by Larry Williams | Mar 17, 2015
Cold injury to lawn from too early fertilizer application. Credit: Larry Williams
It’s too early to fertilize our warm-season lawn grasses now. This includes the use of fertilizers contained in weed-and-feed products.
There are a number of reasons why it’s best to wait to fertilize your lawn.
First, the soil temperature is too cool for grass roots to have access to some of the fertilizer elements. For example, iron and potassium are poorly available until the soil warms up in spring. Some nutrients leach below the grass roots because the lawn can’t use them yet. This results in waste of fertilizer, time and money.
Secondly, fertilizing too soon can induce nutrient deficiencies and off color areas in your lawn. This is one cause for bright yellow areas in lawns during early spring. Nitrogen is readily taken up by the lawn, even under cool soil conditions, and stimulates early green growth. Early lawn growth is dependent on iron also being readily available. However, iron is poorly available under the cool soil conditions of late winter and early spring. Therefore lawns turn yellow in areas due to an iron deficiency caused by an early fertilizer application. Many times, as soil temperatures warm during mid April and May, the iron becomes available and the lawn turns green. So why not avoid this scenario by waiting until mid April to fertilize your lawn?
It takes consistently warm night temperatures to allow the soil to become warm enough for best root growth and optimal uptake of fertilizer.
Thirdly, the young, tender grass roots that are beginning to grow in early spring are easily burned by the fertilizer.
Fourthly, fertilizing too early can stimulate early lawn growth, which is tender and easily injured by a late frost. The average date for our last killing frost is mid March.
Also, be very cautious about using weed-and-feed products that recommend a late winter application. These products are usually high in nitrogen, which will cause your lawn to begin growing too early. If you’re trying to control weeds, it’s best to apply your herbicides separately from fertilizer, anyway.
In North Florida, it’s best to wait until your lawn has completely greened up in spring before applying any fertilizer.
Waiting allows for more efficient use of the fertilizer. You will not injury you lawn by waiting to fertilize but you can certainly injure your lawn by fertilizing too early.
So, have patience, allow your lawn to green up on its own and then fertilize, even if it’s not until mid April or May.
by Larry Williams | Feb 17, 2015
Diseased Turfgrass – Image Credit Matthew Orwat
With a few nice late winter days, many people get a good dose of spring fever. But be careful when the fever hits you. Don’t fertilize your lawn too early. The fever may turn into a lawn “headache”.
Wait to fertilize. Fertilizing while the soil is too cool can result in nutrient deficiencies such as iron deficiency causing yellow areas in the lawn. Fertilizing early can result in injury to a lawn’s roots from fertilizer burn. Or tender growth promoted by an early fertilizer application may be injured by a late frost or freeze. Have patience, allow the lawn to green up on its own and then fertilize, even if it’s not until mid April or May.
Get the numbers right. Our lawns need almost the same amount of potassium as compared to nitrogen. Getting this right can make a difference in the long-term health of your lawn. Look for a lawn fertilizer with an analysis such as 8-0-8, 10-0-10, 15-0-15, 18-0-18, 15-2-15, 16-0-8, etc. Look for a fertilizer with a 1:1 ratio of nitrogen to potassium. These numbers provide the buyer important information. The first number is the percent nitrogen (N), the second number is the percent phosphorus (P) and the third number is the percent potassium (K). Adequate potassium has been linked to reduced disease problems, drought and cold tolerance and enhanced root growth.
Use low phosphorus. Lawn grasses use much less phosphorus than nitrogen or potassium. Because of this and because phosphorus has been implicated as a cause for problems in our surface waters, it’s recommended to base phosphorus rates on the results of a reliable soil test. In absence of soil test results, select a fertilizer with 2% or less phosphorus such as 15-2-15, 8-0-8, 16-0-8, etc. It’s best to base P applications on the results of a reliable soil test.
Don’t fertilize too late. The latest month to fertilize our warm season lawn grasses in North Florida as recommended by University of Florida turfgrass researchers is mid September. If you have centipedegrass, it’s recommended to fertilize no later than July.
