Fruit Trees for Decorah and the Iowa Driftless

On January 30, 1951, NOAA's Decorah station, down in the Upper Iowa valley at 860 feet, read −43°F. In the same cold snap the Waukon station, out on the upland about 400 feet higher, bottomed at −31°F, and Cresco's at −30°F. That 12°F to 13°F gap between the valley and the high ground is what growing fruit trees for Decorah and the Iowa Driftless comes down to. This map covers Winneshiek County and western Allamakee County in Northeast Iowa, plus a sliver of Howard County: Decorah, Waukon, Calmar, Ossian, Castalia, Spillville, Fort Atkinson, Ridgeway, Burr Oak, Dorchester and the crossroads hamlets in between.

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 uses. The spring layer shows how much warmer or colder a spot runs than Decorah on a still, clear night at bloom.

Decorah plans for −38°F, MFTC zone 3a, with a typical winter of −23°F. It's the reference town, and an odd yardstick, because it sits at the bottom of the map. The middle of the growing ground plans for −33°F, and half of it falls between −35°F and −32°F. The cold end, −37°F to −38°F, is the Upper Iowa floor at Decorah, Freeport and Kendallville. The warm end, −29°F to −30°F, is the ridge ground east of Decorah toward and around Waukon (Thoten, Hanover, Elon, Church) and Castalia on the southern upland. Elon and Castalia are the only named spots in MFTC zone 4a.

Why the map looks the way it does

This is the Driftless Area, the corner of the Upper Midwest the glaciers went around, also called Bluff Country or the Paleozoic Plateau: a limestone and dolomite plateau capped with loess, about 1,150 to 1,345 feet up, with rivers cut deep into it. The Upper Iowa comes in from Minnesota past Kendallville and Bluffton and runs through Decorah between steep bluffs. The Turkey starts near Cresco and runs through Spillville and Fort Atkinson, and the Yellow River heads east through Allamakee County to the Mississippi near Marquette. Decorah sits in the Upper Iowa valley at 880 feet, 350 to 460 feet below the upland villages around it: Calmar, Ossian, Burr Oak, Waukon and Hesper.

On a clear, calm night the ground radiates its heat to the sky and the air touching it turns cold and heavy. Off the upland it slides into the draws and creek valleys, and on the valley floors most of the pool is made right in place, with warmer air sitting on top. In the 12 biggest cold outbreaks in NOAA's records here, Decorah was the coldest station, or tied for it, 11 times, and every time but one that Waukon also reported, Decorah ran 5°F to 13°F colder: −33°F to −20°F in the February 1971 outbreak, −41°F to −34°F in February 1996. In the 1995-96 winter the automated station at the Decorah airport, at 1,157 feet, bottomed out at −31°F while the valley station, nearly 300 feet lower, hit −41°F.

The catch is that in an ordinary winter the long-record stations sit close together. Decorah's average yearly low is −24°F and Waukon's −22°F, and no long-record pair here differs by 3°F or more in a typical year. The valley pulls away on the worst nights, the clear, still mornings after an arctic front over fresh snow, and those are the nights that kill trees. It doesn't always go that way. In the February 1899 cold wave Cresco's lows averaged about −31°F to Decorah's −29°F, and in the January 1972 outbreak Cresco read −31°F to Decorah's −28°F. Flips like that usually come when arctic air arrives on a wind: the air stays stirred, so there's no inversion and higher ground gets no edge.

The map also warms toward the east. Cresco, just off the west edge at 1,255 feet, and Waukon, at 1,271 feet, sit at nearly the same height, but Cresco usually ran a few degrees colder on the big outbreak mornings (−31°F to −24°F in January 2009), and its 30-year number is −37°F to Waukon's −31°F. The west edge sits on or near the gentler, glaciated Iowan Erosion Surface, broad open ground where the cold made on a clear night has nowhere much to go. Waukon sits at the edge of the deeply cut country with creeks heading off it in several directions, and east of it the land drops more than 660 feet to the Mississippi in the 17 miles of Iowa Highway 9 to Lansing.

Aspect shows plainly here. North-facing cliffs along the Upper Iowa hold balsam fir, Canada yew and algific talus slopes, where winter air sinks into cracks in the rock and freezes the water there, and the ice breathes cool air out the bottom of the slope all summer. There's one on Dug Road below Phelps Park in Decorah. At Bluffton Fir Stand the firs grow on a bluff up to 140 feet high, with a goat prairie on the south-facing slope right across from them. Those shaded cliffs and talus slopes are no place for fruit. South faces are hot and dry, good for grapes, but they wake trees up first in spring.

