Welcome to the latest issue of the Home Lawn Care Newsletter from UMN Turfgrass Science! We will provide up-to-date information to address all your lawn care tasks at the times when you need to know.
April 15, 2024: Issue 20
Spring has sprung! Your lawn is greening up quickly, so we are here to help you make sure your 2024 growing season gets off to a great start.
Would dethatching help your lawn?
Thatch is a layer of decomposed or partially decomposed plant and soil organic matter between the living plants and the soil. Dethatching is the practice of mechanically raking a lawn to decrease thatch by physically removing it or increasing its decomposition via microbial activity. Excessive thatch can result in uneven mowing surfaces, lead to excessive moisture retention, and serves as a haven for some insect pests. Keeping thatch less than ½ inch thick is good for your lawn as it improves nutrient availability, air circulation, and water penetration; thatch can also reduce fluctuations in temperature.
There are some risks to dethatching, however. This practice stresses grass and can damage the root system and leaves of living plants, especially when it’s not timed properly; dethatching also exposes soil where weed seeds may be established.
A sharp knife can be used to cut a piece of sod to observe thatch thickness. More often than not, excessive thatch is not a problem in home lawns. If you have Kentucky bluegrass and you water and fertilize frequently, you’re more likely to have accumulated excessive thatch. For most lawns, you’re probably better off not dethatching, especially in the spring when summer annual weeds are germinating. Ideally, dethatching is done from late August through September to non-stressed turf. This allows for the lawn to recover prior to the winter.
Aeration is sometimes marketed as having dethatching benefits, but several research reports have shown this to not be the case. Aeration, which is best done in the fall, is most beneficial to relieve soil compaction, improving air circulation and water penetration into the soil.
How to control thatch in your lawn | UMN Extension
Lawn care calendar | UMN Extension
How to hire a lawn care company
With the last several years of challenging weather, a lot of turf has been lost or replaced by weeds. Hiring a lawn care company could help take a load off your shoulders and get your lawn back on track.
For some, hiring a lawn care company may be as simple as finding who provides the right services or the best value in the area. Others may be more inclined to align personal values with the company treating the lawn. The types of products used and services offered by companies can vary tremendously. Having an idea what your lawn might need can help narrow down the services necessary. Some companies emphasize sustainable and environmentally friendly lawn care practices. Organic and natural lawn care options are also widely available and growing in popularity. Many companies will offer free quotes as part of a promotion.
Here are some specific things to look for with a lawn care company:
- The company is willing to listen to your wants or needs prior to suggesting services
- They share specifically what they will be applying to your lawn or landscape
- They collect a soil sample from your lawn prior to applying fertilizers or chemicals
- If they are recommending seed, it matches your growing conditions and desired aesthetics
- The company has appropriate state and local licensure, and is both insured and bonded
- They have a chemical applicator’s license for fertilizers and pesticides
- They apply pesticides only when there is a documented pest outbreak
Third-party websites track reviews for lawn care companies and can be helpful for finding someone in your area that fits your needs.
How to submit soil samples for lawn and garden analysis | UMN
Selecting a lawn care service | Clemson Cooperative Extension
Selecting a lawn maintenance service | NC State Extension
Post-emergent crabgrass control
The fluctuating temperatures we’ve experienced this spring mean we will more than likely have a breakthrough of crabgrass and other summer annual weeds, regardless of if a pre-emergent herbicide was used. If you applied pre-emergent early this year, you may need to consider a second application later in spring to control through the summer. Crabgrass begins to germinate when soil temperatures are consistently between 55 and 70 degrees. At the time of publication of this newsletter, the entire state is still within the optimal range for applying a crabgrass pre-emergent according to the University of Minnesota Turfgrass Dashboard.
If you do find crabgrass emerging, rest assured there are many options for dealing with it this season with post-emergent herbicides. Post-emergent refers to the period where the seedling has emerged but before that seedling matures. Earlier intervention is better when the plants are small, and you may be able to spot spray if the crabgrass is not a problem in your entire lawn. Pay attention to the active ingredient of the herbicide - this will be listed on the product packaging.
- Dithiopyr is a unique herbicide that has both pre- and post-emergent abilities, but it can be less effective on older (more than one five leaves) crabgrass seedlings.
- Quinclorac is good for younger crabgrass and is also one of the better options for use on older crabgrass.
- Mesotrione and topramezone are newer post-emergent herbicides that have a wide age range of control for crabgrass plants, but like others, they gradually lose efficacy as the plants get more mature.
If you dormant seeded prior to or during winter, consider waiting until after the first mowing before treating the crabgrass seedlings so that the new turfgrass plants aren’t damaged by the herbicide.
Crabgrass | Purdue University
Controlling crabgrass after it emerges | Michigan State University Extension
Research highlight
One of the best ways to control crabgrass and other weeds is by maintaining a healthy lawn. A dense turf can keep out the weeds by shading the soil surface and outcompeting emerging weeds for water and nutrients. The fine fescues have been shown to suppress weeds better than many other lawn grasses. To read more about the research the University of Minnesota turfgrass science team has conducted on fine fescue weed suppression, check out these articles:
Can we control lawn weeds without herbicides? | UMN Turfgrass Science
Field evaluation of weed suppression in fine fescue (Festuca spp.) | Crop Science
Events
We will be at these events to answer questions on smart irrigation and lawn care as part of our collaboration with the Metropolitan Council.
- Watershed Cleanup Day and Earth Day Celebration in Lakeville, MN on Saturday, April 20, 2024 from 11:00 a.m. to 1:00 p.m.
- Environmental Fun Fair in Fridley, MN on Saturday, May 18, 2024 from 11:00 a.m. to 2:00 p.m.
- Trista Day in Minnetrista, MN on Saturday, May 18, 2024 from 11:00 a.m. to 2:00 p.m.
Have a question on a topic we didn’t cover in this email?
We have resources to answer your questions! Check out these options for even more lawn care information from the University of Minnesota.
We provide research updates, lawn care tips, info about field days, and more at @UMNTurf.