Fruit Trees for Spencer, Spirit Lake, Okoboji and the Iowa Great Lakes

On January 2, 2010, NOAA's station at the Spencer airport, about 3 miles northwest of downtown at 1,337 feet, read −37°F, the coldest reading in any station record on this map. In that cold snap the Spirit Lake station bottomed at −29°F and the Lake Park station at −28°F, on ground about 90 to 115 feet higher. A 9°F spread across 17 or 18 miles of gentle prairie is what picking fruit trees for Spencer, Spirit Lake, Okoboji and the Iowa Great Lakes comes down to. This map covers Dickinson County and the north half of Clay County in Northwest Iowa, plus the west edge of Palo Alto County: Spencer, Spirit Lake, Okoboji, Arnolds Park, West Okoboji, Wahpeton, Orleans, Milford, Superior, Terril, Lake Park, Everly, Fostoria, Royal, Dickens and Ruthven.

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 same number our cold hardiness calculator uses (NOAA station records since the 1995-96 winter), plus a small nudge for the ground right 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, and the typical winter is an average year's coldest night, the kind of number USDA's map is built on. The spring layer shows how much warmer or colder a spot runs than Spencer on a still, clear night at bloom.

Spencer is the reference town: −32°F, MFTC zone 3b, typical winter −21°F. The middle of the growing ground plans for −31°F, and half of it falls between −32°F and −30°F. The cold end, −33°F to −34°F, is the lowest ground: the mouth of the Ocheyedan at Spencer and the lake-level shore at Wahpeton and Crescent Beach on West Okoboji. The warm end, −29°F (MFTC zone 4a), is the Spirit Lake town site, Fostoria on its rise between Spencer and Milford, and Birchwood Estates on Spencer's north side. That's only 5°F end to end, but on a bloom night a few degrees can be the whole crop.

Why the map looks the way it does

This is the west edge of the Des Moines Lobe, the glacier ice that sat on this part of Iowa until about 12,000 years ago. Melting back, it left kame-and-kettle country: knobby hills of dropped till, hollows where buried ice blocks melted out, and the deepest hollows full of water. Gull Point on West Okoboji is a textbook patch of kettles, sloughs and knobby hills. The chain of lakes drains out its south end at Milford toward the Little Sioux, which runs southwest past Spencer, where the Ocheyedan comes in from the northwest.

The relief is small. Superior and the town of Spirit Lake sit at about 1,480 to 1,495 feet, the lakes at about 1,398 feet, and Spencer at 1,319 feet where the two rivers meet, the lowest ground on the map. On a clear, calm night the open till plain radiates its heat to the sky, and the chilled air slides into the hollows and river bottoms and pools there under a layer of warmer air. The Spencer airport station has run 3°F colder than both the Spirit Lake and Lake Park stations in a typical year's coldest night (the median over 26 winters). On the bad nights the gap opens: in the late February 1962 outbreak the long-record Spencer 1 N station read −29°F while the Lake Park station, 126 feet higher, read −23°F.

Inside that pattern the map picks out the hollows. A kettle or slough is a closed or nearly closed basin, and a closed basin fills with cold air up to its lowest notch before it spills. The lowest shore ground reads cold too. By midwinter the lakes are frozen, and snow-covered ice is just a big flat floor radiating to a clear sky. As Wisconsin's state climatology office puts it, lakes shelter their shores only when they're relatively free of ice. So Wahpeton and Crescent Beach, near lake level, plan for −34°F, while the knobs 100 feet or more above the floor around them run about −30°F. In the February 2021 outbreak the Spirit Lake station tied the Spencer airport for the coldest reading on the map, −27°F. No station sits on the shore itself, though, so how cold the lake-level ground runs is the map's reading of the terrain, not something a thermometer here has proven.

Wind is the other half. This is open, rolling farm country, and an inversion usually holds only while the wind stays under about 3 to 5 mph (Washington State's orchard numbers). When arctic air comes in on a wind, the bottoms lose their edge or flip. In the February 1933 outbreak the Lake Park station, up at 1,452 feet, was the coldest on the map at −30°F while Spencer 1 N read −26°F, and in the January 2019 outbreak the Spencer airport, at −25°F, was the warmest station. Between the small relief and the wind, the spread here stays far narrower than in hill country.