A few things matter less than you'd think. There's no lake to moderate anything (Winneshiek County has about 0.3 square miles of water), and the trout creeks are too small to warm a valley. Downtown Decorah sits on the floor, and the town's heat doesn't beat the pool. South of Waukon the limestone has many sinkholes, and a sinkhole is a closed basin: cold air runs in and can't run out.

The spring layer follows the same drainage, only sharper, since spring frost pools usually top out 30 to 200 feet above the ground. Ridge ground 240 to 350 feet above its floor reads 9°F to 11°F warmer than Decorah on a still bloom night, while creek bottoms like Highlandville read 5°F colder. On a windy or cloudy night the pattern flattens out.

Decorah, Luther College and the Upper Iowa floor

Decorah grew up where the Upper Iowa runs between steep bluffs, with its springs (Dunning's Spring, Siewers Spring, Twin Springs Park). Downtown along Water Street is on the floor, and so is the lower part of Luther College's campus, where the river runs right through it. The town point sits at 880 feet, 20 feet above the floor: −38°F, MFTC zone 3a, typical winter −23°F. Within 3 miles the floor runs −38°F, the bottom of the map. Freeport, on the river bottom 2 miles east, plans for −37°F and reads 3°F colder than Decorah at bloom.

Climb out, toward the bluffs where Phelps Park and Palisades Park sit or onto the upland beyond, and it changes fast. Within 3 miles of town the benches and slopes 100 to 700 feet above the floor run a median −34°F, and the warmest tenth −33°F. A Hungarian study of 69 clear, calm nights found a valley floor averaging 6.7°F colder than a slope 230 feet higher. Springwater, on a hillside 170 feet up and 6 miles north-northeast of town, plans for −34°F but reads 10°F warmer than Decorah at bloom, because the cold drains past it.

On a lot down by the river, plant what has come through −40°F or colder, and lean on the −45°F kinds: Haralson and Honeycrisp apples, Toka plum and Evan's Bali tart cherry. Westcot apricot (−45°F) will take the winter, but it blooms first, so give it the highest spot you have.

Kendallville, Bluffton and Burr Oak, up the Upper Iowa

Above Decorah the Upper Iowa winds between limestone bluffs, past the canoe put-in at Kendallville. Kendallville, at 1,069 feet, plans for −38°F (3a) with a typical winter of −23°F and reads 2°F colder than Decorah at bloom. Bluffton, 9 miles northwest of Decorah, plans for −35°F (3a) and reads 3°F colder. A 1938 survey found balsam fir most abundant near Kendallville and Bluffton. Burr Oak, up near the Minnesota line (the Laura Ingalls Wilder Museum is in its old Masters Hotel), sits at 1,233 feet but only 40 feet above its local floor: −35°F, MFTC zone 3b, typical winter −20°F, 2°F colder than Decorah at bloom, with the floor nearby at −37°F and the benches at −35°F. Up here the −40°F list is the safe one, and the fruit ground is the shoulders above the river with a clear run downhill.

Hesper, Highlandville and the creeks north of Decorah

Hesper, 5 miles east-northeast of Burr Oak, is the highest named spot on the map at 1,343 feet, 180 feet above its floor: −33°F (3b), 7°F warmer than Decorah at bloom. Locust, also 180 feet up, plans for −32°F and reads 6°F warmer. Drop into the creek country east of there and it flips. Highlandville, in a creek bottom at 951 feet, plans for −36°F and is the coldest named spot on the spring layer, 5°F colder than Decorah. Quandahl, 3 miles east at 822 feet, plans for −36°F and reads 4°F colder. Sattre, on a hillside 210 feet above its floor, plans for −32°F and reads about 10°F warmer than Decorah. Same few miles, a 15°F spread at bloom.

Waukon and the Allamakee ridges

Waukon sits on its limestone plain at 1,245 feet, 100 feet above its floor, with Paint Creek running out the south side of town, Village and French creeks to the north and Norfolk Creek starting on the west edge. Iron Mine Hill, about 3 miles northeast, is called the highest point in northeastern Iowa. The town plans for −32°F, MFTC zone 3b, with a typical winter of −19°F, and reads 3°F warmer than Decorah at bloom. Within 3 miles the creek floors run −35°F and the benches −31°F. Plant on the plain or a slope, never in the bottom of a sinkhole.