Measure your lawn. Most homeowners apply too much fertilizer because they do not know the square footage of their lawn. Measure the size of your lawn (front, back and side yard) and err on the side of using less fertilizer than recommended.
by Mary Salinas | Feb 2, 2015
So often, homeowners wait until weeds have overtaken their lawns in mid-summer before looking for a course of action to control them. Unfortunately, when weeds get to maturity and start producing flowers and going to seed, they are usually quite difficult to control.
[important]The best strategy is to prevent the weeds from getting established in the first place![/important]
Florida pusley, an annual weed that can be controlled with preemergence herbicides. Photo credit: Mary Derrick UF/IFAS Extension.
When properly applied, a preemergence herbicide forms a chemical barrier on the surface of the soil that kills newly germinated seeds when they grow and contact that barrier. Be sure to follow label directions carefully as it is crucial to apply the correct amount and water it in correctly. The soil surface should not be disturbed after application to ensure that the chemical barrier remains intact.
Keep in mind that preemergence herbicides only prevent annual weeds! They do not control weeds that have already emerged.
In North Florida, the time to apply a preemergence herbicide to your turfgrass is coming soon. As a general rule, March 1 is an ideal time. Another indicator that the time is right is when the daytime temperatures reach 65°F-70°F for 4 to 5 consecutive days as that sustained warmth will prompt weed seeds to germinate. Oftentimes, this is also when azaleas or dogwoods start blooming and that can clue you into when to apply the herbicide. For best results, follow up with a second application in 6 to 9 weeks to control those seeds germinating later in the season.
Always follow the label instructions precisely when applying any herbicide! Ensure that you apply the product at the correct rate, that it is suitable for your specific turfgrass and situation, and that it is watered in correctly. For any pesticide, the label is the law!
If your lawn has problems with winter weeds, make a note on your calendar to apply a preemergence herbicide about October 1 in North Florida or when nighttime temperatures drop to 55°F-60°F for several consecutive days.
For more information on weed control in lawns:
Weed Management Guide for Florida Lawns
For general information on lawn care in Florida:
UF/IFAS Gardening Solutions: Lawns
by Les Harrison | Nov 18, 2014
Even though the lawn and landscape are going dormant, there is much which can be done now to prepare for Spring 2015.
Even though it is not officially winter and the landscape is becoming dormant. With the exception of live oak trees, all the plants and trees which lose their leaves are now dropping them to the ground.
For the north Florida homeowners consumed with plans for the holidays, late November is a tempting time to let the landscape take care of itself during this winter’s nap.
This is not necessarily the best plan. There are plenty of task to handle which will make the upcoming growing season more productive and easier.
First on the list of winter’s lawn and garden task is taking a soil sample. It is simple, inexpensive, and efficient from both an economic and environmental standpoint.
Stop by the local UF/IFAS County Extension Office to pick up a free kit which is used to mail the samples, with a processing fee, to the UF Soil Test Lab. The report is usually returned in under two weeks.
Depending on the analysis chosen, the report will deliver the samples soil pH, or the nutrients needed and the soil pH. This is useful information for the spring and summer growing season, and during winter’s dormant period.
People with wood burning fireplaces should be particularly aware of the soil pH which is a measure of acidy or alkalinity. The pH range helps determine the potential success of plants, vegetables and shrubs which will grow in the sampled soil.
Fireplace ash is alkaline and an excellent soil amendment, if the soil pH is too low. However, if the soil pH is too high, then the fireplace ash only aggravates the existing problem of growing desirable plants and grasses.
Many Florida soils tend to have a high concentration of phosphate, an important and useful plant nutrient in the right quantities. Having a soil analysis early which identifies the amount of phosphate available in the land gives the homeowner or garden manager plenty of time to locate a source of blend-fertilizer with the correct amount of phosphate.
The second task on the list is to manage the leaves, mulch and thatch. Each has the potential to be an asset to the landscape, or a hazard.
Leaves should be raked up before they have the time to smother the grass. A carpet of leaves in the yard may appear very seasonal, but usually work against the objective of those who ultimately want a green grassy yard.
As leaves decompose, they leach acidic nutrient into the soil. This is especially true of oak leaves and pine needles.
Another issue is leaf litter and thatch, produced from grass clippings, which will provide an ideal breeding ground for fungi and diseases. The cool, moist recesses common to thatch will incubate any number of problems which will appear in the spring to ruin the perfect yard.
