Two cases were identified in Missouri, and one each in Florida, Illinois, South Dakota, Utah and Wisconsin, the Centers for Disease Control and Prevention said.

People got sick in February and March of this year, the CDC said. They all had the same strain of salmonella — a version that has been traced to hatcheries in the past. The investigation is continuing, health officials said.

Salmonella bacteria cause about 1.35 million infections in the United States every year, and recent outbreaks have been tied to sources such as cucumbers, eggs, unpasteurized milk, fresh basil, geckos and pet bearded dragons.

But one concern is that chickens and other backyard poultry can carry salmonella bacteria even if they look healthy and clean. A backyard poultry-associated outbreak that ended last year was tied to 470 cases spread across 48 states, including one death.

Sponsored by the Clarendon Hills Chamber of Commerce, spent its first four years after starting up in 2017 in the Sloan Triangle at Prospect and Park Avenues. It moved in 2021 to Village Hall Plaza.

“Every year our neighbors look forward to the return of the Farmers Market, which signals the end of the school year, while continuing the village tradition of gathering and shopping together on Thursday mornings,” said Shannon McDonald, the chamber’s director. “We are really pleased to welcome back many of our returning vendors as community favorites.”

One vendor that isn’t returning is LaVanway Farms, out of Berrien Center, Michigan, which had been an anchor at the Clarendon Hills Farmers Market since its first year.

“Cindy with Lavanaway Farm has said she is stepping away from her involvement with markets and has been working since last year to pass the baton on to a nearby farm, Dad’s Farm, to take over her established farmers markets,” McDonald said.

Joining Dad’s Farm as a vendor new to Clarendon Hills are Flock and Field, offering personal care products, and Pet Wants, which will be selling pet treats and food.

Eleven vendors are scheduled to be onsite in Clarendon Hills throughout the season, including popular returnee Hahn’s Bakery out of Geneva, which has become well known in the village for its doughnuts, but has several other bakery items for sale.

Also returning are Azteca Catering Co. with Mexican cuisine, Spartan Gourmet Foods featuring olives and olive oil, Hufendick Farm Market with fresh pork, beef, poultry and lamb, Maly’s Foods featuring vegetable egg rolls, The Cheese Lady, Lincoln Land Kettle Corn and Boa Acai Bowls.

Little Love Tees, featuring children’s clothing, is scheduled to be in Clarendon Hills June 5 and June 26, and a new village business, Sparrow Coffee, will be joining the market periodically, McDonald said.

She said new vendors are added each year in one of two ways.

“Vendors come to us through word of mouth, and I will seek out vendors to help us fill a void in the market, offering consumable products,” McDonald said.

Along with the vendors, the Clarendon Hills Public Library will be hosting Children’s Story Time at 11:30 a.m. at the market on the second Thursday of each month— June 12, July 10, Aug. 7, Sept. 11, and Oct. 9.

Village President Eric Tech said he believes the farmers market provides a real sense of community and a gathering place for Clarendon Hills residents.

“For my wife, it is a ritual which she looks forward to, meeting neighbors and reconnecting with the vendors,” he said. “With the creation of the functional plaza in front of our village hall, it has the added benefit of drawing from our neighboring communities and showcasing our beautiful public spaces.”

Chuck Fieldman is a freelance reporter for Pioneer Press. 

It was, as he called it, a turning point.

“That was about four years ago, when I had 2,000 plants started,” he recalled. “When they were really small they weren’t a problem. But when I had to up-plant them into 4-inch pots, we had them in every room in the house, next to every window I could find.

“My wife put her foot down and said you can’t do that anymore.”

Zeni began his tomato deep dive several years earlier when seeking a late-winter distraction after years of working at home as a graphic designer.

“It gets cold in the winter and I wouldn’t leave the house for weeks,” he said. “My wife claimed I was getting weird, and she insisted that I get a hobby.”

At the same time he was reflecting on the “tasteless atrocities that pose as tomatoes at supermarkets” during the offseason and decided to do something about it. He set up some tables and lights and planted some seeds.

There were mistakes — “overwatering, under watering, not enough heat,” Zeni said. But along with those setbacks were “small successes that gave me enough hope that I was on the right track.”