East and north of Waukon is the warmest ground on the map. Elon, 8 miles east and 290 feet above its floor, plans for −29°F, MFTC zone 4a, with a typical winter of −16°F, and reads 10°F warmer than Decorah at bloom. Church (−30°F), Hanover (−30°F) and Lycurgus (−31°F) sit 240 to 300 feet up and read 9°F to 11°F warmer. This is where Siberian C peach, Lapins and Gold sweet cherries and Hardy Iowa apricot (all −35°F) belong, and on the warmest of it, Contender peach (−30°F). The valleys run colder. Dorchester, on the Upper Iowa floodplain at 755 feet, plans for −36°F, and Maud (−34°F) and Sixteen (−33°F) read 4°F colder than Decorah at bloom even with milder winter numbers. A valley bottom is a frost pocket in May wherever it sits.

Thoten, Frankville and the ridges between Decorah and Waukon

Thoten, 7 miles east of Decorah toward Waukon, sits 350 feet above its floor, the most of any named spot: −30°F, typical winter −17°F, 10°F warmer than Decorah at bloom. Frankville plans for −31°F and reads 6°F warmer. Nasset, on a 30 percent hillside, and Canoe, on an 11 percent one, both plan for −33°F and read 8°F and 6°F warmer at bloom, since the cold runs right past them. The low spots are the trap: Moneek, at the foot of a slope 2 miles south of Frankville, plans for −34°F and reads about 1°F colder than Decorah in spring.

Calmar, Ossian and Castalia on the southern upland

South of Decorah the land rises to a broad upland. Calmar, 9 miles south-southwest at 1,257 feet, is flat ground 100 feet above the nearest floor: −33°F, MFTC zone 3b, typical winter −19°F, 2°F warmer than Decorah at bloom, with benches nearby at −33°F and floors at −35°F. PIVO Brewery on Calmar's north edge pours cider. Ossian, 11 miles south of Decorah at 1,265 feet, plans for −32°F (3b) and reads 5°F warmer at bloom. Castalia, 5 miles east-southeast of Ossian, does better still: −30°F, MFTC zone 4a, typical winter −18°F, 4°F warmer at bloom. On this upland Superior and Italian plums and Bartlett pear (−35°F) fit, and around Castalia, Liberty apple and Contender peach (−30°F) sit right at the line.

Spillville, Fort Atkinson and the western edge

The Turkey's valley is shallower than the Upper Iowa's: Spillville sits about 190 feet below Calmar, where Decorah sits 380 feet below it. It still pools. Spillville, where Dvořák spent most of 1893, sits right on the river at 1,065 feet: −36°F, MFTC zone 3a, typical winter −22°F, 2°F colder than Decorah at bloom, with benches within 3 miles at −34°F. Fort Atkinson, 4 miles down the valley, plans for −35°F (3a), with benches near it at −33°F. Downstream at Elkader, just south of the map, the Turkey valley read −30°F on February 28, 2015, the lowest in the lower 48 that morning.

West of there the hills flatten toward the Iowan Erosion Surface. Ridgeway, 10 miles west of Decorah and 90 feet above its floor, plans for −35°F (3b) and reads 4°F warmer than Decorah at bloom. Protivin, in the sliver of Howard County on the west edge, is flat ground at 1,151 feet that the map counts as floor: −36°F (3a), 3°F colder than Decorah at bloom, with no bench ground within 3 miles. On a flat upland the whole plain is the pool, and there's no thermal belt to climb into.

Spring frost and bloom in the Upper Iowa country

NOAA's frost dates for 1991 to 2020 show what the valley costs. Decorah's median last 32°F comes May 10 and its last 28°F April 28, and one spring in 10 the last 32°F comes May 21 or later. The first fall 32°F lands around October 3, for 146 frost-free days. Cresco, nearly 400 feet higher, runs May 12 to September 30, 142 days. Genoa Dam 8, at 639 feet on the Mississippi just outside the map, gets 172 frost-free days, with its last 32°F around April 20. You'd expect 400 feet less elevation to buy Decorah a longer season than Cresco; the cold that drains into the valley takes nearly all of it back.

Open blossoms of apple, pear, cherry, peach, apricot and plum all start dying at about 28°F, and NC State's orchard guide figures 3°F to 4°F can separate no crop from a full one, so the 16°F spread on the spring layer, from Hanover to Highlandville, is a big deal. Apples forgive a lot (only about 15 percent of the blossoms need to set), and open haskap (honeyberry) flowers take 19°F.

The April 2012 freeze showed what's at stake. A very early warm spell pushed trees along, then lows in the mid to upper 20s°F hit Winneshiek, Allamakee, Mitchell and Clayton counties from April 10 to 12, and the National Weather Service's storm report says apple orchards lost 50 to 80 percent of the crop. An early spring isn't a safe spring; it pulls bloom into weeks that still freeze.

