When Should I Put Pre-Emergent Crabgrass Control Down On My Lawn
03/16/11
Crabgrass seeds can germinate each year when nighttime soil temperatures reach over 50 degrees for 3 days. This "wakes up" the seed, and starts it on its process of growing up to be your worst nightmare.So you can diligently observe soil temperatures, either through your own monitoring, or a local source. Missouri State University provides this information on a website as a guideline for when to apply crabgrass preventer and other products.How much of the current crabgrass seed lurking in your yard will germinate this early? The earlier that you apply the preemergent, the sooner it will lose effectiveness. The duration of effective control depends on the type of product, and how heavy of a concentration you apply.
Crabgrass seed doesn't line up at the germination window like holiday shoppers do at stores on the morning after Thanksgiving. Some are late sleepers.Researchers at the University of Maryland determined that the minimum daytime soil temperature to observe the initial emergence of crabgrass was 54 degrees.The major emergence of crabgrass, however, did not appear until soil temperatures were at least in the range of 60 to 70 degrees.This explains something that you have probably observed. There seems to be no end to the appearance of new crabgrass throughout the warm months of the year. Individual seed specimens will vary by size, maturity, and depth in the ground, as to when they are ready to germinate.Soil temperatures will vary throughout your yard. How much is the soil shaded during the day? The thickness and height of your grass can affect this. So can trees, shrubs and buildings nearby, as well as cloudy days. The amount of moisture present, wind, and more, can also affect temperatures.The end result is, these pesky weeds will pop up consistently over an extremely long growing season. Will the late bloomers be met with preemergent, or will it have worn off already? So there really is not one small window that is fitting for when to apply crabgrass preventerWhat if you miss the early date for applying the preemergent? You watch crabgrass sprouting for a month because you don‘t have a chance to get to yard chores. Does that doom you to allowing the remaining seeds to have their way the rest of the growing season? Certainly not!Take the necessary steps to kill crabgrass plants that showed up early. But why not be in control for the rest of the season? Don't despair because of what all the experts say about the limitations of when to apply crabgrass preventer. Get it down as soon as possible, yes. Get it down as late as possible also.The only thing you have working against you is that most preemergents will lose their effectiveness in extreme heat, when temperatures get over 90 degrees. By this time most of the weeds will have sprouted anyways. But a single short heat wave may not fit that condition.You may have a chance to reduce the crabgrass population by 50 percent or even by just one-third, with a late application. That could translate into less trouble trying to kill mature weeds later on, and especially next year. Let the answer to 'when to apply crabgrass preventer' be mindful of next year's benefits as well as providing some help this season.
Many of you won't bother trying to watch for rising soil temperatures. We all have too much to keep track of without worrying about crabgrass birthdays! Here is a valuable tip on when to apply crabgrass preventer. Watch for weeds sprouting along the edges of concrete. Next to sidewalks, patios, brick edging, and driveways, the temperature will rise more quickly. These materials absorb heat from the sun and transfer it to the soil adjacent to them.Crabgrass seeds frequently get lodged in these edge areas, and they are often the earliest of the weeds to sprout. Watch for these bright green seedlings. When you see them, you have entered the season. Now is your best time for complete control of crabgrass using preemergents.If you take advantage of this early clue, you need to know one thing about selecting a pre-emergent. There is a product that also acts as a post-emergent killer of crabgrass until it grows past the four leaf stage. So even those early "scouts" can be wiped out if you act promptly. It is found as a granular product that is spread over a lawn area and then watered in thoroughly to activate it.
Article taken from, Garden Councelor Lawn Care with permission.
Many of you won't bother trying to watch for rising soil temperatures. We all have too much to keep track of without worrying about crabgrass birthdays! Here is a valuable tip on when to apply crabgrass preventer. Watch for weeds sprouting along the edges of concrete. Next to sidewalks, patios, brick edging, and driveways, the temperature will rise more quickly. These materials absorb heat from the sun and transfer it to the soil adjacent to them.Crabgrass seeds frequently get lodged in these edge areas, and they are often the earliest of the weeds to sprout. Watch for these bright green seedlings. When you see them, you have entered the season. Now is your best time for complete control of crabgrass using preemergents.If you take advantage of this early clue, you need to know one thing about selecting a pre-emergent. There is a product that also acts as a post-emergent killer of crabgrass until it grows past the four leaf stage. So even those early "scouts" can be wiped out if you act promptly. It is found as a granular product that is spread over a lawn area and then watered in thoroughly to activate it.
Article taken from, Garden Councelor Lawn Care with permission.
