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Archive for the grass tag

Diagnosing and preventing brown spots in lawn

January 25, 2020   •   Leave a Comment

In my lawn, there are random brown spots about the size of a tennis ball or slightly larger. This condition only seems to happen during mid to late summer, nothing earlier. I fertilize about every six weeks and mow weekly, never cutting more than 1/3 of the grass blade. I don’t have pets, though there are plenty of squirrels and birds. I have a lawn irrigation system that I operate on designated days with about 20 minutes in each zone. What is causing the brown spots and how do I eliminate them?

What a great analysis of your lawn problem; it shows you pay attention to details in the management of your turf. It appears you have a fungal disease called “dollar spot,” so named because the sunken dead spots are about the size of a silver dollar. The spots are about 2 to 3 inches wide, and several spots may grow together, killing a larger area. The fungus can survive in an unseen dormant state in infected turf. When the daytime temperatures reach 60 to 80 degrees, it resumes growth and infects healthy grass blades. Dollar spot occurs when a combination of warm days and cool nights produce dew on the lawn in the morning, which was our mid to late summer pattern this year.

You are mowing exactly the right way. The fact you need to mow once a week says your lawn is actively growing and is probably receiving sufficient fertilizer to maintain nitrogen levels. Kentucky bluegrass, a cool-season grass, grows most vigorously in the cooler months of fall and spring. So, the most important time to feed it is in spring and fall. Feeding every six weeks as you are doing may be unnecessary.

For the best lawn appearance, Ron Calhoun at Michigan State University’s Turf Management Center recommends the “holiday program.” Make one full application about Memorial Day, a half-strength application around the 4th of July, a half-strength application around Labor Day, and one full application around Thanksgiving. Include the pre-emergents for crabgrass with the last one.

The key adjustment for you may be in the amount of water. Your irrigation system may be set to compensate for drought conditions. Try reducing the irrigation frequency and duration, and avoid watering in late afternoon and evening. The rate should be 1/10 inch per ten minutes. Water in mid-morning so that the grass has time to dry out before nightfall. Check the amount of thatch in your lawn. It could benefit from core aeration, a mechanical process that methodically punches holes in the turf and pulls tiny plugs of soil to the surface. Aerating does exactly what it sounds like: it increases air spaces for healthy root growth. If you want to reseed areas, look for resistant bluegrass varieties such as Adelphi, Eclipse, or Vantage. With minor changes and adjustments, you should see those dollar spots disappear from your lawn. 

Filed Under: Clippings Tagged With: brown spots, brown spots in lawn, diagnosing, grass

Growing grass under trees

June 18, 2019   •   Leave a Comment

Our yard is shaded by oaks. We overseed every year with shady grass mix. But by the next spring most of the grass has died. What can we do to grow grass in this situation?

You have a couple of choices. You can continue the frustrating cycle of growing grass, or take an alternative approach to living with your oaks. Turf grass needs sun to germinate and establish a root system, even if it is the “shady grass mix.” If your oak canopy is heavy and dense, you could have the canopy judiciously thinned by a trained arborist. They will prune when the trees are dormant in winter and there is little chance for them to be infected with the oak wilt disease. This might open up the canopy enough to let the turf lawn get established.

However, you should know that oak trees can take up to 50 gallons or more of water a day. So while you are watering that lawn you’ve overseeded, the oak trees with their extensive root systems are enjoying the feast. The turf grass never gets its root system established because the oaks are not only shading it out, but also absorbing most of the water.

This is not necessarily a bad thing. Oak trees are preferable bastions of shade. The alternative is to try a different groundcover that isn’t lawn. Oak trees create dry shade. It sounds like your lawn is fairly thin underneath them, which is why you keep overseeding every year. Why not plant dry shade-loving perennials? There are a number of low maintenance plants that would not only lend interest to the landscape under the oak trees, but are low profile, will come up every year, will succeed where turf grass fails, and will provide “green coverage” that you don’t even have to mow.

Consider a mass planting of variegated hostas that would “light up” the shady area under the canopy. Another perennial often used where grass is unsuccessful is lily turf (Liriope spicata). It even looks like grass, but has the bonus of a purple-blue flower in summer, which turns to a red-brown berry in fall. At the outer edge or drip line of the canopy, you could mass plant Stella d’Oro daylilies. They tolerate a wide range of soil types and light conditions. Their yellow blooms are continuously cheerful and when finally done blooming, their foliage lasts until frost. A simple ground-hugging vine is vinca, sometimes called myrtle. It produces a lovely blue flower in spring that shows well in heavy shade. There is also the nice spotted dead nettle (Lamium maculatum) with its silver and green mottled leaves. The cultivar ‘White Nancy’ produces a lovely white flower while other varieties produce pink blossoms mid-spring.