So site comes first; the FAO's frost protection manual calls it "the single most important method of frost protection." Give apricots, peaches and sweet cherries your highest ground with a good spring reading, apples and pears the middle, and haskap and the bush fruit whatever's left. An east-facing slope is ideal, since it warms quickly on a frosty morning, and a north slope holds early bloomers back. Clear brush and fencerows across the bottom of a slope so the cold can run out. Through bloom, mow under 2 inches, don't till, and water a day or two before a frost. Frost cloth of 0.5, 0.9 and 1.5 ounces per square yard gains about 4°F, 6°F and 8°F.

What the weather records say

Decorah's station has 118 years on file and holds the area's record, −43°F on January 30, 1951, the same morning Genoa Dam 8 on the Mississippi read −43°F. Other big outbreaks took it to −41°F in early February 1996, −33°F around March 1, 1962 and −36°F in late December 1950. On the upland, Cresco's station holds −36°F (February 2 and 3, 1996), Waukon's −34°F (February 2, 1996) and Postville's, just southeast of the map, −31°F (January 5, 1924). In the cold wave at the turn of February 2019, Decorah and Mabel, just over the Minnesota line, both hit −37°F while Postville bottomed at −28°F. Our planning low is built on records since the 1995-96 winter, so 1996 and 2019 are both in it.

Iowa State lists Decorah as USDA zone 4b/5a on the 2023 map, with only small parts of Northeast Iowa left in 4b. Ours reads more than a full zone colder: 3a on the Decorah floor, 3b over most of the upland, 4a at the warmest spots. That's not a fight about the weather. USDA's zones are built on the average of each winter's coldest night, and Decorah's typical winter on our map, −23°F, is a 4b number right in line with theirs. Ours is built on the bad night, and NOAA station records show the worst night in about 30 winters runs a median 13°F below a station's average winter low. Iowa State's Aaron Steil makes the same point: a −25°F to −30°F winter can still kill plants rated for 5a.

What you can grow here

Every plant we sell is zoned to the coldest temperature it has actually come through. At or below your planning low is a good pick, up to 5°F warmer is worth a try in a good spot, and well below gives you room for what a winter number misses.

Ridges and upland that plan for −32°F or warmer

Waukon, Ossian, Castalia, Locust, Frankville, Thoten, Elon, Church, Hanover and Lycurgus. This is the ground for early bloomers: Lapins, Gold and Black Gold sweet cherries, Siberian C peach, Hardy Iowa apricot, Superior and Italian plums, Bartlett and Seckel pears, and Macoun and Ashmead's Kernel apples, all −35°F. Lapins and Gold are the hardiest sweet cherries we've found, but they bloom early, so give them your highest ground, just off the windswept crest. Siberian C ripens very late; give it your warmest spot. Marquette and Frontenac grapes (−35°F) want a south face. On the −29°F to −30°F ground around Elon, Castalia, Church, Hanover and Thoten, Contender peach and Liberty and Northern Spy apples (−30°F) clear the number right at the line.

The middle ground, −33°F to −36°F

Calmar, Hesper, Burr Oak, Ridgeway, Spillville, Fort Atkinson, Protivin, Bluffton, Dorchester and most of the creek country. The −40°F list is the core: Zestar!®, Cortland and Prairie Spy apples, Ure and Summercrisp pears, Alderman and Pipestone plums, Meteor tart cherry and Sungold apricot, with Haralson, Honeycrisp and Toka (−45°F) for extra margin. The −35°F kinds clear the warmer half of this band and are worth a try at −36°F only on your highest, best-drained spot. Many fruit trees need a pollenizer, a second variety blooming at the same time; our pollination maps show which ones pair up.

The Upper Iowa floor, −37°F to −38°F

Decorah, Freeport, Kendallville and the low spots on the creeks. The station in town has seen −41°F and −43°F, so give yourself room: Haralson, Honeycrisp, Frostbite and Wolf River apples (−45°F), Kerr and Centennial applecrabs (−50°F), Trailman (−60°F), Bolshaya pear (−50°F), Brookgold plum (−50°F) and Evan's Bali tart cherry (−45°F). If you only plant one tree down here, make it Kerr or Trailman. Centennial, a Wealthy and Dolgo cross from the University of Minnesota, came through a −47°F winter at Ed Schultz's farm in Gallatin Gateway, Montana with zero winter injury. Bush fruit is the safe bet: Honeyberry, Montana Black Currant, Nanking Cherry and Valiant grape, all −50°F.

