Fruit Trees for Fond du Lac, West Bend and the Kettle Moraine, Wisconsin

On January 16, 2009, NOAA's station at the Hustisford wastewater plant, on the Rock River below Horicon Marsh, read −32°F. Jackson, 22 miles east on the far side of the Kettle Moraine, read −15°F. That 17°F split is what growing fruit trees for Fond du Lac, West Bend and the Kettle Moraine comes down to. The map covers Fond du Lac and Lake Winnebago's south shore, the Ledge from Lomira to Mayville, Horicon Marsh and the upper Rock River, the Northern Kettle Moraine around Campbellsport and Kewaskum, and West Bend, Slinger, Hartford and Jackson, in Fond du Lac, Dodge and Washington counties of southeast Wisconsin.

Type your address in the box on the map to get the number for your own place, and the list of what we sell that has come through it.

How to read this map

The big number is the 30-year planning low, the number our cold hardiness calculator uses (built from NOAA station records since the 1995-96 winter), with a small nudge for the ground around you. It's a safe number to plan around, not the record and not a promise of how often it comes. The MFTC zone is that number in half zones. The typical winter is an average year's coldest night, the kind of average USDA's map uses. The spring layer shows how much warmer or colder a spot runs than Fond du Lac on a still, clear night at bloom.

Fond du Lac plans for −26°F, MFTC zone 4a, typical winter −14°F, and that's the middle of the map: nine tenths of the growing ground falls between −31°F and −22°F. The warm end is the east side: Saint Michaels and Beechwood near Kewaskum (−21°F), the knobs around Dundee (−21°F to −23°F), Saint Peter and Jackson (−22°F), all MFTC 4b. The cold end is the Rock River country: Neosho, Saylesville, Hustisford and Mayville (−31°F), all MFTC 3b, with Rubicon and Hartford right behind at −30°F. The spring layer runs from 6°F colder than Fond du Lac in the worst hollows to 11°F warmer on McMullen Hill near Dundee.

Why the map looks the way it does

This is two drainages and a lake. West of the Ledge, everything runs to Horicon Marsh: the Rock River's West Branch from Brandon, its South Branch through Waupun, and its East Branch, which rises southeast of Allenton and runs north and west through Theresa and Mayville. East of the Ledge, the Milwaukee River runs south through the moraine past Campbellsport, Kewaskum and West Bend. North, the Fond du Lac River empties into Lake Winnebago at 746 feet, the lowest ground here. The land climbs about 480 feet from the lake to the Dundee hills, but on a still night where the cold ends up matters more.

Horicon Marsh is the cold sink: about 32,000 acres of cattail and open water on peat, silt and clay in an old glacial lake bed, and flat. A wide, shallow basin can pool harder than a valley that drains, and peat gives back little heat at night. The Wisconsin Ledge AVA petition says cold air pools on the flat, low ground south and west of the Ledge and can't drain toward Lake Michigan. The Horicon plant runs a median 4°F colder than West Bend Public Works and 5°F colder than Jackson for the year's coldest night, and the old Burnett station by the marsh holds the map's record, −43°F on January 30, 1951.

Hartford and Slinger, in the moraine, run cold too. Hartford's plant runs 5°F colder than Jackson, 12 miles east, and Slinger's 5°F colder than Jackson only 7 miles away. The moraine's kames and ridges rise up to 300 feet above its lakes, and a kettle is a closed basin: cold air fills it to its lowest notch before it spills. Around Slinger the floor within 3 miles plans for −28°F and the benches −23°F, and the plant's own 30-year number, −28°F, is the floor's. On a clear, light-wind morning in early autumn 2015, NWS Milwaukee named Slinger and Holy Hill the coldest cooperative stations in southeast Wisconsin, at 38°F.

East of the moraine it softens; Jackson is the mildest station here. The map's east edge is within about 10 to 15 miles of Lake Michigan (the AVA petition credits the big lake with moderating winter lows), and on the map the east side plans for −21°F to −25°F while the marsh plans for −28°F to −31°F.