After a few seasons, he had enough plants that he would give them to any and all interested neighbors, and his tomato operation in La Grange Park kept growing larger. He began selling seedlings at “garage sales” to help fund his hobby, selling 50 to 75 plants.

“We put signage up when people just started showing up, telling me they’d heard about me from other people,” he said. “I got to 500 plants and sold them out. I’d get emails in January asking when’s the sale? That was the first indication I got that maybe this could be more than just a wintertime hobby.”

He decided to go all-in and started calling himself the Chicago Tomato Man.

“It’s spiraled to the point where this year we’ll grow around 15,000 plants,” he said in April.

He still grows at home, but the bulk of his operation is offsite, using contracters who deliver his plants to a warehouse near Western and Ogden avenues in Chicago, where they’re matched to orders and taken to pop-up markets throughout the city and suburbs.

Some of those seedlings are earmarked for other purposes as well.

“We give away lots of plants,” Zeni said. “We hear about efforts by nonprofit organizations or groups that are running gardens that use their harvest to give away produce to food banks. We totally support those efforts, so we give them plants every year.”

Last year, the Chicago Tomato Man organization gave away nearly 1,500 plants, and they’re looking to equal that this year.

Among the organizations that have worked with Zeni is Eden Greens Urban Farm, which provides healthy food as well as gardening resources for underserved communities such as Pullman, Englewood and Greater Grand Crossing.

Tomato plants also went to We Grow We Sow, Inc., an urban farm based in West Pullman that offers produce and education to people in Roseland, Morgan Park and Calumet Park.

Seedlings have even gone to the Cook County Juvenile Temporary Detention Center, for its Karma Garden project.

“This is good,” Zeni said. “We want to get these plants to any neighborhood that lacks access to food.”

And they’re not getting run-of-the-mill tomatoes. They’re getting the good ones, the heirlooms, some that have been passed down seed by seed for generations of gardeners.

Among Zeni’s seedlings are varieties such as Rutgers, developed in 1928 by the Campbell Soup Company and released to farmers in 1934 by Rutgers University.

There’s also Mortgage Lifter, a large beefsteak tomato developed, as the story goes, in the 1940s by a gardener in West Virginia who crossed varieties for six years before arriving at one so popular he was able to pay off his $6,000 mortgage by selling plants for $1 each.

There’s several varieties, such as the Sandburg yellow, attributed to Millard Murdock, a gardener based farther south in the Blue Ridge Mountains, whose retirement efforts to preserve and promote heirloom tomatoes became legendary in the seed saving community prior to his death in 2019.

Closer to home, fellow legendary seed savers Merlyn and Mary Ann Niedens, whose tomato and sunflower patches were sown in downstate Okawville, are represented by varieties such as Illini Star and Illini Gold. According to his 2009 obituary, Merlyn Niedens acquired at least some of his tomato breeding know-how in River Forest with a bachelor of science degree from Concordia Teacher’s College, now Concordia University.

One variety Zeni just started growing this year is steeped in Chicago history. The Inciardi (pronounced in-chi-ardi) paste tomato was brought over from Sicily by immigrant Enrico Inciardi, who sewed the seeds from his family’s signature tomato into the lining of his jacket because he was afraid they would be taken from him at Ellis Island, Zeni said.

Inciardi ended up settling in Downers Grove, got a job at the Western Electric Hawthorne Works in Cicero and later attended a company excursion aboard the S.S. Eastland in 1915, surviving the worst marine disaster in Chicago history after the ship overturned in the Chicago River, killing hundreds.

Through it all, he kept growing his family’s signature Sicilian tomatoes.

“Now his descendants started offering them for sale commercially,” Zeni said. “That’s a great story.”

Zeni is helping preserve another family story thanks to an encounter with an older guy he met at one of his pop-up sales at the Percolator Coffee Shop in Portage Park. He showed Zeni some seeds and said, “My father-in-law brought these over from Calabria and has been growing them ever since. He passed away and we continued to save these seeds, and I want to give them to you.”

Zeni asked the man, who came out from River Grove, what the tomatoes were called.

“I don’t know,” was the response. “It’s always just been my father-in-law’s tomato. My family has been growing them for 100 years. I’ve been growing them in my backyard.”

The man’s name was Art Zaino, “so that’s what we called them,” Zeni said. “These are big tomatoes. They’re like 16-inch softball sized tomatoes.”