Roots, snow and site

Roots are the weak link: dormant apple wood can take about −40°F, but the roots are seriously hurt near 10°F and get through winter because soil and snow keep them warmer than the air. At Ed Schultz's, Bud 118 apple rootstock has seen near −50°F under snow with no damage. The floors hold snow while wind can scour a ridgetop bare, so on an exposed ridge use the hardiest rootstock and mulch. Test drainage first (dig 2 feet down, fill the hole, let it drain, refill: under 10 hours is well drained), since ridgetops and steep slopes here often have bedrock close under thin soil. Taper water from mid-August so trees harden off before an early freeze; after the Armistice Day freeze of November 11, 1940, Iowa's 1941 apple crop was about 15 percent of normal.

Local problems

Deer, voles, mice and rabbits. Seed Savers has had deer jump the 8-foot fence at Heritage Farm, finds voles and mice can hurt more young trees than deer, and sets trunk guards about 20 inches above the expected snow depth. Paint young trunks white against sunscald (white interior latex cut 50 percent with water, put on in late fall on a day above 50°F). Keep trees off the floodplain; the Upper Iowa crested at a record 22.5 feet at Dorchester in June 2008.

Fruit history here

The big story is Seed Savers Exchange, founded in 1975 by Kent Whealy and Diane Ott Whealy, which bought its Heritage Farm in 1986: 890 acres about six miles north of Decorah. Its Historic Orchard was grafted from 277 old apple varieties in February 1989. In 2013 orchard manager Dan Bussey brought in 180 historic Upper Midwest varieties from Nick Botner, and the first trees went into the Amy P. Goldman Heritage Orchard. The two orchards now cover about 10 acres with about 1,200 apple varieties, open for walking, tasting and picking. Two of their old varieties are ones we sell: Golden Russet (−40°F), which fits anywhere on this map, and Roxbury Russett (−30°F), which belongs on the warmest ridges. The Upper Mississippi River Valley AVA covers this corner of Iowa and favors south-facing slopes for grapes like Marquette and Frontenac; for a white, our La Crescent has come through −40°F. Down on the Mississippi at Marquette, where the Yellow River comes out, see our Prairie du Chien, Richland Center and the Kickapoo map; up the Mississippi, our La Crosse and the Driftless map.

Questions people ask

What growing zone is Decorah, Iowa?

Decorah plans for −38°F, MFTC zone 3a, with a typical winter of −23°F. Iowa State lists Decorah as USDA zone 4b/5a on the 2023 map; USDA's zone is based on an average winter, ours on the bad night we plan for. Up on the ridges toward Waukon and Castalia the number runs −29°F to −32°F (zones 3b and 4a).

When is the last frost in Decorah?

NOAA station records for 1991 to 2020 put Decorah's median last 32°F on May 10 and its last 28°F on April 28; one spring in 10, the last 32°F comes May 21 or later. The first fall 32°F comes around October 3, for about 146 frost-free days. Ridge ground reads up to 11°F warmer than town on a still bloom night.

Why is Decorah colder than Waukon and Cresco?

Decorah sits in the Upper Iowa valley, 350 to 460 feet below the upland towns, and on clear, calm nights cold air drains off the upland and pools on the valley floor. Its station holds a −43°F record against Waukon's −34°F and Cresco's −36°F.

Can you grow peaches in northeast Iowa?

On the ridges, with care. Iowa State calls zones 4b and 5a risky for reliable peach crops, with fruit buds starting to suffer around −13°F to −18°F. Siberian C (−35°F) fits upland that plans for −35°F or warmer, like Waukon, Ossian and Castalia, and Contender (−30°F) only the warmest ground, like Elon and Castalia. Count on the tree before you count on a crop.

Can sweet cherries grow around Decorah?

Iowa State recommends sweet cherries only for the southern two-thirds of Iowa, and they bloom early enough to lose crops to late frost. Lapins, Gold and Black Gold (−35°F) clear ridge ground that plans for −35°F or warmer but not the −38°F valley floor, so put them high, like Thoten, Hanover or Elon. Evan's Bali tart cherry (−45°F) fits anywhere on the map.

Where are the frost pockets around Decorah?

The Upper Iowa valley floor at Decorah, Freeport and Kendallville plans for −37°F to −38°F, the coldest on the map. In spring the creek bottoms are worst: Highlandville reads 5°F colder than Decorah on a still bloom night, and Quandahl, Maud and Sixteen about 4°F colder. The sinkholes south of Waukon are closed basins that trap cold air too.

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.