Plant Turf Seed or Control Weeds First?

A common question this time of year is whether to plant turf seed now and control weeds later OR to instead control the weeds now and then seed later. Here are my thoughts.

Cool-season turf seed mixture.

Option 1 for areas with mainly broadleaf weeds and a few annual grasses: Plant now and control weeds later.
The optimum time to control perennial broadleaves and germinating winter annual broadleaves is in October. As such, seeding in late August and early September should allow enough time for seeds to germinate, grow, and be mown twice (assuming you irrigate and fertilize these newly seeded areas) prior to an October herbicide application. You can delay the herbicide application until late October and early November if you get a late start on seeding or if your seedlings are slow to establish (like Kentucky bluegrass). Most broadleaf herbicide labels suggests delaying application until newly seeded areas have been mown twice. Some herbicide labels allow a shorter interval between seeding and an application. These shorter interval herbicides include Quicksilver, SquareOne, and Drive (shorter interval tall fescue compared to perennial ryegrass and Kentucky bluegrass).

Typical language about postemergence herbicide application delays after seeding turf.

Drive XLR8 label instructions regarding application timing and seed and seedling emergence.

Option 2 for areas where you have lots of weed competition: Spray weeds now and seed tomorrow.
When there is a lot of crabgrass or broadleaf weed cover, then you would likely benefit from spraying the weeds now and seeding afterwards. Tenacity, Pylex, and SquareOne, and Drive are among the herbicides that can be applied today and allow seeding as soon as tomorrow (after the herbicide has had a chance to translocate in the target weed). Once the turf germinates, then follow the guidelines in option 1 above to provide follow-up weed control if needed.

SquareOne application instructions allowing seeding one day following the herbicide application.

Option 3 for areas perennial grassy weed competition: Spray weeds now and seed later.
When there are a lot of perennial grassy weeds such as quackgrass, fountain grass, etc., then your best bet to remove these perennial grasses before you seed as there are few herbicide options afterwards.
Best results with a non-selective herbicide like glyphosate are seen on perennial grassy weeds when multiple applications are made. Ideally, you would have started this process several weeks ago. Why? It is not uncommon for the weed to regrow from stolons or rhizomes (if a spreading grass) a few weeks after the first glyphosate application. One must allow the weed to regrow (wait at least three weeks) before the next application. At least two applications are recommended, but three or more may be needed. One must realize that the area will be dead and unsightly for a number of weeks or months if optimum control is desired.

Starting this process now, means that you won’t be able to seed until after the optimum seeding window of August 15 to September 15. If you are still committed to renovating this year, another seeding option is to seed in December through March as a dormant seeding after you have finished killing your perennial grassy weeds. Learn more about dormant seeding by clicking here.

If there are only a small number of patches, spot applications can be made with glyphosate. Reseeding can take place a day or two following final herbicide application. Once the area has been infested with a large number of patches, killing the entire area will be most effective with multiple applications of glyphosate. Renovation can begin five to seven days following final glyphosate application. Refer to AY-13, “Lawn Improvement Programs” for information on reestablishment.

One caveat to the above, Option 3 recommendation, is that we have a few selective herbicides for perennial grassy weed control that might be options for use during turf renovation.

Table 1. Non-selective and selective herbicide options for controlling perennial grassy weeds in cool-season turf.

Weed in cool-season turf
Non-selective herbicide option Selective herbicide option
Bermudagrass glyphosate Pylex (topramezone), Acclaim Extra (fenoxaprop)
Creeping bentgrass glyphosate Tenacity (mesotrione)
Dallisgrass glyphosate No effective selective control
Field paspalum glyphosate No effective selective control
Fountain grass glyphosate Drive (quinclorac) and other quinclorac containing herbicides
Nimblewill glyphosate Tenacity (mesotrione), Pylex (topramezone)
Orchardgrass glyphosate No effective selective control
Quackgrass glyphosate No effective selective control
Rough bluegrass glyphosate Velocity (bispyribac-sodium) for golf courses and sod farms.
Tall fescue glyphosate No effective selective control, formerly Corsair (chlorsulfuron)
Windmillgrass glyphosate Tenacity (mesotrione)
Zoysiagrass glyphosate Pylex (topramezone)(based on preliminary results following labeled instructions for bermudagrass control)

With any of these options, it is especially important to read the herbicide label and understand the application restrictions both before and after seeding and other application instructions (such as adjuvant and timing recommendations) so that you can maximize weed control and maximize turfgrass establishment.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

Aaron Patton, Turfgrass Extension Specialist
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Fescue. You mean there’s more than one kind?

Typical conversation about fescues.

Bill: What kind of grass do you have?
Bob: Fescue.
Bill: What kind of fescue?
Bob: You mean there’s more than one kind?
Bill: Yes.

As I travel around the region and give presentations or respond to email and phone questions, it is very common for me to enter into a dialogue with a person about planting, maintaining, controlling, etc. some kind of fescue. Usually in my interactions with people, they are unaware that there are many different kinds of fescues.

Festuca is the genus (first word in scientific name) for fescue species. Hence, Festuca’s are name Fescue. However, recently tall and meadow fescue were reclassified by scientists into the genus Schedonorus (see table below) although they still retain their same common name of fescue. Tall fescue and meadow fescue are similar with meadow fescue being used sparingly for overseeding in warm-season turf or as a forage grass and tall fescue commonly being used in lawns, roadsides and pastures. The remaining fescues including slender creeping red fescue, strong creeping red fescue, Chewings fescue, sheep fescue, blue fescue, and hard fescue are often grouped together and called “fine fescues” because of their narrow (fine) leaves. Another reason for grouping them all together is because they are difficult to distinguish from one another. Blue fescue is another fine fescue species used as an ornamental landscape grass.