Lake Winnebago is big but shallow, 15.5 feet deep on average, and it freezes hard every winter (ice roads, sturgeon spearing in February). A lake shelters its shore only while it's relatively free of ice, so the Fond du Lac plant by the lake holds a −41°F record from 1951 and averages −18°F for the year's coldest night, no milder than Horicon. Its help comes in spring and fall, when the water's open. The Ledge is the other big player: a cuesta with a short steep face on the west and a long gentle back slope east, walling the marsh basin from Fond du Lac south toward Horicon. Cold pours off its face, so its upper slopes sit above the pool on still spring nights, and the wind farms from Pipe to Brownsville average about 18 mph, wind that stirs out a frost inversion but strips snow off roots. Air over snow runs colder, but 4 to 10 inches of it insulates soil well; after the snowless 2024-25 winter UW-Madison's fruit program found apple damage just below the graft union.

Fond du Lac, Taycheedah and the Lake Winnebago shore

Fond du Lac sits at 761 feet at the south end of the lake, where the East and West branches of the Fond du Lac River meet downtown and reach the lake at Lakeside Park. The city is floor: downtown plans for −26°F, MFTC 4a, typical winter −14°F, with no bench ground within 3 miles; the floor around it runs −25°F to −27°F. The Ledge rises along the east edge (St. Mary's Springs Academy sits on its side), and that's where to look for a better bloom night. North Fond du Lac, northwest of the city despite its name, plans for −26°F. Upstream toward Rosendale (−28°F) and Eldorado (−27°F), the river's flat headwaters run colder; on January 15, 1972 the old Eldorado station read −32°F while the lakeside plant read −26°F.

Taycheedah sits at lake level, 754 feet, with the Ledge behind it: the village plans for −27°F, the benches within 3 miles −24°F. Hunter's Grove, on the flat 3 miles east of downtown, plans for −26°F but reads 3°F colder at bloom. Up on the Ledge, Saint Peter, 6.6 miles northeast and 250 feet above its floor, plans for −22°F (4b) and reads 8°F warmer than Fond du Lac at bloom.

Downtown's −26°F leaves room for Honeycrisp and Wolf River (−45°F), Zestar!® (−40°F), Liberty and Enterprise (−30°F), Luscious pear and Mount Royal plum (−40°F), and Meteor tart cherry (−40°F). Lapins cherry and Siberian C peach (−35°F) clear it too, but they bloom early, so give them the Ledge slopes. Up the lake in Oshkosh or toward Ripon, the Oshkosh and Lake Winnebago map covers you.

Horicon, Mayville, Hustisford and the marsh basin

Horicon sits at 879 feet at the marsh's southern tip and Mayville at 929 feet on the East Branch, with Ledge County Park between them. Horicon plans for −29°F, MFTC 4a, typical winter −15°F; the floor within 3 miles plans for −31°F and the coldest tenth of the ground around it −32°F. The Horicon plant's own number is −31°F, it holds a −36°F record (January 18, 1994), and it read −35°F in the 2019 outbreak. Mayville plans for −31°F with benches at −28°F; Iron Ridge −30°F; Theresa −29°F but 3°F warmer than Fond du Lac at bloom off its 7 percent slope. Hustisford, at 863 feet where the Rock backs up into shallow Lake Sinissippi (frozen enough for ice racing in January), plans for −31°F, MFTC 3b, and Neosho −31°F (3b).

Plant for the record here, with trees that have come through −40°F: Wealthy (−50°F), Haralson and Frostbite (−45°F), Kerr (−50°F) and Trailman (−60°F) applecrabs, Summercrisp pear (−40°F), Toka plum (−45°F) and Evan's Bali tart cherry (−45°F). On peat and clay, test drainage first (dig 2 feet, fill, let it drain, refill; under 10 hours is well drained) and plant the slopes above the flat.

