April is when Iowa greens up. Woodland wildflowers carpet the timber floor, the first warblers and shorebirds arrive, frogs and toads call from every pond, and the prairie begins to wake. It is one of the most rewarding months to be outdoors in the state, even as cold snaps still interrupt the warmth.
Week by week in April
April 2–8
- The spring ephemeral bloom spreads through the timber — hepatica, rue anemone, trout lily, and the first Virginia bluebells carpet the wooded ravines.
- Migrating shorebirds stage in flooded fields, and at dawn the greater prairie-chickens boom and dance on their leks in the southern grasslands.
- Cabbage whites and the tiny pale-blue spring azure appear along woodland edges as the butterfly season fills out.
April 9–15
- Pasque flower peaks on the Loess Hills, and large-flowered trillium and woodland phlox begin in the rich timber of the river valleys.
- The first yellow-rumped warblers and ruby-crowned kinglets arrive, and brown thrashers sing from the brushy edges.
- Set out cabbage, broccoli, and kale transplants and plant potatoes and onion sets — but hold the frost-tender crops until May.
April 16–22
- The first wave of neotropical migrants arrives — house wrens, barn swallows, and chimney swifts return as the dawn chorus thickens.
- The Lyrid meteor shower peaks around April 22, a modest but reliable shower best seen after midnight from a dark site.
- Redbuds bloom magenta in the southeast and serviceberry whitens the timber edges as leaf-out sweeps north.
April 23–29
- The leading edge of warbler migration reaches the wooded river corridors, the richest morning birding of the Iowa spring beginning.
- Outdoor farmers markets reopen, and the first Iowa-grown asparagus and spring greens appear at the stands.
- The first returning monarchs reach Iowa, worn females from the Gulf states seeking emerging milkweed to lay the first Iowa-born generation.
Birds This Month
April accelerates the spring rush in Iowa. Wetlands still hold migrating waterfowl, and the marshes fill with the courtship displays of returning shorebirds — pectoral and least sandpipers, greater yellowlegs, and American golden-plovers staging in flooded fields. American white pelicans soar over the reservoirs in great wheeling flocks. In the timber, the first yellow-rumped warblers, ruby-crowned and golden-crowned kinglets, and brown thrashers arrive, and eastern phoebes and tree swallows return to nest.
On the prairie and grassland, the male ring-necked pheasants crow and the greater prairie-chickens — at their last Iowa strongholds in the southern grasslands — boom and dance on their leks at dawn. By late month the first chimney swifts, barn swallows, and house wrens are back, and the dawn chorus thickens noticeably.
This month's tip: get to a wooded ravine at dawn late in April — the leading edge of warbler migration, paired with the spring ephemeral bloom underfoot, makes for the richest morning of the Iowa spring.
What's Blooming
April is the great month of Iowa's woodland wildflowers, when the forest floor blooms before the canopy leafs out and shades it. In rich timber along the rivers and ravines, the spring ephemerals carpet the ground: bloodroot, spring beauty, Dutchman's breeches, hepatica, rue anemone, Virginia bluebells, and the nodding yellow trout lily. By late April the white large-flowered trillium and the woodland phlox add to the show, and mayapples unfurl their umbrellas across the slopes.
On the prairie, the pasque flower reaches its peak on the dry hill prairies of the Loess Hills, and prairie violets and golden Alexanders begin. In gardens, daffodils, tulips, and forsythia carry the cultivated bloom, and flowering crabapples and serviceberry start the parade of spring trees.
Garden This Month
April is the busiest stretch of the Iowa cool-season garden. As soon as the soil is workable, direct-sow peas, spinach, lettuce, carrots, beets, radishes, and Swiss chard, and plant potatoes, onion sets, and asparagus crowns. Set out transplants of the brassicas — cabbage, broccoli, cauliflower, and kale — which thrive in the cool, moist weather. This is also the ideal month to plant bare-root and container trees, shrubs, and perennials while the ground is cool and rains are reliable.
Hold off on tomatoes, peppers, beans, squash, and anything frost-tender — Iowa's average last frost runs from late April in the far south to mid-May in the north, and impatient planting is the most common garden setback here. Keep row cover or old sheets within reach for the inevitable late freeze, harden off indoor-started seedlings gradually, and stay off wet soil so you don't compact it.
Zone 4b (far north Iowa): the season opens here now — direct-sow peas, spinach, lettuce, and radishes, plant onion sets and potatoes, and set out cabbage and broccoli transplants. Keep frost cloth ready, as hard freezes are still common through the month.
