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How to Prevent Poa Annua (Annual Bluegrass) From Invading Your Lawn?

This is a reminder for all of you who have asked me about killing Poa Annua (see photo) back in spring. Now is the time to put down a preventer before it has a chance to germinate this fall.

This is an early spring picture of Poa Annua in a Bermudagrass lawn.  Notice the light colored seeds.  (Click photo to enlarge)

This is an early spring picture of Poa Annua in a Bermudagrass lawn. Notice the light colored seeds. (Click photo to enlarge)

Lawn weeds like Poa Annua (Annual Bluegrass), Common Chickweed, and Henbit are “Winter Annuals”.   This means they germinate in fall, thrive in spring and then die during summer, but not before scattering seed so the cycle can start all over again in fall. (“Summer Annuals”, like Crabgrass, Foxtail and Barnyardgrass, have the opposite cycle of germinating in spring, thriving in summer and dying just prior to winter, but not before scattering seed so the cycle can start all over again in spring.)

If you vowed last spring that you wanted to stop these winter annual weeds from invading your lawn, you need to pick up a bag Scotts Halts or Scotts Turf Builder with Halts so you can treat your lawn now. (One of these Halts products is the correct product to use even though it says to apply in spring to prevent crabgrass.  Read further in the directions and you will see info about applying this time of year to prevent Poa Annua and other winter weeds) Be sure to water after application.

Caution: If you are planning to plant grass seed this fall, you should not spread weed prevention in those areas as it will keep your good grass seed from germinating.

Five Most Asked Lime Questions

Since fall is a great time to put down lime, doing a soil test now will tell you if your lawn needs lime and how much lime it needs.

Since fall is a great time to put down lime, doing a soil test now will tell you if your lawn needs lime and how much lime it needs.

Why spread lime on a lawn?

Answer: Lime helps to raise the soil pH level in acidic soils. Soil pH is a measure of how acidic or alkaline your soil is. A pH of 7 is neutral, acidic soil registers below 7, and alkaline soil above 7. Your lawn can tolerate a fairly wide pH range of 5.5 to 7.5, with 6.5 being the ideal pH for growing grass. When your pH is in the ideal range other nutrients in your soil and in the lawn food you spread are more available to your grass plants. When the pH is outside of this ideal range, some of the nutrients get locked up by the soil and your grass can suffer.

What areas of the country usually need lime to raise soil pH?

Answer: Many lawns in the Northeast, Mid-Atlantic, Southeast, and Northwest are growing in native soil that is naturally acidic. The reason I say that all lawns in these areas are not necessarily growing on acidic soil is because soil chemistry can vary from neighborhood to neighborhood. Also, over the years lime may have been spread on a particular lawn on a regular basis raising the soil pH out of the acidic range. For example, when I first tested my Georgia clay soil I found that it was acidic and needed lime. After several years of putting down lime, a soil test showed my soil no longer needed lime. I plan on testing my soil every 2 or 3 years. Although not as common, you can find acidic soil in other parts of the U.S.

How do you figure out the pH of your soil?

Answer: A soil test kit that you buy in your local garden center can be used to measure your soil pH. Most states offer more complete soil testing through their Extension Service. Check for soil testing labs in your state by doing an internet search with your state’s name and the words “soil testing labs”. Other info on these tests provides values for available phosphorus, potassium, micronutrients and organic matter. As a former County Extension Agent, who looked at hundreds of soil test results for home lawns in Virginia, I know that the primary actionable number to look for is soil pH. You can ignore the other measurements if you are feeding your lawn regularly unless one of them shows up as being abnormally low. For example, if you find that phosphorus is low in your soil, you can substitute a Starter Lawn Food for one or more of your feedings during the year to help raise this important nutrient in your soil.

Will I hurt anything if I put down lime on my lawn without going to the trouble of getting a soil test?

Answer: Probably not in areas that are known to have acidic native soils. It is always a good idea to do a soil test first before spreading lime on your lawn. If you live in any area that I mentioned above that has native soils that tend to be acidic, you could spread up to 50 pounds of lime per 1,000 sq. ft. That’s 250 lbs. of lime on a 5,000 sq. ft. lawn. To spread this much lime, you may find you will need to go over your lawn several times with the spreader set at one of the higher settings. You will also find that granulated lime is easier to spread than pulverized or powdered lime.