The Ledge: Lomira, Brownsville and the crest

The Ledge is the local name for the Niagara Escarpment. Lomira, at 1,053 feet on I-41, sits on a bench 100 feet above its floor: −27°F, MFTC 4a, typical winter −14°F, and 7°F warmer than Fond du Lac at bloom, with the floor nearby at −29°F and benches at −26°F. Brownsville, where the wind farms end, sits down in the Kummel Creek bottom at −29°F with benches at −26°F. Hamilton and Marblehead, hillsides 70 to 120 feet up between Lomira and Fond du Lac, plan for −24°F and −25°F and read 5°F to 6°F warmer at bloom.

Hochheim, southeast of Mayville and 200 feet above its floor, plans for −28°F but reads 10°F warmer than Fond du Lac at bloom, one of the best spring readings in the west half. Herman Center, near the crest's high point, plans for −28°F and reads 2°F colder at bloom; it's broad and nearly flat, and flat ground radiates with nowhere to send its cold. Huilsburg, on a 9 percent hillside, plans for −30°F but reads 5°F warmer at bloom. Winters stay cold up here because the deepest arctic nights can cover the benches; the slopes pay off in spring.

Most Wisconsin Ledge vineyards face east, and the AVA petition says 50°F groundwater in the dolomite raises spring and fall fogs that help shield vines from frost. Lomira and Hochheim suit Westcot (−45°F) and Sungold (−40°F) apricots, Lapins and Gold cherries (−35°F), and Marquette (−35°F) and Brianna (−40°F) grapes. It's windy, so plant a windbreak at least the height of the trees and 40 to 60 percent dense, never across the slope below them.

Hartford, Slinger and Pike Lake

Hartford, at 981 feet, grew up around an 1844 dam and sawmill on the Rubicon River, with Pike Lake at its edge and the marsh to the northwest. The map plans for −30°F, MFTC 4a, typical winter −16°F, and finds no warm bench: floor and slopes within 3 miles both plan for −29°F. The plant has 72 years on file, a −35°F record (1979 and 1982) and its own 30-year number of −32°F, so that's what I'd plan for in town. USDA puts Hartford in zone 5a on both its 2012 and 2023 maps. West and southwest it gets colder: Rubicon plans for −30°F, and Saylesville, in a draw 3.3 miles southwest, −31°F (3b), below any town or village on the map, and 4°F colder than Fond du Lac at bloom. The Pike Lake hamlet plans for −28°F and reads 3°F colder at bloom.

Slinger, the "Village of Seven Hills," sits at 1,063 feet in the heart of the moraine. The village point, 40 feet above its floor, plans for −26°F, MFTC 4a, typical winter −15°F, and reads 2°F warmer than Fond du Lac at bloom. Its spread within 3 miles, from −28°F on the floor to −23°F on the benches, is the widest of any town on the map. Diefenbach Corners, 1.8 miles northeast on a hillside 110 feet up, plans for −24°F (4b) and reads 6°F warmer at bloom; Ackerville, on the floor, −25°F and 1°F colder. North of Hartford, Allenton sits on the floor at −28°F, while the benches nearby (Saint Anthony, Aurora, Nabob, Saint Lawrence, 100 to 150 feet up) plan for −24°F to −25°F and read 6°F to 7°F warmer at bloom.

Hartford wants the marsh's −40°F list, with Pipestone plum (−40°F) and Centennial applecrab (−50°F). On Slinger's benches and up at Saint Anthony or Nabob, Contender peach and Rainier cherry (−30°F) have room; on Slinger's floor, stick to −35°F trees like Empire apple and Italian plum.

West Bend, Big Cedar Lake and the Milwaukee River

West Bend grew up on a westward bend of the Milwaukee River at 932 feet, partly for the mill power. The map's West Bend point is down by the river at 904 feet: −25°F, MFTC 4a by a hair, typical winter −14°F, even with Fond du Lac at bloom. That's the cold part of town; the floor and benches within 3 miles both plan for −23°F, so the river bottom runs about 2°F colder than the ground around it. The Public Works station, at 980 feet, has a 30-year number of −25°F and read −27°F on January 31, 2019.

