.  The average person in the United States uses 101.5 gallons of water per day.  Residential water use comprises 61% of the public supply category.  This category is responsible for the largest single portion (43%) of groundwater withdrawal in Florida.  The Floridan aquifer spans an area of about 100,000 square miles in the southeastern United States, including all of Florida, as well as, portions of three other states.  At the current statewide population growth rate, Florida is facing a 300 million gallon per day shortfall of future water needs, possibly as early as 2030.

lawn sprinkler spraying waterTurfgrass is a key landscape component and often the most commonly used single type of plant in the residential landscape. However, on a hot, sunny day in midsummer, the average lawn uses 125 gallons of water per 1,000 square feet.  Although Florida has a humid climate where the precipitation rate, on average, is greater than the evapotranspiration rate, the low water-holding capacity of the soil makes irrigation necessary for the high quality landscapes desired by homeowners.  But, watering the yard requires an entire household to skip a shower, not wash anything and avoid cleaning.  Or, we need to find ways to use a different source of water for irrigation and conserve the potable water for the people.

While the use of reclaimed water for landscape plants has become a standard in many parts of Florida, it has limited availability in the panhandle.  However, there are many ways to reduce and conserve potable water use for those with in-ground irrigation systems.  First, make sure you have a functional rain shut-off device.  By design it will prevent the system from running when it has recently rained.  On average, the panhandle has received rain about every 4 days this year.  Besides, Florida law requires a rain shut-off device for all irrigation systems, new or old.

Then, calibrate each zone to determine the length of time required to deliver ½ inch of water.  This can be determined by placing 10 or more, short, straight-sided containers throughout the irrigation zone.  Run the system and look at each container, measuring the depth with a ruler.  Adjust the run time so the system only delivers ½ inch.  Now set the clock to run 2-3 times a week for that length of time.  It’s that simple.  And the water savings is significant. For these and many other irrigation tips, visit askIFAS at

Calibrate Your Irrigation System for a Healthier Lawn

Calibrate Your Irrigation System for a Healthier Lawn

Calibrating or determining the rate of water your sprinkler system applies is an easy job.

Here’s how to do it:

  1. Obtain 5 to 10 straight-sided empty cans such as tuna fish or soup cans.
  2. Place the containers randomly within the irrigated area so that they catch the water when the irrigation system is running. This needs to be done for each irrigation zone, separately.
  3. Turn the water on for 15 minutes.
  4. Use a ruler to measure the depth of water in each can. The more exact your measurement, the better your calibration will be. Measurements to the nearest 1/8 inch are adequate.
  5. Determine the average depth of water collected in the cans (add up the depths of water measured in each can and then divide by the number of cans).
  6. To determine the irrigation rate in inches per hour, multiply the average depth of water times four. For example, if you collected an average of ¼ inch of water in the cans as a result of letting the irrigation run for 15 minutes, the irrigation zone would need to run for 30 minutes to apply ½ inch of water, or 45 minutes to apply ¾ inch of water, etc.

It’s best to do this calibration exercise during the same time of day the system normally runs so that water pressures are similar.


Spread head irrigating lawn

Irrigating lawn. Photo credit: Larry Williams

Here’s why calibrating your system is important.

When a timer/controller is set to come on frequently for short intervals of time (every other day for 20 minutes for example), the result will be a shallow, weak root system and a lawn that becomes dependent on its shallow roots being watered frequently. Also, watering frequently benefits certain weeds such as dollarweed and nutsedge while weakening the lawn.

To develop a deep, strong root system and a lawn that will go through hot, dry weather in better shape without requiring water as often, switch the automatic timer to manual.


Watering a lawn on an as needed basis is the best way to water correctly and develop a deep-rooted lawn. This is the reason for calibrating your irrigation system. You should apply ½ to ¾ inch of water to the lawn only when the grass indicates that water is needed. When the grass needs water, the leaf blades fold along the midrib (like a book closing). Also, footprints or tire tracks remain in the lawn long after being made. And, the lawn turns grayish in spots, indicating it needs water.

When 30 to 40 percent of the lawn shows these signs of water need, turn the irrigation system on and let it run long enough to apply ½ to ¾ inch of water. Don’t water again until the lawn begins to show these signs of water need. Don’t water when adequate rain has occurred.

The best time to observe these signs of water need is during the evening when the grass is not in full sun or under heat stress. It’s best to irrigate during early morning hours to prevent lawn diseases and to minimize water lose due to wind and evaporation. The lawn grass is a great indicator for when most other established plants in a landscape need water as well.