When is the best time to put lime on a lawn?

Answer: Lime can be applied anytime the soil is not frozen. Fall is a great time to spread lime since the upcoming alternating freezing and thawing of your soil can help to transport lime from the soil surface down to lower parts of the soil.

Getting Rid of Dallisgrass

One weed that gets confused with Crabgrass this time of year is Dallisgrass.  Folks see Dallisgrass in their lawn and the first thought is that their Crabgrass preventer did not work.   Dallisgrass is a perennial grass that is common in the south and surrounding states to the north.  Since it is a perennial grass, it comes back every year from roots so a spring applied preventer to take care of annual grasses like crabgrass that grow from seed each year only helps to stop some germination of new plants.  Often the only choice is to kill this grass with a weed killer like Roundup.  The downside is that Roundup will kill all vegetation in the area that you spray, however you can seed that area a week later.  You may still have Dallisgrass next year so turf experts suggest you work on the problem for a couple of years.  One thing that helps is to encourage your good grass with regular feedings and mowing at taller mower heights.  The seed heads provide the best way to identify Crabgrass and Dallisgrass.

On the other hand, if you have crabgrass, you can spray with Ortho Weed B Gon MAX plus Crabgrass Killer.   This spray is most effective on young crabgrass.

Dallisgrass is oftern confused with Crabgrass. Dallisgrass seed head on left and Crabgrass seed head on right.

Dallisgrass is oftern confused with Crabgrass. Dallisgrass seed head on left and Crabgrass seed head on right. (click photo to enlarge)

Dallisgrass can be confused with Crabgrass

Dallisgrass can be confused with Crabgrass (click photo to enlarge)

Crabgrass (click photo to enlarge)

Crabgrass (click photo to enlarge)

Fall Vegetable Tips

I almost get as excited about our fall vegetable garden as I do about the upcoming college football season.  The big reason is we eat a big salad almost every night and there is nothing like picking fresh lettuce, spinach and kale leaves just minutes before dinner.  (To really stretch my excitement I guess I could eat a big salad with our fresh veggies during a college football game.  Rita would say I certainly would be healthier than going with the typical football game snacks.)

We get more salad than you can "shake a stick at" from various kinds of lettuce, kale and spinach planted about a month ago. (click photo to enlarge)

We get more salad than you can “shake a stick at” from various kinds of lettuce, kale and spinach. (click photo to enlarge)

There are many vegetables that you can plant now for harvest this fall. You may have space in your garden where some of your early summer vegetables have finished doing their thing. This will give you room to plant lettuce, spinach, turnips, mustard, kale, collards, and other cool weather veggies that are not really bothered by frost. Some of you in Florida, Texas, Arizona and other southern states with mild winters also have the opportunity to plant other vegetables including squash, cucumber, tomato and many others. And do not forget to plant a few containers with lettuce, spinach or a good mesclun mix to set around your deck or patio.

When planting in your garden, replenish your soil by mixing in an inch or two of Miracle-Gro Nature’s Care Organic Garden Soil. When planting in containers, start with a fresh bag of Miracle-Gro Nature’s Care Organic Potting Mix. (Garden Soil is for mixing with native soil in the ground while Potting Mix is for containers and hanging baskets.)  And don’t forget to give your veggies some plant food to maximize your harvest.  If you do not feed them you may end up with puny plants.  We like to use Miracle-Gro Nature’s Care Organic Vegetable Food.

Here is a link to some great Bonnie Plants fall gardening tips and video that will make a big difference in your fall vegetable garden.

What is Best… Lawn Aeration OR Dethatching?

I recommend Lawn Aeration using a machine that removes cores from your lawn in cases where you want to improve your existing lawn by opening up the thatch layer without tearing it up.  A dethatching machine may be a better choice if you are trying to remove dead thatch to expose soil so new grass seeds have a better chance of getting started. 

First let’s talk about thatch.  When a lawn has more than a half inch of thatch; water, air and nutrients may not be getting down to the roots. The tell-tale sign to look for is if your lawn does not really turn a healthy green after feeding. You can check your thatch layer thickness by removing a plug of grass, soil and all, and measuring the brown thatch layer between the green growth and soil layer. If thatch is greater than a half inch, consider aeration or dethatching.

This illustration shows that root depth is restricted by both compacted soil (far left) and too much thatch (2nd from left).  Feed your lawn after aerating.  The result is improved root growth as shown in the far right illustration.