While the Inciardi tomato has become somewhat more well-known among heirloom aficionados, the Art Zaino is “something that’s exclusive to us,” Zeni said. “I don’t think he gave the seeds to anyone else.”

For Zeni, heirloom tomatoes offer not only the opportunity to share the stories of fellow nightshade aficionados past and present, but also some of the places where he sells seedlings as well.

He’s already kicked off the gardening season with popup sales around the city and suburbs, including Pollyanna Brewing in Lemont, and has more coming up. There’s one from 10 a.m. to noon on May 31 at Two-Mile Coffee Bar, 9907 S. Walden Parkway, near the Metra stop in Chicago’s Beverly community; and another from 1 to 3 p.m. on May 31 at the Hyde Park Neighborhood Club, 5480 S. Kenwood Ave. in Chicago.

He’ll be at Skokie’s Sketchbook Brewing, 4901 Main St., on May 25. Other Pollyanna locations will be on June 7 in Roselle and later that day in St. Charles.

Also on the schedule is the last of four pop-ups on May 24 at First Presbyterian Church of La Grange, 150 S. Ashland Ave. A full list as well as ordering information is on his website at chicagotomatoman.com.

“These are locally owned places that let us set up, and in exchange we try to recognize and promote them, encourage people to buy a croissant and a coffee, or a four-pack or growler of beer,” Zeni said. “It’s about creating community and helping community, so we all prosper and thrive.”

But his primary goal remains to spread his love of tomatoes.

“I understand why the food industry has done what they’ve done to tomatoes,” he said. “Everyone wants to buy tomatoes in January at the grocery store, so they’ve bred them so they’re durable, they look great and they’re all the same size. But the flavor is gone and I think it’s criminal.

“A real tomato is something everyone should experience. The flavor is so wonderful. It’s so gratifying when someone picks those first few off the vine and realize the experience was worth all the time and effort put in to grow them.”

Landmarks is a column by Paul Eisenberg exploring the people, places and things that have left an indelible mark on the region. He can be reached at peisenberg@tribpub.com.

“A fast-growing tree may require more maintenance and may not live as long,” said Sharon Yiesla, plant knowledge specialist in the Plant Clinic at The Morton Arboretum in Lisle. “That makes it especially important to do your research and select just the right species or variety for what you want a tree to do.”

Look at all the characteristics of the tree, not just how fast it grows. Weigh the pros and cons of the tree and see if it is right for your situation.

Some trees that have a reputation for growing up quickly, such as silver maple and cottonwood, have weak wood or poor structure and are susceptible to breaking in storms, she said. Others, such as full-size varieties of arborvitae, may quickly outgrow the space or require frequent trimming.

“There are cultivated varieties of arborvitae that will stay smaller, but you need to choose carefully and not just buy what’s readily available,” she said.

Some trees with a relatively fast growth rate, such as tulip tree and disease-resistant hybrid varieties of elms, can live for decades without causing problems. Other good choices include the native sycamore, with its interesting bark and form; the native hackberry, a sturdy species that resists most diseases and pests; and the native hybrid Freeman’s maple, with its stirring fall color.

“Investigate all aspects of the tree, not just the growth rate,” she said. “Balance the pros and cons as you make a decision.” In some cases, such as a small tree that will only reach 20 feet, a tree that grows slowly may be preferable.

Growth rates are relative. Even slow-growing trees are likely to add 8 to 12 inches a year, Yiesla said. A moderate growth rate usually means 12 to 18 inches a year, while fast-growing trees may add more than 2 feet annually.

Before you choose a tree, take a step back and consider carefully what you want it to do. “If it’s for privacy, there may be a better way to make a screen, such as shrubs or even ornamental grasses,” she said.

Taking the time to select the right kind of tree can save homeowners substantial expense and trouble in the long term. You can use the Arboretum’s Search Trees and Plants tool to look for appropriate trees. It allows you to filter by many criteria, including growth rate. Or consult the Plant Clinic at mortonarb.org/plant-clinic by email, phone or in person.

Pay careful attention to the mature size given for each species or cultivated variety. Remember that trees grow wider as they get taller, and be sure you have enough room. Site any tree well away from paths, driveways and buildings.

