Crabgrass or Green Grass?Monday, April 4, 2011 at 4:14 pm
Posted by Jonathan Green
Tags: Crabgrass , crabgrass preventer plus green-up , crabgrass preventer plus new seeding & spring
Summertime droughts kill many lawns but the crabgrass survives! Crabgrass is a very resilient plant that even thrives through heat and drought. Why do we have such a difficult time controlling crabgrass? Will you have crabgrass this year? Do you feel lucky?
It takes more than luck to control crabgrass effectively. The best defense against crabgrass is a thick, healthy growing lawn. You accomplish this by introducing Jonathan Green superior turf grass mixtures and following our annual lawn care program. It is important to understand the life-cycle of crabgrass. Crabgrass is an annual plant that is widespread throughout the USA. Like all living things, it strives to survive and produce the next generation of plants for years to come. Crabgrass germinates in the spring when soil temperature, not air temperature, reaches about 50-55 degrees Fahrenheit. Crabgrass grows horizontally along the ground so even your lawn mower has a hard time mowing it away since the seeds of the crabgrass plant are very small. During August and September undisturbed crabgrass plants will produce seed heads thus insuring next year’s crop of crabgrass plants. If this cycle is not stopped, these seeds lay dormant in the soil until the following spring, when they are ready to jump into action again. Crabgrass is killed with the fall frosts leaving a brown crab-like skeleton in its place.
By interrupting the germination of these existing crabgrass seeds this spring, we can eliminate most crabgrass plants in your lawn this summer. An application of Jonathan Green Crabgrass Preventer plus Green-Up Lawn Fertilizer should be your first order of business following your spring cleanup. The fertilizer greens up the existing lawn while the invisible barrier lies in the top layer of the soil. It is important that you do not rake the lawn after the application. If you do, you will disturb the invisible preventative barrier and crabgrass seeds will most likely germinate.
You may have wondered, “When does crabgrass stop germinating?” Surprisingly, crabgrass does not stop germinating until the beginning of August. Therefore, crabgrass can continue to germinate through most of the summer months. Perhaps this explains why many of us have had trouble completely controlling crabgrass. The only way to address this problem would be to apply a second application of Crabgrass Preventer plus Green-Up Lawn Fertilizer around June 1st. Since crabgrass is not visible in the lawn at that time, most homeowners will not think of this approach. However, if you have continuing problems over the years with excessive crabgrass you should probably try this second application. This will help to extent the threshold of control.
Many crabgrass controls in the market contain dinitroanaline chemistry known as “yellow” products. These products where developed in the last 40 years and need to be applied as a “pre-emergent” to create a barrier in the top layer of the soil before the crabgrass seeds germinate. Once the crabgrass seeds sprout in the spring, these controls disrupt the seed germination and they die. These types of controls do not work if applied too late since the chemical barrier needs to be set in the ground before the crabgrass germinates. New chemistry in the 1990’s came on the market using dithiopyr or Dimension. Crabgrass Preventer plus Green-Up Lawn Fertilizer features Dimension and offers crabgrass control before and after it germinates, up to the three-leaf stage. Dimension is also clear, odorless and non-staining and uses a very small amount of active ingredient making it more environmentally friendly. Jonathan Green Crabgrass Preventer plus Green-Up is very stable and will not move beyond the top few inches of the soil layer. Do read the label of your particular product. Please take note, if you have a water garden, most crabgrass preventers will kill koi or other fish if you accidentally spread it in the water. Remember that your crabgrass control is photosensitive. Therefore sunlight will rapidly break down crabgrass pre-emergents in bare soil.
You cannot use these traditional crabgrass preventers if you want to seed this spring. You do have an alternative; use a product which contains Siduron or Tupersan like Jonathan Green Crabgrass Preventer plus New Seeding Lawn Fertilizer. This application allows you to plant grass seed on the same day without injuring the new grass seedlings. Or, switch your program around and apply your grass seed in early spring with a Jonathan Green New Seeding Lawn Fertilizer. After the new seed germinates and is mowed once or twice, apply your Crabgrass Preventer plus Green-Up Lawn Fertilizer in late spring.
There are many other factors that contribute to why crabgrass controls fail. The timing of applications is probably the biggest factor. The chemical barriers in pre-emergent products only last for a few months in the soil to prevent crabgrass. If you apply pre-emergent controls too early in spring, the chemical control will diminish over time. This will happen especially if we have a cold, wet spring, which delays the crabgrass seed from germinating. If you apply the pre-emergent control before the ground temperatures reach 50-55 degrees, again, the chemical control is somewhat wasted. The “old wives tale” was to apply your pre-emergence when the forsythia blooms. If you do not know what forsythia looks like, or you do not have any forsythia in your area, put a soil thermometer in a landscape bed at least 10 feet from your house foundation. It will tell you when the soil reaches 50-55 degrees to apply your controls.
Crabgrass frequently dominates the area between the sidewalk and curb. This soil tends to not be of the best quality thanks to snow melting salts and dog walking. Extra heat builds in the soil from the concrete and blacktop. The edge of the driveway also releases heat which crabgrass likes to grow in while your lawn grasses do not. What about all of the shuffling of your feet along the side of the driveway when you enter and exit your car? What about a lot of kids playing and pets traffic in your yard? This repeated scraping of the grass helps to break down the invisible barrier allowing crabgrass to break through.
While we are talking about our driveways and sidewalks, do you or your lawn service use a power edger to trim these areas? Using an edger regularly brings up weed seeds to the soil surface helping them to establish, another reason we think our crabgrass preventer failed. Speaking of mowing, are you mowing your lawn too short putting it under stress allowing crabgrass to take over? Be sure to mow 2.5 to 3 inches to help the lawn grow thick so it crowds out crabgrass. Also, remember crabgrass does not grow in shade so you do not need to apply preventers in shaded areas of your lawn.
What about taking the organic approach? If you experience continued frustration battling crabgrass in your lawn using traditional methods, go organic and choose Jonathan Green Organic Weed Control. Follow the organic method of lawn care; feed the soil to help the soil feed the grass plant. Organics may take more time to control crabgrass, but by improving the soil with organics, you get a thicker, greener lawn, crowding out future crabgrass generations. Corn gluten is the only true organic weed preventer and can be found in Jonathan Green Organic Weed Control. It must be put down prior to the target weed seeds germination which would be early spring for crabgrass. Organic Weed Control controls crabgrass and over 20 other grassy and broadleaf weeds and fertilizes the lawn too! Consider using it at the higher 20 lbs. per 1,000 square feet rate for improved crabgrass control.
Wow! Now we know a lot of reasons why crabgrass shows up in our lawns. Do your part to eliminate crabgrass this year and good luck!