So there are several alternatives and choices to groundcovers that aren’t turf grasses. You need to decide where to put your money: into perennials that will succeed in the shade of your mighty oaks, or continue trying to grow turf grass that will always struggle.

Filed Under: Ask MG Tagged With: grass, growing grass, oaks, shade, trees

Janet’s Journal: Lawn Long Gone

August 31, 2018   •   4 Comments

Nothing looks so good alongside a flower bed or feels so comfortable underfoot as lawn. It deserves better than we give it. After years of drought and neglect, your lawn might need your care more than a quick pass with a magic wand dispensing liquid fertilizer and weedkiller.
Nothing looks so good alongside a flower bed or feels so comfortable underfoot as lawn. It deserves better than we give it. After years of drought and neglect, your lawn might need your care more than a quick pass with a magic wand dispensing liquid fertilizer and weedkiller.

How to restore weed-infested lawn areas to healthy turf grass

My mailbox is full! One out of four letters reads: “My lawn is being taken over by (description or sample of weed). I’ve tried weedkiller but it didn’t work. What should I do?”

News flash: In many cases, the weeds are not taking over your lawn. They are your lawn. Perhaps you should think twice about trying to kill them.

The grass has been dying out for years, thinned by drought, heat and wildly oscillating winter temperatures over snowless, uninsulated turf. It’s tempting to think that a few passes with the right magic wand will fix it, but it won’t happen that way.

Portrait of a dying lawn

Five years ago, your sod may have had a dozen bundled grass blades in each square inch, the individual growing points snuggled tight against one another. Those leafy sprays were content to be packed in with their fellows since they were all equals—and polite, as plants go. They were also healthy, each one tapped into enough water and nutrients to meet its needs.

Then as soil moisture dwindled, these plants began to strain. Whenever temperatures soared you could almost hear them wheeze, as their pores closed in defense against dehydration. Although those pores release water vapor and have to be stopped like leaks when heat and drought combine, they also serve as intake ports for atmospheric gases. Without those gases that are essential ingredients in photosynthesis, the whole sunlight-into-sugar process stops. The plant must switch to emergency power—burning the starch stored in its roots. This literally reduces the size of the roots. As they shrink, so does their reach. They cover a smaller, shallower area so the plant has even less moisture to live on.

One by one, the grass blades sicken and die from starvation, dehydration or diseases they were once vigorous enough to stave off. In the new open spaces, sun penetrates and dark soil absorbs the radiation, heating and stressing the roots further.

The advent of rude, greedy weeds

Meanwhile, the sun has now reached and spurred the germination of heat-loving seeds such as crabgrass that can wait decades for such an opportunity.

These newcomers to the grassy carpet are not polite. Crabgrass is all elbows and explosive growth. Spurge, purslane, ground ivy and others don’t even have the manners to stand up straight. They sprawl and worm their way between grass blades. All of them are better able to function in hot, dry times and compete heavily with the sickly turf for available water. Thieves like dandelion and Queen Anne’s lace put all their seedling energy into deep tap roots that drain the lower reaches of the soil.

News flash—those weeds aren’t taking over your lawn, they are your lawn!
News flash—those weeds aren’t taking over your lawn, they are your lawn!

At first it’s just a few discolored spots in the lawn where weeds have incurred. If you return the lawn to good health you can keep it at this state of nearly all lawn or even reverse the tide.
At first it’s just a few discolored spots in the lawn where weeds have incurred. If you return the lawn to good health you can keep it at this state of nearly all lawn or even reverse the tide.

In their first year of lawn incursion, maroon-tinged, clover-like oxalis plants (common yellow sorrel) can be overlooked as nothing more than slightly discolored areas of turf. Yet these weeds have dropped seeds and runners into every available space. Given continued poor growing conditions for grass and inadequate lawn care by the gardener, they will run amuck in subsequent years.
In their first year of lawn incursion, maroon-tinged, clover-like oxalis plants (common yellow sorrel) can be overlooked as nothing more than slightly discolored areas of turf. Yet these weeds have dropped seeds and runners into every available space. Given continued poor growing conditions for grass and inadequate lawn care by the gardener, they will run amuck in subsequent years.