This illustration shows that root depth is restricted by both compacted soil (far left) and too much thatch (2nd from left). Feed your lawn after aerating (3rd from left). The result is improved root growth as shown in the far right illustration.

Since fall is a great time to aerate cool-season grasses, this is a very timely topic for those with bluegrass, ryegrass, fescue and bentgrass. The best time to aerate warm-season grasses is early summer, however if you have a severe thatch problem in your Bermuda, Zoysia or St. Augustinegrass you can aerate anytime your lawn is actively growing.

A second reason to aerate a lawn is if the soil is compacted. You can tell if your soil is compacted if it is difficult to stick a screwdriver into your soil even when it is wet. When a lawn gets a lot of use (like you get with athletic fields or golf courses) the soil can get packed down and compacted, restricting the flow of water and nutrients. There are some tell-tale signs that your lawn may be compacted. Poor drainage is one. If water pools up on your lawn or runs off instead of soaking in, it could be because the soil is compacted. Lawns that look worn-out are often because of compacted soil.

Aerate your lawn by making individual holes around three quarters of an inch in diameter, three inches deep, and no more than 3 inches apart. This is best done with an aerating machine that removes plugs of soil, NOT the kind that just punches spike holes in the lawn. Soil should be moist enough for the machine to remove plugs that are around 3 inches long. Follow up the aeration with a feeding of Scotts Turf Builder or Scotts Natural Lawn Food.

You can rent an aeration machine at many Home Centers and Hardware stores.

Oh, here's some good news:  after aerating, you can leave the plugs on your lawn.

Oh, here’s some good news: after aerating, you can leave the plugs on your lawn.

August Lawn Checklist

Some lawns need feeding.  Most Southern lawns (like Bermuda, St. Augustine and Zoysia) love to be fed at two month intervals from spring to fall for a total of about 4 feedings a year.  Centipede only likes two or three feedings a year from late spring to late summer. Scotts GreenMAX Lawn Food, Scotts Turf Builder or Scotts Natural Lawn Food are good choices for this time of year.   Northern lawns (like Bluegrass, Fescue and Ryegrass) appreciate two or three feedings from mid-August to Late November.  As the day and night time temps drop into the 80’s or below this month, you can give your lawn the first of these important fall feedings.

This Northern lawn is looking very good in August because it has received regular feedings.

This Northern lawn is looking very good in August because it has received regular feedings.

Problem lawns can be “killed and replaced”.  This “kill and replace” strategy is for lawns troubled by the kind of grassy weeds you can’t kill without killing your good grass and for lawns you are fighting a constant battle with lawn diseases. We are approaching the best time of year to renovate cool-season grass lawns (like Bluegrass, Ryegrass and Fescue). Note: warm-season grass lawns (like Bermuda, Zoysia, St. Augustine and Centipede) are best started in late spring.  Click here to link to one of my blog postings that outlines how this is done.

Continue to protect your lawn from insects.  Tiny insects can attack your lawn during summer causing it to thin and turn brown.  One indication that they may show up is when you see moths fly from your lawn when you mow or walk on your grass during early evening hours.  These moths do not damage your lawn, however they lay eggs for insects like sod webworms and cutworms that can cause your lawn to thin and turn brown.  Other insects, like chinch bugs can show up about the same time.  You can protect your lawn while feeding it with a special summer lawn food called Scotts Turf Builder with SummerGuard.  This product also takes care of other insects like fleas, ticks and ants.  If your lawn does not need feeding, you can spread Ortho Bug B Gon MAX on your lawn to take care of any insect problems.  Oh by the way, it is ok if you still see some moths after treating, since they do no damage.  You have protected your lawn from the damage caused by their hatching eggs for about 6 weeks or so.

Lawn moths fly from the lawn during the evening or when mowing.  They lay eggs for sodweborms or cutworms that can cause your lawn to thin and turn brown during summer.

Lawn moths fly from the lawn during the evening or when mowing. They lay eggs for sodweborms or cutworms that can cause your lawn to thin and turn brown during summer.