Rake the leaves and use in flower beds or compost heaps. The shrubs will overwinter better with the leaf insulation which keeps the root zone at the correct moisture level and provides desirable nutrients to the plants.
Dethatch lawn mechanically to remove excess debris. Use the excess organic material as mulch or in a compost pile.
The landscape will show its appreciation by returning in a healthy and strong condition in Spring 2015.
To learn more about winter landscapes visit the nearest UF/IFAS County Extension Office. Additional information will be found in the Florida Lawn Handbook
by Mary Salinas | Sep 16, 2014
Many of us have a tendency to want to spoil those we care for – our significant other, our pets, our children, even our lawns. Some homeowners who long to have a lush, green, healthy lawn tend to spoil their lawns with lots of water. Their lawns should not suffer through a dry, thirsty day! However, spoiling a lawn with too much water can literally be killing it with kindness. (Keep in mind that we are discussing established turf, not newly installed lawns; new lawns do need special care.)
Turfgrass that is overwatered can suffer several fates. Roots can stay shallow near the surface and not dig deep into the soil as they should. A deep root system allows the turf to be more resistant to stress from drought, disease and abiotic factors such as wear from traffic. Excessive water leads to excessive lush growth – that may sound like a good thing, but it’s not. Excessive lush growth leads to thatch build-up and it creates a perfect environment for pests and diseases. An abundance of water also assists those nasty weed seeds to germinate and compete with your turfgrass.
So how do you know how much irrigation is best for the health of your lawn? That depends on the temperature, time of year, the type of turf and your soil type. Irrigate just enough to get water to the root zone without leaching beond that zone. Usually, that amount is 1/2″ to 3/4″ of water each time you irrigate. How often, then, do you turn on those sprinklers?
Let your lawn get thirsty before you water. University of Florida research shows that lawns that dry out and start to show a little drought stress before getting more water actually perform better in the long run. So wait until the leaf blades start to fold, the blades start to look a bit off-color, or you can start to see footprints where you’ve walked.
For lots of great information and publications on caring for your lawn, consult the Your Florida lawn website.
by Taylor Vandiver | Sep 9, 2014
What’s eating my lawn? Does your grass look ragged in areas, as if someone randomly used a weed-eater here and there? Are you noticing brown patches that have a closely clipped appearance compared to other areas of your lawn? Your turf may be playing host to Tropical Sod Webworm.
Sod webworm damage in a home lawn. Photo courtesy UF/IFAS.
Sod webworm damage is subtle at first. You have to look closely to notice larval feeding damage. However, an easy indication of their presence is the light tan/brown colored moths, which are the adult stage of the pest. You may see them fly up as you walk through your lawn or if you disturb a nearby bush. The moths do not cause any damage to the turf, but they are depositing eggs, which will result in their offspring, the caterpillars, who do all the chewing damage.
The larvae are gray-green and have spots on each segment. The mature larvae can be up to 1 inch in length. Larvae will curl up in the soil during the day and feed at night. So if you happen to notice caterpillars feeding during the day, it’s probably not sod webworm. You will notice chewed notches along the leaf blade, holes in the leaf and even leaf blade skeletonizing. The older the larvae are, the more they will eat. Damage may start out as a ragged appearance in your turf, which can be hard to diagnose. However, if left unchecked, sod webworm can cause considerable injury to your lawn.
Sod webworm larvae. Photo courtesy UF/IFAS.
If you are uncertain of their presence you can always use a soap drench to flush out larvae. Mix 2 tablespoons of dish soap with 2 gallons of water and pour it over a damaged area (about 3 square ft.). The soap mixture will irritate the pest and bring them to the surface so you can easily identify them. If nothing appears in the area tested move to another damaged site and try again. Here is a link to a video that will give more information on identifying Tropical Sod Webworm.
Tropical Sod Webworm is considered a pest of all warm-season turfgrasses. However, St. Augustinegrass is most commonly affected. The best way to prevent a pest infestation is to use proper cultural maintenance practices for your lawn type. However, if the pest does appear, chemical control should be targeting the larvae stage of the pest. There are multiple products marketed to control lawn caterpillars. However, you may want to consider using B.t. (Bacillus thurengiensis), which is a bacterium that will only harm caterpillars and not bother beneficial insects that may be in your lawn. For more information you can contact your local extension office.