Towns hold heat on still nights, even small ones, and the map gives built-up ground up to 2.5°F for it. Spirit Lake's town site plans 3°F warmer than the floor around it. In Spencer, the Spencer 1 N station (a mile north of town, by NOAA's naming) has a 30-year number of −30°F to the airport's −32°F and read −30°F to the airport's −37°F in January 2010. Some of that may be town heat and some how the stations sit; the records can't split them.

The lakes do their real work in fall, when open water still holds summer heat. The Spirit Lake station's median first 32°F of fall is October 11, five days after Lake Park's and two weeks after the Spencer airport's. In spring that edge mostly disappears: Spirit Lake's median last 32°F is one day ahead of Lake Park's, and both see their last 28°F on April 14. That's the usual pattern: lakes do less for the last spring freeze than the first fall one. Ground matters too. Wet hay meadows, sloughs and pothole bottoms run cold because they're low, grassy and often organic (the soil in the wettest Des Moines Lobe depressions is even called Okoboji silty clay loam). The gravelly outwash around Milford drains fast, and Iowa State's first rule for a fruit site is good drainage, because fruit trees die within a few years on wet soil.

Spencer, Everly and the river bottoms

Spencer sits at 1,319 feet where the Ocheyedan comes into the Little Sioux. Downtown plans for −32°F (zone 3b), typical winter −21°F. The floor within 3 miles has a median of −32°F and a coldest tenth of −33°F. The river mouth, at 1,307 feet, plans for −33°F with a typical winter of −22°F and reads 2°F colder than downtown on a bloom night. Up out of the bottoms the warmest tenth runs −30°F, and Birchwood Estates, on the north side, plans for −29°F (zone 4a), though at bloom it reads about like downtown. There's no bench ground near Spencer, so you work with small things: a few feet of rise, a south or west wall, staying off the flood ground.

Out on the Clay County farm ground the relief nearly vanishes. Everly, with the Ocheyedan to its south and west, plans for −32°F; Royal, southwest at 1,415 feet, −30°F (right on the line between zones 3b and 4a); and Dickens, on a toe slope east of Spencer, −31°F, running 2°F warmer than Spencer at bloom. The risk out here is a shallow swale with nowhere to drain, and a bare rise where the wind takes the snow off the roots.

On a Spencer lot, anything that has come through −35°F or colder has room: Haralson, Honeycrisp and Freedom apples, Summercrisp and Seckel pears, Pipestone and Underwood plums with Toka to pollenize them (see the pollination maps), and Meteor tart cherry. Liberty (−30°F) is worth a try in a sheltered spot. South of Spencer toward Storm Lake, the Storm Lake, Carroll and Sac City map covers you.

Milford, Fostoria and the south end of the lakes

Milford, the southern gateway to the lakes, sits at about 1,434 feet at the south end of the chain on rich black soil, with gravel pits east, west and south of town. It plans for −31°F (zone 3b), typical winter −19°F, and runs 3°F warmer than Spencer on a bloom night, one of the better spring readings on the map. The floor within 3 miles has a median of −32°F and a coldest tenth of −33°F. The long-record station northwest of town, Milford 4 NW, holds the map's second-coldest reading, −34°F on January 3, 2010, in 81 years on file.

Fostoria, between Spencer and Milford at 1,460 feet and 80 feet above its floor, is the standout: −29°F (zone 4a), typical winter −17°F, 2°F warmer than Spencer at bloom, with knobs at −29°F over a −31°F floor. Gravelly ground on a rise is the best fruit ground at this end of the map. Put apricots like Westcot and Morden 604 there, with Siberian C peach and Black Gold or White Gold sweet cherries, which Iowa State notes are self-fruitful.

Okoboji, Arnolds Park and the east shore

West Okoboji is the odd lake in the chain: 3,847 acres, spring-fed, about 7 miles long and Iowa's deepest natural lake, well over 100 feet deep. Arnolds Park, in the center of the resort district, sits 40 feet above its local floor and plans for −30°F (zone 3b), typical winter −18°F, 3°F warmer than Spencer at bloom; the ground around it runs from −34°F in the coldest tenth to −29°F on the knobs. The city of Okoboji, along the east shore of West Okoboji, sits on an 8 percent toe slope only 10 feet above the floor: −32°F, typical winter −20°F, 1°F colder than Spencer at bloom, with its floor at −33°F and its knobs at −30°F. That 3°F to 4°F between shore and hills is the main thing to know here.