Even a tree not known for growing fast will thrive better and grow more if you care for it properly. “Give it plenty of space,” Yiesla said. Spread mulch in an even layer 3 inches deep in a wide ring around the tree, and keep that area weeded.

Most importantly, water the tree well. When a tree is young, it doesn’t have much of a root system to collect and store moisture, so it needs extra help to get enough water to fuel the growth of roots, branches and leaves.

“Check the soil around the tree often to see if it’s moist,” she said. “Water it deeply whenever the top inch or so of the soil feels dry.” It will be at least two or three years before a new tree can be expected to survive on rainfall.

A well-chosen tree, well cared for, can add beauty, shade, privacy and many other amenities to a home landscape. “Just take the time and trouble to choose wisely, to make sure you’re investing in the right kind of tree,” Yiesla said.

For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic or plantclinic@mortonarb.org). Beth Botts is a staff writer at the Arboretum.

— Dan Bolton, Arlington Heights

As I travel around our area, I do see lots of pachysandra plantings that have varying shades of yellow in the foliage. In most situations, this is because the plants receive too much sun. Pachysandra needs to be in shade or partial shade to thrive. The more sun exposure, the more the foliage becomes bleached and yellowed. Pachysandra can only tolerate moderate sun. One bed of pachysandra in my neighborhood with full sun exposure from the west is notably more yellow than green. I am surprised that it has not died out yet.

One key component of successful gardening is choosing the right plants for your garden’s growing conditions. Sun exposure is an essential factor. Sun-loving plants in too much shade will have spindly growth and poor flowering, and can eventually die out. Shade-loving plants in too much sun will have reduced growth and discolored foliage, and can also eventually die out. From your description, it sounds like your bed of pachysandra is getting too much sun and should be transplanted to another place in your garden. Note that removing a tree that shades a bed of pachysandra can increase the sun enough to cause an overexposure problem.

Another worrisome pachysandra trend this spring is a disease called Volutella blight. It begins as small, tan to brown circular spots that form on the leaves and enlarge to form blotches. You can see concentric patterns that form within the brown spots on the leaves as they turn yellow and fall off. The stems can also become infected and turn a brown to black color. The disease tends to be worse in wet areas in the garden. If you have this problem, clean up the dead and diseased plants as best you can. If the disease is not severe, the pachysandra will likely recover. Spraying the pachysandra with a fungicide can benefit in some garden situations. In your garden, I suspect you need to choose a different groundcover that will thrive in a sunny site.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.

With grass supplanted by goldenrod, Black-eyed Susan and milkweed, Varmecky said she wishes her community would do more to bolster green, environmentally friendly initiatives.

A founder of the environmental organization South Suburbs for Greenspace, Varmecky said she’s not very happy with Homewood’s decision to not participate this year in No Mow May, something it promoted last year to support pollinator health.

“They did not give people a ton of notice,” Varmecky said Wednesday. “If they had announced this last fall then people would have had time to do alternate methods.”

The No Mow May movement started in England in 2019 and was introduced in the United States in Appleton, Wisconsin.

Communities in the U.S. have adopted or modified similar efforts.

It has gained traction amid growing concern for populations of pollinators — the bees, butterflies and other tiny critters that help gardens and crops grow — with promoters of no mow suggesting turning suburban yards into springtime buffets for bugs.

Chicago-area suburbs including La Grange Park, Riverside and Westmont last year hosted No Mow ‘Til Mother’s Day, allowing lawns and flowering weeds such as dandelions and creeping Charlie to fully flourish, but only until mid-May.

Homewood announced this week that while it supports pollinator health and environmentally friendly practices, research shows that long-term native planting solutions are more effective than simply not mowing for a few weeks.

The village said the lack of mowing can also negatively affect lawn health by encouraging pests, invasive weeds and allergens.

A village ordinance requires that grass and weeds not exceed 6 inches, a rule it relaxed last May after green lighting the no mow effort.

The village can also place liens on property to recover charges for a cutting service as well as the cost of registering the liens with Cook County.

Homewood officials are encouraging residents to plant native flowers and establishing pollinator gardens and creating bee-friendly yards with diverse, sustainable vegetation.

Homewood Mayor Rich Hofeld said he’d love to keep bee hives in his yard, but has four fruit-bearing apple trees.