Creeping along beneath our notice

In its first year, all this trouble may escape our notice. It’s a few discolored areas of maroon-tinged, clover-like oxalis, chartreuse nutsedge or gray-green henbit. Those pioneers make lots of seed, however. They also crowd and shade out more lawn. By seed and runner they move quickly into every new opening.

Winter kill leaves even more gaps in the sod, just in time for cool season weeds such as chickweed and creeping speedwell to sprout and settle in. Since they germinate between November and March, the gardener spreading grass seed in April is too late, and her well-intentioned fertilizer assists the wrong plants.

After years of escalating losses, we finally notice the trouble. Restoring that battered greensward now is more a matter of starting over than kicking out a few weeds.

Crabgrass is all elbows and explosive growth, and produces seeds that can fill an empty space next year or lay in wait for twenty! Ground ivy doesn’t even have the manners to stand up straight. It sprawls and worms its way between grass blades. Dandelions have a deep tap root that pulls the water down away from the shallower grass roots.
Ground ivy doesn’t even have the manners to stand up straight. It sprawls and worms its way between grass blades.

Fix the areas where poor drainage has been undermining your lawn’s health.
Fix the areas where poor drainage has been undermining your lawn’s health.

Starting over

It’s best to sow seed between the third week of August and the middle of September when conditions are prime. Fall rains and milder temperatures support seed germination and establishment.

You’ll need broadleaf weedkiller since handweeding thousands of square feet that’s mostly weeds is usually not practical. Don’t use preemergent, though, if you intend to sow grass seed.

If there is almost no grass left in that field mowed short you’ve been calling “lawn,” kill the whole shebang with a non-selective herbicide such as glyphosate. Whichever route you take, time it so the herbicide finishes its work before the prime time window for sowing closes.

Oh, but you said that weedkiller didn’t work. With no offense intended, I think that was not the fault of the herbicide. You may have applied it when it couldn’t work, such as in the hottest part of summer when the target weeds were metabolizing too slowly to be affected. Or perhaps you spread a weedkiller over dry greens. Rather than sticking where they could do the most harm, the pellets slid to the soil and dissolved with little effect. Maybe you did kill some weeds, but without follow-up help your lawn couldn’t recolonize the weeded spots. By the time you looked again, the bad guys had reasserted themselves.

Don’t spread seed on dead weeds. Rake or till to let the seed fall on loosened soil, as shown here.
Don’t spread seed on dead weeds. Rake or till to let the seed fall on loosened soil, as shown here.

Seeding like you mean it

After killing the weeds you’ll need grass seed. Buy a premium blend—bluegrass for sun, fescue for partly shaded areas. “Premium” is an important term. It means the seeds are from recently developed strains of grass bred for disease resistance. In a lawn as ravaged as yours, disease organisms have found a toehold and could devastate susceptible seedlings.

You can sod rather than seed. But sod is more expensive than seed, while both are quick to take in September.

Don’t spread seed on top of dead weeds. Seed must rest on moist soil to sprout and survive. Till lightly, make numerous passes with a core aerator, work the soil with an iron garden rake—whatever it takes to loosen and expose the earth. Smooth it and water it so it’s settled, moist and level like a tray of potting mix ready for seeding.

While you’re at it, address other problems that have undermined the health of your turf. Level or drain puddled and soggy areas. Use a garden fork to pierce and break up the compacted layer that’s been there, 6 to 9 inches down.

If a hard pan exists all over your property, you could rent an irrigation pipe-pulling tractor and drive it back and forth with its pipe slitter lowered but no pipe being played out. This will knife into or through that dense, airless, water- and root-stopping layer so soil dwelling creatures can finally move in and soften it.

Rake lightly after seeding to tumble the seeds with soil crumbs at the surface. No straw cover is necessary—sod farms don’t mulch! Don’t water right away. Wait for Nature to do her thing. Fall rains will coax the grass up and keep it growing. Water only if Nature fails you and the soil begins to dry after the seed has sprouted.

Take it from there

Fertilize when the new grass is 1-1/2 inches tall. Mow when it reaches 3 to 4 inches, just barely clipping its tips with a freshly-sharpened blade—dull blades can uproot the seedlings. Most important, get down on your knees to watch for weeds, then kill or pluck them as they appear.

