weed explosion in my city backyard

Question: In October 2022 I had a lawn service (Organic Bob) prepare my small bare backyard (20x 20) and plant with fescue. Because so little sprouted, the lawn service returned on April 27 to "remediate": which involved spreading a thin layer of soil and re-seeding.  The fescue slowly sprouted, as I followed the watering instructions, but weeds grew faster.  I tried to weed, but got a late start for medical reasons, and was able to a first clearing of perhaps 2/3.  The rest is completely covered with weeds, and difficult at this point to remove by hand.  So I am wondering what to do.  I have replanted this lawn before, but never has there been such an explosion of weeds. The grass underneath the weeds is doing pretty well, and if I could just remove the weeds, I think the lawn would grow in nicely.  The first photo (5020) shows the unweeded part as of July 6.  The second photo shows the part I weeded two weeks ago, already growing back in.

responder: Barbara, Anoka County MG, TCA Replied July 06, 2023, 2:30 PM EDT
response: I would purchase a Broadleaf Weed Killer product.  It will not kill your grass but should take care of the weeds.   Do it now while the air is still cool because you do not want to do this on a 90 degree day.  It will vaporize and affect plants/shrubs you do not want to treat.  Read the label.  It should say For Lawns.  Will not kill grass.

responder: The Question Asker Replied July 06, 2023, 2:51 PM EDT
response: Thanks, Barbara, for the suggestion.  I should have pointed out that I am trying to have an organic lawn  (I live in a LEED Platinum, net zero house with native Minnesota plantings—if curious, google ‘Net Zero Victorian’ for more info on it).   ‘Organic Bob’ recommended Fiesta, (Iron HEPTA (?)). Are you familiar with this, and would you recommend it?  I had used it last summer and it took three or four applications to kill weeds between patio blocks.    Also, I am wondering about the kinds of weeds shown in the photos.  I wonder if they are a random set, or typical of any particular kind of meadow or planting strategy.  It just seems odd that so many should come up at once.  Have you seen this happen before—an explosion of weeds?   Thanks in advance.   Stewart Herman   From: ask=<personal data hidden> <ask=<personal data hidden>> On Behalf Of Ask Extension Sent: Thursday, July 6, 2023 1:30 PM To: Stewart Herman <<personal data hidden>> Subject: Re: weed explosion in my city backyard (#0109217)

responder: Barbara, Anoka County MG, TCA Replied July 06, 2023, 10:53 PM EDT
response: If you do a search for Fiesta, (Iron HEPTA) you will find that it is a herbicide, as are the broadleaf weed killers I recommended.  Disturbed soil will contain a multitude of weed seeds that now see sun and moisture.  The soil added on top of your lawn was scrapped up from somewhere and so does contain those seeds.  Your only choice will be to continue to pull weeds or use the herbicide.  Some people mistakenly try vinegar or some other homemade mixture which does more damage than the retail products.  Vinegar may kill the top of plants but not the roots but it changes the pH of your soil, sometimes making it almost sterile.  I am close to being organic in my vegetable and flower gardens and landscape.  However, there are situations where the right product, used the right way, is the answer.  Good luck.

responder: The Question Asker Replied July 06, 2023, 11:22 PM EDT
response: Thanks again, Barbara – I am wondering if Fiesta might go easier on the fescue than other broadleaf weed killers.  I don’t applying it as needed.  But I really don’t want to kill the fescue.   Stewart   From: ask=<personal data hidden> <ask=<personal data hidden>> On Behalf Of Ask Extension Sent: Thursday, July 6, 2023 9:54 PM To: Stewart Herman <<personal data hidden>> Subject: Re: weed explosion in my city backyard (#0109217)

responder: The Question Asker Replied July 07, 2023, 9:35 AM EDT
response: Barbara, did y ou recommend specific broadleaf herbicides, as your message implies?  I would welcome recommendations.  Thanks!

responder: Barbara, Anoka County MG, TCA Replied July 07, 2023, 12:38 PM EDT
response: We do not recommend specific brands.  I had suggested that you read the label of any product considered and that is must be labeled broadleaf weed killer and safe for lawns. That means it is safe for use on fescue as well as other lawn grasses.  I was able to download the label of Fiesta.  Please read it.  It does state you may have to make several applications.   The final decision is yours to make: file:///C:/Users/owner/Downloads/Fiesta_10L_booklet_6Oct21.pdf

responder: The Question Asker Replied July 07, 2023, 5:15 PM EDT
response: Thanks.  I just tried Fiesta, and it didn’t stick to 80% of the leaves—only to the really wide ones.  I really wish there were more practical information on your site about what it is like to actually work with the stuff.   Stewart   From: ask=<personal data hidden> <ask=<personal data hidden>> On Behalf Of Ask Extension Sent: Friday, July 7, 2023 11:39 AM To: Stewart Herman <<personal data hidden>> Subject: Re: weed explosion in my city backyard (#0109217)

responder: Barbara, Anoka County MG, TCA Replied July 07, 2023, 8:07 PM EDT
response: As I have told you, we do not recommend any product by brand name.  We have no information on Fiesta, only OTC  broadleaf weed killers for lawns as found in your local garden centers.  I had never heard of the product you used and had to search to find an informative label for you on line.  Sorry you still have weeds.