Twin Mounds, a 100-foot hill on East Okoboji's south shore, got seven Lakeside Laboratory stations in 1913 because its timbered north face and bare, wind-exposed south slope ran so different; that study (evaporation, wind and humidity, not temperature) is the only slope-by-slope microclimate work we've found here. For fruit, get up off the shore onto the slope, not the windswept top, and watch the lake roads, hedges and fills that cross a slope, since they back cold air up into the trees just uphill. On knobs at −29°F to −30°F, Rainier and Contender (both −30°F) fit; by the water, stay with fruit that has come through −35°F or colder.

Wahpeton, West Okoboji and the west shore

Wahpeton, "Our Home on Millers Bay," has Gull Point State Park inside the city. The town point sits right at lake level and plans for −34°F, typical winter −22°F, 3°F colder than Spencer on a bloom night. Crescent Beach Resort beside it also plans for −34°F, but on its 7 percent slope it reads about even with Spencer at bloom, because cold drains off a slope even when the bottom below is cold. The village of West Okoboji plans for −32°F, 1°F warmer than Spencer at bloom. Farther north on the west side, Manhattan Beach Resort, Egralharve, Triboji Beach and Beaches Resort plan for −32°F to −33°F. Egralharve sits in a draw and has the coldest bloom-night reading of any named place on the map, 3°F colder than Spencer.

Wahpeton and Crescent Beach run colder than anything on the east shore because they sit lower, 0 to 10 feet above the floor against Arnolds Park's 40, with Gull Point's kettles and sloughs next door. The knobs above still run about −30°F, so the fix is the same as on the east side: climb. At lake level, plant fruit that has come through −40°F or colder, like Wealthy, Haralson, Luscious pear, Evan's Bali tart cherry and Honeyberry, and save the apricots and sweet cherries for the hills.

Spirit Lake, Orleans and Big Spirit

Big Spirit is Iowa's largest natural lake, about 5,684 acres, but it's shallow (24 feet at its deepest), and East Okoboji averages only 10 feet, so both freeze early. The town of Spirit Lake, the Dickinson County seat, sits on the west shore of East Okoboji at about 1,480 feet, 70 feet above its floor, with Big Spirit to the north. It's the warmest town on the map: −29°F (zone 4a), typical winter −17°F, 5°F warmer than Spencer on a bloom night. Height and town heat both help; the lakes help mainly in fall, holding off the first freeze. The floor around town runs −32°F, the knobs −30°F.

Orleans, along Big Spirit near Marble Beach and Mini-Wakan state parks, plans for −31°F, typical winter −19°F, about even with Spencer at bloom. Spirit Lake's town lots are the place for early bloomers: Sungold and Westcot apricots, Gold and Lapins sweet cherries, Siberian C and Contender peaches, and Mount Royal plum.

Lake Park, Superior, Ruthven and the upland edges

Lake Park, at about 1,470 feet with Trappers Bay State Park just west of town, has the warmest floor of any town on the map: a median of −30°F within 3 miles, and only −31°F in the coldest tenth. It sits on high, fairly even ground with no deep pool to fill. The town plans for −30°F (zone 3b by a hair), typical winter −18°F, 2°F warmer than Spencer at bloom. The Lake Park station's 30-year number, −30°F, is 2°F colder than anything it has recorded since 1995 (−28°F). If you're north across the state line toward Worthington, the Worthington, Pipestone and the Buffalo Ridge map covers you.

Superior, at about 1,493 feet, is the highest town on the map, with more bench ground around it than any other: −30°F (zone 4a, on the line), 2°F warmer than Spencer at bloom, knobs at −30°F over a −32°F floor. Terril plans for −31°F. Ruthven, on the Palo Alto County side at 1,437 feet, sits about 90 feet above Lost Island Lake, with Barringer Slough, a restored prairie marsh, on the lake's south side. The lake and slough are where the cold goes. Ruthven plans for −30°F (zone 3b), typical winter −18°F, and reads 5°F warmer than Spencer at bloom, close behind Spirit Lake. That's good ground for apricots like Debbie's Gold, kept away from the slough edge.