He said he has to spray the trees to ward off insects and prevent fungal infections, something that would not be conducive to keeping bees.

“I have to spray if I want to get apples,” Hofeld said Wednesday.

The mayor said he just recently learned of the decision, apparently arrived at by village staff, to opt out of no mow this year.

He said that while the village did get complaints last year about yards looking messy due to lack of mowing, he did not know if that was the overriding concern in dropping the program this year.

“I have mixed emotions about it,” Hofeld said.

He said he has put plantings in his yard to help attract polinating insects, such as hummingbird mint that draws bees, butterflies and hummingbirds.

“I put in a lot of plants that assist in that,” Hofeld said.

Varmecky said she would like to see Homewood support more environmentally friendly efforts.

The village has a tree sharing program, with the community helping susidize the planting of trees in residents’ property. Varmecky said something similar for native plants could be adopted, and she’d like to see the village hold workshops for residents who want to incorporate native plantings on their properties.

“There are tons of pollinator friendly native plants available,” she said. “There are so many different options.”

Because they’re native to the area, the plants tend to thrive, and require far less maintenance, such as regular watering, compared with flowers that are annuals, Varmecky said.

She said she’d started with planting beds along the edge of her front yard containing pollinator plants, and bit by bit got rid of the grass, finishing the undertaking in 2023.

According to Wendy Franzen, president of the Infant Welfare Society of Chicago, Lake Forest Chapter, this 20th anniversary Showhouse represents a massive collaboration of generosity and talent by designers, volunteers, and community partners.

“The draw of the Lake Forest Showhouse and Gardens is an invitation to walk through a fantasy world, to experience the colors, the textures and the creativity of interior designers and landscape architects, unencumbered by a client,” Franzen said.

The 2025 Showhouse, Pembroke Lodge, is a limestone Georgian-style Lake Forest home, designed in 1895 by Henry Ives Cobb, historically significant as one of the earliest estates developed along Lake Forest’s Green Bay Road.  Originally built on nearly 40 acres with landscape architecture by Frederick Law Olmsted, the home was designed to take advantage of sunsets over the prairie landscape, according to a press release.

“This year’s Showhouse is grandiose for us in many ways, to bring back this storied country estate to its rightful elegance, after literally taking the 15,000-square-foot house down to the studs, and in spite of a couple of indelicate past renovations,” Franzen said.

Pembroke Lodge was originally built for real estate and zinc mining entrepreneur David Benton Jones and remained in the family for 67 years. After David’s death, his daughter, philanthropist Gwethalyn Jones, sold over 31 acres to School District 67, where the City of Lake Forest’s Deer Path Middle School now resides. In 1935, the 30-room estate saw the addition of a tennis court with a warming hut and a pool house and pool designed by David Adler with interiors revised by both Adler and his sister, famed interior designer Frances Elkins, according to the history of the property provided at the event.

Franzen says they want the visitor to be inspired to think out of the box and then to take a piece of that inspiration home with them.

“Creating the experience of walking through the space, to get a taste of what each designer is trying to say to you, is a magical moment,” Franzen said.

The Showhouse becomes a revelation of the designer’s ability to honor and interpret the history while adding a freshness to the interpretation.

Designers like George Markoutsas, CEO, Ablaze Design Group in Highland Park, and his multisensory and nature-textured kitchen, reimagined with elements of Biophilic design, an air purification system, concealed appliances, and light fixtures that mimic the body’s natural circadian rhythm.

Or Chicago designer, Lauren Collander, and her transformation of the first floor hall and stairwell, provides something akin to a walk through a Parisian garden, with a custom sapphire stair runner, a wallcovering glittering with hand embroidery, and a bourbon bar for entertaining.

Visitors also have direct access to buy beautiful products they find within each room, Franzen says, offering a shopping connection that further elevates the experience of great design.

“This year is proving to be a huge year for us, with our pre-registration numbers at an all-time high, we hope to raise a million dollars this year,” Franzen said.

Franzen says, all proceeds from the home benefit The Infant Welfare Society of Chicago. Founded in 1911, the Infant Welfare Society of Chicago provides community-based health care to underserved Chicago area families through its Logan Square (Chicago) clinic.

Dana Palmer of Glenview attended opening day, Saturday.