Zone 5a (central Iowa): a busy month — sow the full range of cool-season crops, plant potatoes and onions, set out brassica transplants, and plant bare-root and balled trees and shrubs while the soil is moist and cool.
Zone 5b (southern Iowa): harvest the first spinach and radishes, succession-sow lettuce and peas, and harden off warm-season seedlings near month's end, though hold tomatoes and peppers until the frost risk passes in May.
What's at the Farmers Market
Outdoor farmers markets reopen across Iowa in late April, and the first truly fresh local produce of the field season arrives. Asparagus is the star — Iowa-grown spears appear at stands and signal that spring has truly turned — alongside the season's first cuttings of spinach, lettuce, arugula, radishes, green onions, and spring greens from field and hoop house. Rhubarb begins coming in, its red stalks a classic Iowa spring crop.
Look also for cold-hardy herbs, bedding plants and vegetable starts from local growers, fresh eggs, and the last of the season's maple syrup and honey. Choose asparagus with firm stalks and tight, dry tips and stand it upright in a little water in the fridge; use tender spring greens within a few days, as they wilt faster than the storage crops of winter.
Night Sky This Month
April's evening sky over Iowa belongs to spring. The brilliant winter constellations sink into the west after sunset, while Leo rides high in the south and the Big Dipper stands directly overhead. Follow the arc of the Dipper's handle to brilliant orange Arcturus rising in the east — 'arc to Arcturus' — and continue the curve to bluish Spica in Virgo, two beacons of the spring sky.
The Lyrid meteor shower peaks around April 22, a modest but reliable shower best seen after midnight from a dark site. This is also a fine season for galaxy-hunting: the realm of galaxies in Virgo and the Leo Triplet ride high, faint targets that reward dark prairie skies and a telescope away from town lights.
Exact planet positions and this year's Lyrid peak timing shift year to year — the printable Iowa night-sky guide gives the current details for your location.
Butterflies & Pollinators
April fills out Iowa's butterfly fauna as the weather warms. The overwintering mourning cloaks, eastern commas, and question marks are joined by freshly emerged spring species. Cabbage whites flutter across gardens and fields, and the tiny spring azure — a flake of pale blue — appears along woodland edges where its host shrubs bloom. The first eastern tiger swallowtails and black swallowtails take wing late in the month, nectaring at early flowers. Red admirals and painted ladies arrive as migrants from the south, sometimes in notable numbers during big flight years. The first returning monarchs reach Iowa toward the end of April or early May — these are worn females that have flown up from the Gulf states, and they immediately seek out emerging milkweed to lay the eggs of the first Iowa-born generation. Watch sunny, sheltered spots, where butterflies concentrate on the warmest afternoons.
Trees This Month
April is leaf-out across Iowa, sweeping from south to north and from the early trees to the late. Silver maples and cottonwoods set their seed and leaf out first, the cottonwoods unfurling sticky, balsam-scented young leaves along the rivers. Serviceberry and wild plum and cherry whiten the timber edges with early blossom, and the redbuds bloom magenta in the southeast.
The oaks and hickories remain cautious, their buds swelling but holding back — the bur oak, black walnut, and shagbark hickory are Iowa's last to leaf out, waiting until the danger of hard frost has nearly passed before risking tender new growth. By the end of April, the river bottoms and lower slopes are in full green while the oak ridgetops still show the gray of bare branches and the soft red of opening buds.
Weather & Daylight
Across Iowa, a typical April day averages a high near 60°F and a low near 37°F, with about 3.7 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
Mild and noticeably wetter, highs in the 60s and lows in the upper 30s, with frequent showers greening everything up.
| Average high | 60°F |
|---|---|
| Average low | 37°F |
| Precipitation | 3.7 in |
| Sunrise (mid-month) | 6:34 CT |
| Sunset (mid-month) | 19:53 CT |
Figures are statewide averages over the 1991–2020 U.S. climate normals; local conditions vary with elevation and distance from the coast. Sunrise and sunset are computed for a midstate point on the 15th (CT).
Next month's version of this page, by email
One short note when Iowa's next month turns — what's arriving, blooming, and worth a night outside.
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The complete Iowa birding, native-plant, and night-sky references — or the whole year, week by week, in one book.
Same month elsewhere: April in Kansas · April in Kentucky · April in Louisiana