Barton, 1.3 miles north, plans for −23°F (4b) and reads 1°F colder at bloom. Villa Park, 2.4 miles west on a hillside 120 feet above its floor, plans for −23°F and reads 9°F warmer than Fond du Lac at bloom, the best of any neighborhood here. Old Hickory, 3.1 miles south on a bench, plans for −23°F and Eagle Ridge Estates, 2.8 miles southwest, −24°F; both read 3°F warmer. Big Cedar Lake, southwest of town, is 932 acres and 105 feet deep; its shore points (Linden Point, Echo Point, Point Lookout) plan for −26°F, and Cedar Lake Hills, on low ground south of them, plans for −26°F and reads 6°F colder at bloom.

Downtown's −25°F suits Honeycrisp, Zestar!® and Cortland apples, Superior plum with Toka, and Lapins cherry. Up in Villa Park, Contender and Blushingstar (−25°F) peaches and Sungold apricot get the bloom nights they need. Down the river toward Germantown, the Milwaukee and Waukesha map takes over.

Jackson, Richfield and the Holy Hill country

Jackson, at 892 feet, plans for −22°F, MFTC 4b, typical winter −11°F, 1°F warmer than Fond du Lac at bloom. Its station's record is only −23°F (February 1, 2019, in 23 years), and its median first fall frost comes October 17, 12 days after Hartford's. Kirchhayn, 3 miles southeast and 80 feet up, plans for −21°F. Richfield plans for −24°F (4b), 2°F warmer at bloom, with the floor nearby at −26°F; Richfield Interchange, on that floor, reads 3°F colder than Fond du Lac at bloom. Dheinsville, Germantown's old crossroads at the south edge, plans for −24°F. Holy Hill sits on a kame near 1,350 feet, but its station, 2 miles east, tied Slinger for coldest on that 2015 frost morning. Here Blushingstar and Redstar (−25°F) peaches clear −22°F, and Harlayne apricot and Stanley plum (−30°F) have room.

Kewaskum, Campbellsport and the Northern Kettle Moraine

Kewaskum, the "Gateway to the Kettle Moraine," grew up on a horseshoe bend of the Milwaukee River at 935 feet and plans for −24°F, MFTC 4b, typical winter −13°F, 1°F colder than Fond du Lac at bloom. Campbellsport, at 1,027 feet, plans for −24°F and reads 2°F warmer; around both, the floor plans for −25°F to −26°F and the benches −23°F.

Around Dundee and Long Lake the moraine stands up in steep knobs. Dundee Mountain, McMullen Hill, Johnson Hill and Conner Hill plan for −21°F to −23°F and read 8°F to 11°F warmer than Fond du Lac at bloom, among the best spring readings on the map, because slopes of 19 to 37 percent shed cold air as fast as it forms. Among them sit kettles (the moraine's run 3 to 200 feet deep), and the Northern Unit has bogs like Spruce Lake Bog, hollows that fill with cold and hold it. Ashford, 4.4 miles west of Campbellsport, reads 6°F colder at bloom. East of Kewaskum, Saint Michaels (a bench 140 feet up) and Beechwood plan for −21°F and read 9°F and 5°F warmer. This is where peaches have the most room: Contender and Veteran (−30°F) and Blushingstar (−25°F) clear −21°F to −24°F, on the knob slopes and benches, never in a kettle. East toward Sheboygan, the Sheboygan and Manitowoc map covers you.

Spring frost and bloom on the Ledge and in the Kettle Moraine

The spring layer follows the same drainage as winter. It reads warmest on steep slopes and high benches: McMullen Hill 11°F warmer than Fond du Lac, Hochheim 10°F, Villa Park and Saint Michaels 9°F, Saint Peter 8°F, Lomira 7°F. It reads coldest in flat bottoms and closed hollows: Ashford and Cedar Lake Hills 6°F colder, Saylesville 4°F, Pike Lake and Hunter's Grove 3°F. Open blossoms of nearly every tree fruit start dying near 28°F, and UW-Madison fruit specialist Amaya Atucha says at full bloom a 1°F difference can decide a crop.