“It’s beyond satisfying to experience such a variety of design styles, and to see how they come together to create such an intimate experience, it’s just breathtaking,” Palmer said

Elizabeth Foran of Lake Forest attended with friends.

“Each room has its own character and offers a unique nod to the history of the house, truly a feast for the senses,” Foran said.

Gina Grillo is a freelancer for Pioneer Press.

“We often think about planting trees around Arbor Day at the end of April, because we know more trees make the world better,” said Sharon Yiesla, plant knowledge specialist in the Plant Clinic at The Morton Arboretum in Lisle. “But it’s just as essential to make sure that the trees we’ve already got are in good health.”

Large, mature trees are the ones that do good work for us, providing shade, capturing stormwater, handling air pollution, and making our communities more beautiful, safer and more restful. A tree you plant now will take decades to reach a really powerful size, so the trees that are already big are worth our attention, too.

How can you tell whether a tree is in good health? “Keep an eye on your trees all the time,” Yiesla said. “Get to know what’s normal for them, and watch for things that are different.” Then get expert help to figure out whether the difference is a problem.

“What’s normal for one kind of tree may be abnormal for another kind,” she said. The critical question is whether this particular tree looks different from how it did in other years, when you know it was healthy.

Some tree symptoms may be caused by diseases or pests; others may be caused by stress, such as compacted soil, drought or severe weather. “Sometimes it’s nothing. Sometimes something bad is happening,” Yiesla said. “You won’t know until you check it out.”

Look at the tree’s canopy of leaves and branches. Does it have fewer leaves than last year? Can you see bare branches at the top?

Inspect individual leaves. Are they normal in size or too small? Are they the same color as usual, or are they too pale or yellowish? Do the veins stand out in a different color of green than the rest of the leaf, indicating that the tree is not producing enough chlorophyll? Are leaves eaten away, leaving only a skeleton of veins?

Watch the blooms. If it is an ornamental tree with conspicuous flowers, such as a magnolia, redbud or horse-chestnut, does it flower the way it normally does? Or are there fewer flowers this season?

Be alert for fall color. An early color change is a sign of stress. “If you see fall color in July, there’s a problem,” Yiesla said. Often in summer, the problem is drought stress, and it’s an urgent call to water your trees in hot weather.

Check out the bark. Are there patches of bark falling off? Are there big cracks, bare places or bulges? Are there places where the bark is discolored or feels damp on a dry day? Can you see sap flowing down the bark? Are there fungi growing on the trunk? They can indicate rot inside.

Examine the branches. Look for wounds or places with cracked or peeling bark, especially if these occur in more than one place; they may be a sign of canker diseases. Also, look for swellings and growths around branches. “These may be harmless insect galls, or they may indicate a serious fungus disease such as black knot,” she said.

Hunt for eggs. Many insects lay their eggs in masses on the bark of trees. Fuzzy beige patches are likely to be spongy moth egg masses. Small light bumps may be spotted on lanternfly eggs. Get any suspected egg masses identified by an expert before you spray with pesticides or take any other action.

To figure out what may be ailing your tree, take clear pictures and submit them to the Plant Clinic (mortonarb.org/plant-clinic) or other experts, such as university extension services. Take closeups of the top and bottom of damaged leaves, and also farther-away photos that show the overall shape and condition of the tree.

The Plant Clinic can also help you identify a tree if you don’t know what kind it is. “Many diseases, pests and stresses only affect certain tree species, or they affect some kinds of trees differently,” Yiesla said. “You’ll be able to take better care of your tree if you know its name.”

For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic, or plantclinic@mortonarb.org). Beth Botts is a staff writer at the Arboretum.

— Jason Kim, Park Ridge

Core aeration is an important maintenance task for maintaining a lawn and I prefer it over power raking. A power rake is a machine with rotating tines that mechanically lift and remove thatch, which then needs to be removed from the lawn. You do not need to both core aerate and power rake your lawn. Most lawns in the Chicago area consist of cool-season grasses like bluegrass cultivars and different fescues. These grasses are most vigorous during cool and moist seasons, making spring and fall the best times to aerate lawns. Generally, aerating a lawn once a year is adequate unless the lawn gets a lot of traffic. In that case, twice a year might work better.

