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Prevent Poa Annua (Annual Bluegrass) Now

September 1, 2012

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.)

This is an early spring picture of Poa Annua in a Bermudagrass lawn.

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.  (This is the right product to use even though it says prevents crabgrass.)

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

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  1. Philip Lee Lum permalink

    You may recommend applying halts line of product to prevent annual poa but nobody carries it this time of year! Try going to the store and locating some.Impossible to find in my area of New Jersey (Mercer County)

    • Hi Philip
      Sorry you are having trouble finding Halts. You can use Halts, Turf Builder plus Halts or Super Turf Builder plus Halts. You may want to call our Help Center at 1-800-543-8873 and ask for suggestions for Scotts retailers near you.

  2. Have been having a heck of a time with henbit infesting my tall fescue lawn over the past 3-4 years. Could you provide some advice as to what I should do in the coming months to control this problem. There is a section of my lawn that I plan to reseed; however, after clearing it last fall with RoundUp, it has become overgrown during the winter months with henbit. For the remaining portion of my lawn which will not be reseeded but does have small areas of henbit growing, I put down Scotts TB with Crabgrass Preventer on Feb 24. Any specific steps I should be following with the henbit problem would be greatly appreciated.

    • Henbit is a winter annual, which means it germinates in fall, grows during cooler months in winter and spring, produces seed after if flowers in spring, then dies with the hot weather. The cycle is repeated year after year. (Crabgrass has the opposite cycle and is called a summer annual.) When you killed off all the competition around it last fall, it had lots of room to thrive. If you put the crabgrass preventer down in early September you can prevent the new seeds from growing. The caution is that you can not seed for 4 months after spreading the crabgrass preventer. Henbit can be sprayed with Ortho Weed B Gon MAX on a day that reaches 60 degrees. You will need to wait 1 month to seed after spraying. Hope this helps.

      • I put down TB with Crabrass Preventer Feb 24, 2013 for the portion of my lawn that I do not plan to reseed this year. Will that do anything to kill off the henbit that is currently growing in this portion of the lawn? I note that the Ortho Weed B Gon product suggests that you can apply the product when daytime temps are above 45 degrees. Are you suggesting that I should wait for daytime temps to reach 60 degrees for henbit?

      • Your recent application will not kill your existing Henbit. An application in Sept before germination will do the job. However, your timing is good for preventing crabgrass. You can spray at lower temps than I stated, however I think you will get better results if the Henbit is actively growing and able to absorb the weed killer. I gave you a higher temp as I think you will get a little better control. Good Luck.

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