While you’re down there, apologize to your lawn and promise to water often, lightly—so the water isn’t wasted below summer-shortened lawn roots—at midday when it’s hot so the mist cools the air and pores can stay open.

These directions may sound like heresy but have been proven effective by tests at Michigan State and other universities. “Water deep and infrequently” sounded good but had not been empirically tested before 1995 and turned out to be inappropriate for lawn species.

Tell it you’ll mow it high so it has enough body to shade out weeds and cool its own roots. Mean it when you say you’ll fertilize at the start and end of each year with a slow-release, soil-building organic fertilizer.

Finally, promise that you’ll pay closer attention from now on, so problems won’t get so out of hand.

Or take it in another direction

Reviving a lawn isn’t your cup of tea? I can sympathize. Lawn care bores and frustrates me—millions of clones demanding my help to grow evenly across sites where soil conditions, sun and moisture vary foot by foot. Yet I respect its place in the landscape and all the work that’s gone into breeding grasses and developing lawn care products that work even in our clumsy hands and laughable sites. Try as long and hard as you like, you won’t find another plant so visually perfect as edging for flower beds, that we can grow with so little care yet walk on regularly, enjoy in all four seasons and depend on for decades of service. Like me, you’d better learn to care for it correctly.

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

Filed Under: Janet’s Journal Tagged With: Fertilizer, grass, Janet Macunovich, Janet’s Journal, lawn, organic, turf

What is the difference between a “cool season” grass and a “warm season” grass?

August 1, 2011   •   

Warm season grasses typically grow actively in the spring and summer, will generally have attractive coloring in the fall, and will go dormant in the winter. Cool season grass experiences it’s period of active growth in the late winter or early spring. They will bloom in the early part of the summer, and then enter a period of dormancy or slow growth later in the summer into the fall. A number of grasses of this type are evergreen.

Filed Under: Ask MG Tagged With: cool season, grass, grasses, warm season

What is the best time of year to reseed bare patches in the lawn?

July 8, 2011   •   

What is the best time of year to reseed bare patches in the lawn? Can it be done in the spring? If so, please provide tips.

In Michigan, late August to mid-September is the ideal time to seed all grass types. The soil is warm yet the air has cooled down from summer temperatures.

However, most homeowners don’t want to go through the summer with a spotty lawn. Mid to late spring can be a suitable time to reseed bare patches in the lawn, after frost warnings are lifted. The soil temperature needs to be at least 50 degrees for grass to germinate at a normal rate. Waiting longer gives the soil more time to warm up to about 60 degrees and improves your success rate. Given sufficient moisture, the seed will germinate quicker with the added warmth, depending on the seed type.

Do not apply any spring lawn weed killers or crabgrass preventers. If you do, grass seed will not sprout or the seedlings will be killed along with the weeds and crabgrass.

Prepare the patches by removing any weeds. Scratch up the soil with a heavy dirt rake or cultivator. Mix up 1/3 sphagnum peat moss with 2/3 good garden soil to get a light, spongy texture. Add 1-1/2 cups of balanced organic fertilizer per bushel of soil making sure the fertilizer has a high phosphorous (P) content to stimulate root growth. Most “starter fertilizers” are high in phosphorous. Spread this mixture over the bare spot until it is slightly higher than the surrounding soil level. Gently work it into the scratched-up soil originally there.

Use a seed type similar to the existing grass unless it was the wrong kind to start with. Buy new seed. The percentage of seed that will germinate from old seed drops drastically with each year. Also avoid bargain seed. They generally contain the largest amount of annual or rough-bladed grasses.

Hand cast your seed and don’t be stingy. About 15 to 20 seeds per square inch is good. Bury the seed 1/8 to 1/4 inch into the soil by dragging a spring rake over the area with the tines inverted. Do not tamp so hard that you compact the soil. You want water to soak in easily. It is also helpful to cast some of the new seed to the outside of the repaired spot. This helps the new grass blend into the neighborhood!

Grass seed needs both moisture and warmth in order to sprout. Cooler temps will make it germinate slowly. But if there is a lack of moisture it won’t do a thing. Once the seed has germinated, avoid walking on the repaired spots to give the new plant roots time to dig in and acclimate. If you seed with a blended mix, the different types will germinate at different rates. So when you see green sprouts, continue to provide water for the later varieties to germinate.

Related: Keeping your lawn green

Filed Under: Ask MG Tagged With: germinate, grass, lawn, reseed, spring

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