NOAA's 1991 to 2020 records agree. The median last 32°F comes April 28 at the Fond du Lac lakeside plant, April 30 at Jackson, May 2 at the Fond du Lac airport, May 4 at Horicon and May 6 at Hartford; one spring in ten it's as late as May 14 at the lakeside plant and May 27 at Hartford. The last 28°F comes April 13 at Horicon but April 24 at Hartford, so the marsh is the winter cold sink and Hartford the worse spring frost pocket.

On May 14 and 15, 2016 a late frost hit apple blossoms across southern Wisconsin, with losses from none to 95 percent; eastern Wisconsin near Lake Michigan got off lightly because the cold lake holds bloom back. In 2026, when a warm spring pushed bloom into frost, Paul Schwabe of Johnson's Nursery in Menomonee Falls said southeastern Wisconsin was spared more often for the same reason. Lake Winnebago is shallow and freezes over, so don't count on it to hold bloom back that way.

Site is the fix. Put apricots, peaches and sweet cherries on the warmest knobs and benches, and keep apples, honeyberries and bush fruit for flatter ground: only about 15 percent of apple blossoms need to set, and open haskap flowers take 19°F. A hedge or tree line across the bottom of a slope backs cold air up into the trees, so gap it. Through bloom, mow short, don't till, and water a day or two before a frost; frost cloth of 0.5 to 1.5 ounces per square yard gains about 4°F to 8°F.

What the weather records say

The coldest readings in NOAA station records here: −43°F at the old Burnett station and −41°F at the Fond du Lac plant (both January 30, 1951); −40°F at Germantown, just south of the map (January 10, 1982); −36°F at Horicon (1994); −35°F at Hartford (1979 and 1982); −32°F at Hustisford (2009); −31°F at Slinger and −23°F at Jackson (2019). Outbreaks don't hit evenly: on January 11, 1979 Hartford read −35°F and the Fond du Lac plant −19°F. Since 1995, eight of the ten stations reporting here have gone below their own 30-year number at least once, seven of them in the 2019 outbreak, so I like a few degrees of room.

USDA's 2023 map puts Fond du Lac and West Bend in zone 5b (−15°F to −10°F) and Hartford in 5a (−20°F to −15°F). Our MFTC zone for all three is 4a. USDA's map is built on the average winter, and NOAA station records show the worst night in about 30 winters runs a median 13°F below a station's average winter low. Timing matters too: the median first 32°F comes October 5 at Hartford, and a freeze before trees harden off kills at temperatures a January tree shrugs off, so we taper water from mid-August.

What you can grow here

The Kettle Moraine knobs, the east side and the benches: −24°F or warmer

• Apples: Liberty, Enterprise and Northern Spy (−30°F), plus everything below.
• Pears, plums and cherries: Harrow Sweet pear, Stanley plum, Rainier and Montmorency cherries (−30°F).
• Peaches and apricots: Contender and Veteran (−30°F), Blushingstar and Redstar (−25°F), Harlayne apricot (−30°F).

Fond du Lac, West Bend, Slinger and the Ledge: −25°F to −28°F

• Apples: Honeycrisp, Wolf River and Snowsweet® (−45°F), Zestar!® and Cortland (−40°F), Empire (−35°F).
• Pears and plums: Luscious and Ure (−40°F); Superior (−35°F) with Toka (−45°F), a good pollenizer for it (our pollination maps show what else pairs).
• Cherries and peaches: Lapins and Gold (−35°F), Meteor (−40°F), Siberian C (−35°F), Contender (−30°F); Sungold and Westcot apricots on slopes. Worth a try: Blushingstar (−25°F), up to 3°F short, against a south wall in town.
• Grapes and berries: Marquette and Frontenac (−35°F), Brianna and La Crescent (−40°F); honeyberries and Montana Black Currant (−50°F), Consort currant and Hinnomaki Red gooseberry (−40°F).

Horicon Marsh, Hartford and the Rock River country: −29°F to −31°F

With −36°F on record at Horicon, favor −40°F and colder.

