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GARDEN TIME with DOUG – Crabgrass, A Real Pain in the Grass!

By Doug Hensel
Doug's Blog

I CREDIT THE VIRGINIA COOPERATIVE EXTENSION FOR THE CREATION OF THIS CATCHY TITLE.

It’s a good phrase, don’t you think?

Crabgrass is the number one weed in lawns here in Virginia. It is now mid-February and now is the best time to be thinking about applying a pre-emergence herbicide to control crabgrass.

To be successful in controlling the growth of crabgrass is to have a good understanding of its life cycle. Crabgrass is a summer annual that begins to grow in late winter to early spring (which is coming soon). Crabgrass, unlike most lawn weeds, grows from seed that the mother plant produced the previous summer. The mother plant flowers in the summer, then leave new seed on the ground and die completely with our first hard frost in the fall. In late winter / early spring this seed will germinate and start to grow. Thus, this is the lifecycle of this annual, grassy weed.

As I mentioned, it is now mid-February. Our weather in February can be fickle giving us lots of spring-like temperatures. If our soil temperature should reach 55 degrees for 2 or 3 days then crabgrass has the potential to begin germinating and growing. I checked my soil thermometer on the 14th and it is reading 42 degrees and rising. Hence, the reason I am writing this blog now and stressing the urgency to think about putting down a crabgrass pre-emergence NOW.

We have a unique indicator alerting us to put down our crabgrass pre-emergence and that is our blooming FORSYTHIA. You MUST have your crabgrass pre-emergence applied before the flowers have completely fallen off the forsythia. It is a convenient coincidence that crabgrass seeds germinate at the same time that forsythias are flowering. I have had numerous customers report seeing forsythia already in bloom.

You may be asking yourself why is Doug stressing putting down the crabgrass pre-emergence now in mid-February and not waiting until we see forsythia shrubs in bloom? I am suggesting now because our February weather can be fickle. Secondly, the standard pre-emergents have soil activity for 6 to 8 weeks. By applying it soon it ensures that you did not miss the appropriate application timing.

A few additional tidbit information:

  1. A thick, healthy turf is the best method of crabgrass control.  Crabgrass seed requires sunlight to germinate.  A dense turf canopy will reduce sunlight and thus help keep the annual crabgrass seed from growing.
  2. Remember, prevent crabgrass now but, wait to wage war on the broadleaf weeds.
  3. A second application of pre-emergent is suggested in May.
  4. Don’t think of adding any regular grass seed now.  The pre-emergent will keep fescue grass seed from germinating and growing as well.

HAPPY GARDENING IN FEBRUARY!!!

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13 thoughts on “GARDEN TIME with DOUG – Crabgrass, A Real Pain in the Grass!

  1. Certain pre emergent weed killers prevent seed germination for months. Depends on the product used. Just from experience, I have had little luck planting cool season grass seed in the spring in Virginia. Fall is the optimal time to sow this seed. The heat of the summer and weeds tend to kill the grass off. Just my experience. Good luck!

  2. Lisa,
    Thank you. Everything you state is correct. Any fescue, cool season grass seed put down in spring does not have enough time to grow a deep root system and struggles and dies during the heat of our summer. Everyone needs to keep in mind that we are talking the cool season fescue grass seed. Late spring, around May, is the start time with the warm season grass seed such as bermuda and zoyzia.

  3. Hi Doug, Thanks for this advice on getting ahead of the weeds sooner rather than later. You must have been reading my mind as I was wondering how much longer I should wait. I have forsythia so each time I see them about to bloom, I’ll think of your good advice.
    New question: Other than zoysia and bermuda, is there any SOD that I could put down in the spring that would actually survive our brutal summer?

  4. I have old fashioned orange daylilies growing around my roadside mailbox. I try to keep the grasses pulled out, but by the end of the summer they are too well established to simply pull. Should I use a pre-emergence herbicide on them? I don’t want to hurt the daylilies. Thanks for your advice.

  5. Sylvia,
    Thank you for reading our educational blogs. And, I am glad you find them helpful. Homeowners will be installing sod in March. The advantage of sod over seeding is that with sod the grass has an established root system. No question in that it will require timely watering to maintain through a hot summer. But, it can be done and done successfully.

  6. Margann,
    Thank you for reading our blogs and then taking the time to send us your question. Yes, you can use a combination of some new mulch and some Preen to help fight weed growth. I would suggest edging this area that is around your mailbox in order to cut away the grass. You don’t identify the grass. Is it wiregrass? If so, you could use a product called Grass B Gon or Over the top that should kill the grass and not hurt your daylilies. Doug

  7. I am converting my lawn to Bermuda and have applied my first round of pre emergent. Does Bermuda also require a second application in May?

  8. I never really knew the schedule for crabgrass so thanks a bunch for that info. I have an area on the side of my house that’s under a tree and is about 20’x30’. The soil is a mix of sand and just ugh, nothing seems to grow there. Lots of rocks, twigs and branches from the tree all the time. I’m wondering what I could throw down there that would grow. It doesn’t get much sun but does get filtered light. I live near Baltimore, Md. thanks.

  9. Jules,
    Glad that you have the pre-emergent down now. If you are converting your lawn from fescue to Bermuda then you want to begin this transition starting in May. We need to be warm and we need our soil temperature to warm up before you put down any bermuda grass seed. With this said, you can’t be seeding and using a pre-emergence at the same time period. Good luck. I hope your conversion is a success for you. Doug

  10. Karen,
    thank you for reading our blogs and then taking the time to send me your question. You have an area that is very similar to one that I have. What I finally ended up doing is spreading mulch on this area in order to give it a define look. Then I started adding a few boxwoods since then like the shade and are shallow rooted. And, I start adding some shade loving perennials to the area such as hosta, ferns, heuchura, etc. With each planting I amde sure to add some compost with each hole that I dug. Good luck. I hope it works out for you whatever you decide to do. Doug

  11. Thank you for your advice. I don’t know what the name of the grass is, but I’ll try Grass B Gon once the weather gets a little bit better.

  12. Thanks for the info Doug. In addition to stopping the crabgrass, here in Spotsy we had a lot of rain in the past year and moss has taken over one portion of my yard and is spreading. What’s the best way to remove moss and get grass to become vibrant in this area?

  13. Allen,
    I guess with all the rain last year it stands to reason why I have talked to so many customers about moss issues. So, you are not alone. All this rain has caused our soil to be more compacted than usual. Lawns need to be aerated in order to loosen this compaction and allow oxygen to get into the soil. This is the first step in controlling moss growth ( aeration ). Secondly, again with all this rain – it may have affected your pH level. Your soil may be too acidic – another reason for moss growth. Test the pH. If it is below 6.5 then I would recommend liming in order to “sweeten” the soil. Where you see heavy moss growth – you may want to try to “scrap” it up. Then sow some new grass seed in these bare spots. Good luck, Doug

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