Kill lawn weeds if they are growing.  Weeds are harder to kill if they are not actively growing.  Most weed controls are designed to work if your temperatures are between 60 and 90 degrees, so check the label for suggestions to get best results.  Ortho Weed B Gon MAX plus Crabgrass Killer takes care of most weeds.  Do not use on Floratam (a variety of St. Augustinegrass), Centipede or Bahiagrass lawns.  Ortho Nutsedge Killer and Ortho Weed B Gon Chickweed & Clover Killer are also options depending on where you live and your lawn type.  Note:  If you are planning to put down grass seed in the weeks ahead be sure to check weed control directions for waiting periods.  For example, some weed controls suggest you should wait a month after using before seeding.

You think you are getting rid of Nutsedge (also called Nutgrass) because it is easy to pull. However, it quickly grows back from the bulb-like roots that are left behind in your soil.

You think you are getting rid of Nutsedge (also called Nutgrass) because it is easy to pull. However, it quickly grows back from the bulb-like roots that are left behind in your soil.

Mow your grass taller.  Taller grass blades mean deeper roots to match the leaf growth. So adjust your mower to leave your grass height at around 2-1/2 to 4 inches for Bluegrass, Ryegrass and Fescue, 2 to 4 inches for St. Augustinegrass and Bahiagrass, 1 to 3 inches for Centipedegrass, 1/2 to 2 inches for Bermudagrass, 3 /4 to 2 inches for Zoysia

Water Sensibly.  If you are able to water without restrictions and you want to keep your grass from going dormant, a half inch twice a week is better than a small amount every day. This helps to encourage deeper roots. Place a tall straight sided/flat bottomed glass or a rain gauge on your lawn while your sprinklers are running then measure the depth of water that accumulates in the glass to help calculate how long to run your sprinklers to put down a half inch. You would only need to do this once to help figure out your sprinkler system. If you can, water in early morning when there is less wind and evaporation.

A half inch of irrigation twice a week helps to create deeper roots.  Daily watering encourages shallow roots.

A half inch of irrigation twice a week helps to create deeper roots. Daily watering encourages shallow roots.

How To Tell If Your Lawn Has Fungus?

Those brown areas in your lawn could be caused by a lawn disease (fungus), lawn insects, or hot dry weather.  So how do you figure out if a lawn disease is the problem?

Experts look for brown, black, white or reddish spots on the individual grass blades or circular brown patches of grass where the fungus has spread from the center.  Sometimes lawn fungus problems show up in the same area each year.

There are a range of lawn diseases that show up with warm, humid weather.  These fungus problems are especially active when your night temperatures and humidity do not drop very much from the levels you are experiencing during daytime hours.  You can help your situation by not watering your lawn in the evening as this helps to hold humidity at high levels next to your grass plants for an extended period of time.  Experts will always suggest that if you have to water, it is best to irrigate in the morning.  Lawns located where air movement is restricted by a fence or hedge generally experience more lawn disease problems as compared to more open areas.

You can help strengthen your grass by not under or over-feeding and by mowing at a taller height.  You can also help strengthen your lawn with the newer grass varieties.  Many of the grass seed varieties that are available in the top-of-the line seed blends today, like the Scotts Turf Builder Grass Seed line, have improved resistance to lawn fungus disease built right in compared to the older grass varieties.

Use the photos and descriptions below tell if you have some of the more common lawn disease problems in your lawn.

If you need to protect your grass from lawn fungus, Scotts Lawn Fungus Control is a good “systemic” cure, which means the active ingredient is absorbed into your grass plants to protect them from the inside.  (Other “contact” controls are not as effective because they must stay on the grass blade leaf surface which means you need to spray frequently as you mow).

Brown Patch on Tall Fescue – Circular patches of dead grass are a symptom of several lawn fungus problems such as Brown Patch and Summer Patch show up during periods of warm temperatures and high humidity.  Click photo to enlarge

Brown Patch on Tall Fescue – Circular patches of dead grass are a symptom of several lawn fungus problems such as Brown Patch and Summer Patch show up during periods of warm temperatures and high humidity. Click photo to enlarge

Dollar Spot on Kentucky Bluegrass – Individual grass blades have white blotches edged in reddish brown the shape of an hour glass. Other lawn diseases that show spots on grass blades are Rust and Helminthosporium Leaf Spot.  Click photo to enlarge

Dollar Spot on Kentucky Bluegrass – Individual grass blades have white blotches edged in reddish brown the shape of an hour glass. Other lawn diseases that show spots on grass blades are Rust and Helminthosporium Leaf Spot. Click photo to enlarge

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