Spring frost and bloom around the Iowa Great Lakes

The spring layer follows the same drainage as winter. It reads warmest at Spirit Lake and Ruthven (5°F warmer than Spencer), then Milford and Arnolds Park (3°F), then Lake Park, Fostoria, Superior and Dickens (2°F), and coldest in Egralharve's draw and Wahpeton's lake-level ground (3°F colder than Spencer). NOAA's 1991 to 2020 frost dates show the same split:

• Spencer airport: last 32°F May 8 (one spring in 10, May 19), last 28°F April 23, first fall 32°F September 27, 146 frost-free days.
• Lake Park: last 32°F April 30, last 28°F April 14, 164 days.
• Spirit Lake: last 32°F April 29 (one in 10, May 15), last 28°F April 14, first fall 32°F October 11, 170 days.

Open blossoms of apple, pear, cherry, peach, apricot and plum all start dying at about 28°F (Michigan State's numbers). An apple needs only about 15 percent of its blossoms to set a crop, and fully open haskap flowers take 19°F. Our rule of thumb: unless the fruit is clustered (cherries, grapes), most fruit can lose half its blossoms with little effect. Iowa's statewide freeze of April 10 and 11, 2012 came after a warm spell pushed bloom ahead, and the second night hit 20°F at Iowa State's research station near Gilbert; we couldn't find a report of what it did up here.

Don't count on the lakes to hold bloom back the way Lake Michigan does; we couldn't find a study of it here. Site comes first. Put apricots, peaches and sweet cherries on the best spring ground (Spirit Lake and Ruthven town lots, Milford's gravelly rises, the knobs above the lakes), and apples, haskap and currants lower. Iowa State flags Zestar!®, Wealthy, William's Pride and Liberty as early-blooming apples and Enterprise as a late one. Through bloom, mow under 2 inches, don't till, and water a day or two before a frost. On young trees, bush fruit and strawberries, frost cloth of 0.5, 0.9 and 1.5 ounces per square yard buys about 4°F, 6°F and 8°F (Alabama Extension's numbers).

Little Sioux Orchard near Milford grows Northern Spy only as an experiment, because it ripens so late it's hard to pick before a hard freeze. Taper watering from mid-August so trees harden off. Early cold kills at temperatures a January tree shrugs off.

What the weather records say

NOAA station records here: −37°F at the Spencer airport (January 2, 2010, 29 years on file), −34°F at Milford 4 NW (January 3, 2010, 81 years), −33°F at Lake Park (February 2, 1917, 88 years), −32°F at Spencer 1 N (January 5, 1924 and January 21, 1970, 89 years), and −29°F at Spirit Lake (January 2, 2010, 29 years on file). The January 2010 outbreak set the low at three of those five, including the long-record Milford station, so the worst cold here isn't a thing of the past.

The average yearly low is about −21°F at the long-record Spencer, Milford and Lake Park stations and −19°F at Spirit Lake. NOAA station records show the worst night in about 30 winters runs a median 13°F below a station's average winter low; Spencer's −32°F planning low sits 11°F below its average. Snow averages about 38 to 43 inches a year. Lake ice is shrinking: Spirit Lake's ice season averaged 135 days in 1955 to 1978 and 106 days in 2001 to 2020.

USDA's map is built on the average of each winter's coldest night. One online zone guide puts northwest Iowa at about USDA zone 5a, and the station averages of −21°F and −19°F fall in USDA's 4b and 5a ranges. Our planning lows put this map in MFTC zones 3b and 4a, a full zone or more colder, because we plan for the bad night.

What you can grow here

On a map this tight, the spring layer changes the list more than the winter number does, so let the bloom-night reading decide where the early bloomers go.

Town lots, rises and the upland edge, −29°F to −30°F (Spirit Lake, Fostoria, Birchwood Estates, Superior, Royal, Lake Park, Ruthven, Arnolds Park, the knobs above the lakes): Honeycrisp, Zestar!®, Cortland, Liberty and Enterprise apples; Summercrisp and Seckel pears; Pipestone and Underwood plums with Toka; Lapins and Rainier sweet cherries; Westcot and Sungold apricots; Siberian C and Contender peaches.

The broad middle, −31°F to −32°F (Spencer, Milford, Okoboji, West Okoboji, Orleans, Everly, Dickens, Terril): everything rated −35°F or colder, like Haralson, Spartan, Freedom, Triumph, Summercrisp, Superior plum, Evan's Bali, Lapins and Siberian C. Worth a try in a good spot: Liberty, Contender and Montmorency (all −30°F), on a rise, by a south wall or under good snow.