• Apples: Wealthy (−50°F), Haralson and Frostbite (−45°F); Centennial (−50°F) applecrab; Kerr (−50°F) and Trailman (−60°F) applecrabs, the ones to plant if you only plant one tree.
• Pears and plums: Summercrisp and Luscious (−40°F), Bolshaya (−50°F); Toka (−45°F), Pipestone and Underwood (−40°F).
• Cherries and apricots: Evan's Bali (−45°F), Meteor (−40°F); Westcot and Morden 604 (−45°F) on the Ledge slopes above the marsh.
• Berries and grapes: honeyberries, Montana Black Currant and Aronia (−50°F), Red Lake currant (−40°F), Valiant grape (−50°F).

Roots are the weak link: dormant apple roots are seriously hurt near 10°F while the wood takes about −40°F, so hold snow over them, mulch on the windy Ledge and scoured hilltops, and don't let the soil go into winter dry. Drip is the only irrigation we advise. UW-Madison sorts its southern Wisconsin list by fire blight and scab: Liberty, Enterprise and Wolf River resist both, Paula Red and Lodi are fire blight susceptible, and it says to skip Bartlett pear.

Fruit and wine here

We found no record of an old orchard district here, and Washington County's visitors guide lists no orchards or u-picks. The Wisconsin Ledge AVA, established in 2012 on a petition by Steven DeBaker of Trout Springs Winery, now counts about 500 acres in 14 vineyards and 24 bonded wineries, growing Brianna, Frontenac, La Crescent and Marquette among others. Apple Works Winery in Germantown sits on a former orchard, and Peck & Bushel in Colgate, just south of the map, bills itself as Wisconsin's largest certified organic apple orchard, with more than 30,000 trees.

Questions people ask

What hardiness zone is Fond du Lac, WI?

Fond du Lac plans for −26°F, MFTC zone 4a, with a typical winter of −14°F. USDA's 2023 map puts it in 5b, up from 5a in 2012. USDA's zone is based on an average winter, ours on the bad night we plan for.

Is Hartford, WI zone 5a or 5b?

USDA says 5a on both its 2012 and 2023 maps. Our map plans for −30°F in Hartford, MFTC 4a, and the wastewater plant's own records give −32°F, with a −35°F record. It has the shortest frost-free season on the map, 150 days.

When is the last frost in West Bend, WI?

The West Bend stations lack a full 1991 to 2020 frost record, but nearby the median last 32°F comes April 29 at Richfield 3 SSW, April 30 at Jackson and May 6 at Hartford. One spring in ten it comes as late as May 15 to 17 at Jackson and Richfield.

Can you grow peaches in Fond du Lac?

Yes, though not a crop every year. UW Extension says fruit buds die below −15°F and calls peaches more feasible near Lake Michigan. The trees are another matter: Siberian C (−35°F) has come through far colder than Fond du Lac's −26°F, and Contender (−30°F) clears it by 4°F. They bloom early, so plant them high on the Ledge, not on the flat.

Why is Horicon so cold?

Horicon sits at the south tip of Horicon Marsh, about 32,000 acres of flat peat, silt and clay. Cold air drains into that basin on still nights and can't get out toward Lake Michigan. The Horicon station runs a median 5°F colder than Jackson and holds a −36°F record; the map plans for −29°F in town.

Does Lake Winnebago protect Fond du Lac from frost?

In spring and fall, a little: the lakeside plant gets 165 frost-free days and a median last frost of April 28, against 150 days and May 6 at Hartford. In deep winter, no. The lake averages 15.5 feet deep and freezes hard, and the lakeside plant holds a −41°F record from 1951.

Warmer spots, colder spots

Here's the number to plan for at named places on the map, warmest first. Each one is the 1-in-30-year low for that spot: the cold hardiness calculator's number from the same weather stations, sharpened by our microclimate model for the ground right there. Zone is our MFTC zone, set by that one bad night, not by an average.

The weather stations behind it

These are the long-record stations in and around this map, with each one's own numbers since the winter of 1995-96. The last column is this map's 30-year number right at the station, which won't match the station exactly: it's a blend of the stations around it, the way the calculator works everywhere.

Source: NOAA records through ACIS, winters 1995-96 through 2025-26. What the "carried forward," "gaps filled" and AWOS rows mean is explained in how our microclimate maps work.