Below is a breakdown of the common (and a few not so common) fescues used in turf (and ornamentals) and a short description of each.

Table 1. Description of the common and uncommon fescues used in turf (and ornamentals).

Common name
Species Comments
Slender creeping red fescue Festuca rubra ssp. littoralis Similar to strong creeping red fescue but with shorter, more slender rhizomes. Both slender and strong creeping red fescue tolerate some close mowing.
Strong creeping red fescue Festuca rubra ssp. rubra Strong creeping red fescue has more rhizome growth (spreading ability) than slender creeping red fescue. Strong creeping red fescue is a common ingredient in “Sun & Shade” mixes because of its good shade tolerance and its suitability in seed mixtures.
Chewings fescue Festuca rubra spp. fallax Named after George Chewings. Excellent shade tolerance and turf density, this fine fescue is similar to creeping red fescue but it lacks rhizomes.
Tall fescue Schedonorus arundinaceus (Schreb.) Dumort. (also = Lolium arundinaceum (Schreb.) S.J. Darbyshire; formerly = Festuca arundinacea Schreb.) Improvements in tall fescue have transformed this grass from a forage type grass to many improved turf-type cultivars. Today, both "forage" and "turf-type" tall fescue are used. Kentucky-31 (KY-31) is a forage type and not a lawn type. Known for its ability to maintain green color during moderate droughts due to its deep root system, tall fescue is more commonly used today on lawns than in the past.
Sheep fescue Festuca ovina Excellent drought tolerance. This fine fescue with fair turf density does not tolerate close mowing. It is often used in unmown, “native” areas of golf courses.
Blue fescue Festuca glauca Ornamental grass. Common variety is ‘Elijah blue’
Meadow fescue Schedonorus pratensis (Huds.) P. Beauv. (formerly Festuca pratensis Huds.) Similar in appearance to tall fescue. Little current use in high value turf.
Hard fescue Festuca brevipilla Excellent shade tolerance, this fine fescue does not tolerate close mowing. It is often used in unmown, “native” areas of golf courses.
Red fescue Festuca rubra Today, red fescue is classified into two groups: 1) Slender creeping red fescue or 2) Strong creeping red fescue. However, some seed labels may still just say, red fescue.

Figure 1. Unmown, fine-fescue used on a golf course. These areas are often described as no-mow, native areas, or environmentally sensitive areas to the golfers.

Figure 2. Chewings fescue. Notice the fine leaf texture (narrow leaf width) compared to tall fescue below.
Figure 3. Tall fescue (turf-type).

Aaron Patton, Turfgrass Extension Specialist

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Start Seeding Cool-Season Turf Now

The best time to seed a cool-season lawn is in the late summer to early fall. Adequate soil moisture, warm soil, and limited weed pressure allow for excellent seedling growth. Normally, we recommend seeding between August 15 and September 15 as the optimum seeding window. However, due to our cool summer and a relatively cool forecast for August, we are recommending that you can start seeding anytime now and there is no need to wait until mid-August.

It is critical to seed as early as possible within this window. Even when seeding within this window, waiting one week later to seed may mean the turf will take 2 more weeks to mature as germination and subsequent growth slows later in the fall as temperatures cool. Additionally, annual bluegrass and other winter annual weeds will be more problematic with fall seeding dates than late summer seeding dates.

Seeding early (later summer) allows the turf to maximize its establishment and rooting prior to the next summer's heat and drought.

For more information about establishment, see:

Aaron Patton, Turfgrass Extension Specialist
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Watering Newly Seeded Areas

Water is necessary to initiate the germination process in seeds. As the seed imbibes water, enzymatic reactions within the seed trigger the germination process. Enzymes breakdown the energy stored inside the seed endosperm and this energy is used by the seed embryo for growth. The first visible step in the germination process is the emergence of the radicle (this is the first root)(Figure 1). Next, the coleoptile (an opaque protective sheath) emerges. The coleoptile functions to protect the emerging leaf. Lastly, the green color of the first leaf can be seen as it emerges through the coleoptile. Once the first green leaf emerges, the plant can begin to make its own energy through photosynthesis and it no longer relies on the energy that was stored in the endosperm.

Figure 1. Pictured left to right in the order of the germination process are a newly planted seed, a seed with the radicle emerging, the coleoptile emerging, the leaf emerging through the coleoptile, and the leaf and root elongating.

Once the first irrigation or rainfall occurs after seeding, it is important to keep watering! Seedlings are very susceptible to moisture stress during the first few weeks after seeding (Figure 2). The upper 1 inch of soil should be kept moist with frequent irrigation for the first two or three weeks after planting. Germination will occur in 5 to 14 days depending on the temperature and the species planted (Figure 3).

Figure 2. Tall fescue seedlings emerging in a hydroseeded area. As new seedlings germinate they need to be watered frequently enough to avoid drying.

Figure 3. Pictured left to right in the order of germination are perennial ryegrass (PR), tall fescue (TF), creeping red fescue (CRF), and Kentucky bluegrass (KBG). This photo was taken six days after planting. NOTE: Kentucky bluegrass has not yet germinated in this photo.
After the seed germinates and seedlings develop roots into the soil, the lawn can be watered less often. Once established, the lawn should be watered deeply and infrequently only when the plant shows signs of water stress.

Aaron Patton, Turfgrass Extension Specialist
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