Core aeration is done with a machine that puts holes in the lawn, brings up plugs of soil, and leaves them on the surface. The lawn should be moist but not wet for best results. You can rent a core aerator or contact a landscaping service to have the work done for you. The machine is heavy, so you must have it delivered or use a ramp to get it into and off the back of a truck if you want to do the work yourself. Mark any sprinkler heads or light fixtures in the lawn to avoid damaging them as you aerate.

Core aeration is best for a lawn maintenance program because when it removes a plug of soil, it creates air pockets to improve aeration. This, in turn, reduces compaction and promotes healthy root growth. Spike aerators can cause more compaction by pressing soil down to make the holes, but walking around your lawn with spiked shoes is not helpful. Holes from core aeration allow water and nutrients to reach the root system more easily, while helping to break down the thatch layer.

Thatch is a layer of dead and decaying organic matter that builds up on the soil surface of the lawn. Grass roots into the thatch layer as it gets deeper, which makes the lawn more susceptible to drought stress. I seldom see lawns with a serious thatch problem, which I define as a depth approaching an inch. The cores should be left on the surface of the lawn and will break down over time. Core aeration also creates an opportunity to overseed your lawn.

You can check for excessive thatch by using a sharp spade to cut and lift a small section of lawn, especially if you’ve noticed the lawn has been slower to green up this spring. I rarely see lawns that look like they need a power rake. Only one lawn I saw over these many years of gardening would benefit from power raking, but that was for an owner who wanted immediate results. Power raking does remove some live grass, but I have used a power rake to loosen up soil in preparation for seeding. To correct a thick layer of thatch, though, it would take more than one gardening season using core aeration alone.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.

— Dan Jefferson, Waukegan

I saw a couple of lawns with a lot of crabgrass last summer. Generally, crabgrass thrives in lawns that are cut short and in drier areas near pavement. Fortunately, crabgrass has not been an issue in my lawn at home. Crabgrass is an annual, weedy, warm-season grass that prefers the hot and dry summer weather over the cool spring and fall temperatures that bluegrass prefers. It can blend into your lawn during the summer if you do not pay close attention. When you look closely, crabgrass can be identified by its wide leaf blade and light green color. It is easy to recognize when it grows in severely stressed areas, like along a driveway where the soil has been compacted from vehicle traffic. Thin areas in the lawn provide an opportunity for crabgrass and other weeds to move in. During the summer, this low-growing weed can also be identified by its seed spike resembling a turkey foot. The seeds turn a maroon color when temperatures begin to cool down in fall. Freezing temperatures kill this weed, resulting in patches of brown throughout your green lawn in fall.

The best way to prevent crabgrass is to maintain a healthy lawn that is thick and outcompetes crabgrass. Mow your lawn at 3 to 3 1/2 inches to promote a deep root system. This enables the lawn to better withstand stress and remain dense to help shade out weeds like crabgrass. I consider my home lawn low maintenance, and mowing high has worked well to exclude crabgrass. Thin areas like those in your lawn allow light to penetrate to the soil, which gives crabgrass seed as well as other weed seeds an opportunity to germinate. Light, frequent watering also favors the development of crabgrass.

If the infestation of crabgrass in your lawn last year was significant, you may need to use a pre-emergent herbicide now. These work to prevent crabgrass seed from germinating. Crabgrass preventer products must be applied before crabgrass begins to germinate after soil temperatures reach 55 degrees Fahrenheit for several days in a row. Germination timing can vary from year to year due to the weather. In a typical spring, apply the herbicide in early to mid-April. You may need to adjust timing if it is an exceptionally warm or cold spring. Most crabgrass preventers last for around 60 days, so you do not want to apply them too early in the season. They work by forming a chemical barrier that prevents seeds from germinating. Crabgrass generally germinates when redbud trees bloom, so apply crabgrass control about two weeks before they flower. It is important to read the instructions on any chemical products you choose to use.

There is no need to use a crabgrass preventer if you did not have more significant problems with crabgrass. The herbicide will also prevent some other annual weed species from germinating as well as grass seed, so don’t seed your lawn for at least two months after applying it. You should not do any raking, power raking or core aerating after you have applied crabgrass preventer to avoid breaking the chemical barrier formed by the crabgrass preventer.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.