Lake-level shore, draws and the river bottoms, −33°F to −34°F (Wahpeton, Crescent Beach, Egralharve, Triboji Beach, the Ocheyedan mouth): Wealthy, Kerr and Trailman applecrabs, Luscious pear, Toka and Brookred plums, Evan's Bali and Juliet cherries. Skip apricots, peaches and sweet cherries here.

Berries and vines, anywhere on the map: Honeyberry, Montana Black Currant, Red Lake currant, Pixwell gooseberry and Boyne raspberry. Of the grapes Iowa State calls hardy in northern Iowa, we carry Valiant, Bluebell, Brianna, Frontenac and Marquette, among others.

Roots are the weak link. At Ed Schultz's farm in Gallatin Gateway, Montana, Bud 118 rootstock has seen near −50°F under snow without damage. On open prairie the wind can strip snow off bare rises, the very ground you want for bloom, so hold it with a shelterbelt at least as tall as the fruit trees and 30 to 40 percent dense, gapped at its low end so cold air can drain out. Plant on a gentle slope (Montana State suggests a 4 to 8 percent grade) on well-drained ground with 8 or more hours of sun. Local problems: wet, heavy soils in swales and potholes; wind (Little Sioux Orchard finds Zestar!® drops easily in it); 2,4-D drift onto grapes in corn and soybean country. Iowa State lists Freedom, Liberty, Spartan and William's Pride as resistant to scab, fire blight, cedar-apple rust and powdery mildew, and says Bartlett pears aren't reliably hardy in northern Iowa.

Fruit history around the lakes

Not much is written about old orchards here. Little Sioux Orchard, at 2618 160th Avenue near Milford, is the one u-pick orchard we know of on this map. The family that farms it decided on an orchard in 2011 and planted 1,000 trees on the north side of the farm a couple of years later. They opened to the public in 2017, added 320 trees in 2018, and since 2022 have been readying ground to the west to double the orchard. Their apples run from Redfree in mid August through Zestar!®, Honeycrisp, McIntosh, Cortland, Liberty and Candy Crisp, and Okoboji TWP Ciderworks makes hard cider from them. The orchard is closed for 2026 and reopening in 2027.

Questions people ask

What growing zone is Spencer, Iowa?

Spencer plans for −32°F, MFTC zone 3b, with a typical winter of −21°F. One online zone guide puts northwest Iowa at about USDA zone 5a; USDA's zone is based on an average winter, ours on the bad night we plan for. Across this map the planning low runs from −34°F on the lowest shore ground to −29°F in Spirit Lake and Fostoria (zone 4a).

When is the last frost in Spirit Lake and Spencer?

NOAA station records for 1991 to 2020 put the median last 32°F on April 29 in Spirit Lake and May 8 at the Spencer airport, and the last 28°F on April 14 and April 23. One spring in 10 the last 32°F comes as late as May 15 at Spirit Lake and May 19 at the Spencer airport.

Does Lake Okoboji affect frost?

Mostly in fall. Open water holds off the first freeze: the Spirit Lake station's median first fall 32°F is October 11, two weeks after the Spencer airport's. In midwinter the lakes are frozen and the lowest shore ground plans for −32°F to −34°F, and in spring the last frost at Spirit Lake comes within a day of Lake Park's, so get up on the slopes above the water.

Can you grow peaches in northwest Iowa?

Yes, with the right variety and site. Siberian C (−35°F) clears the planning low even on the −34°F shore ground, and Contender (−30°F) fits the warmest ground, like Spirit Lake, Fostoria and the knobs above the lakes. Peaches bloom early, so put them where the spring layer reads warmest.

What plums grow in northern Iowa?

Iowa State lists the Minnesota hybrids Alderman, Pipestone, Superior and Underwood as hardy statewide, planted with a second hybrid such as Toka as the pollenizer; all of them clear Spencer's −32°F planning low. Mount Royal also grows statewide, while Damson isn't reliably hardy in northern Iowa.

When does the ice go out on the Okobojis?

Anywhere from early March to the end of April. Spirit Lake opened on March 3, 2024, the earliest in DNR records, and West Okoboji held its ice until April 30, 2018, the latest on record.

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.