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An illustrated guide to the signs of Minnesota summer

More phenology fun.

This year, Minnesotans suffered more than the usual amount of winter indignities, including, but not limited to, double-digit subzero temperatures and late-season snow.

But summer’s almost here. Want proof? Look to the prairies, gardens and woods to find sure signs in the form of flowers and berries. Here, let us be your guide to the ecological signs of summer in the Twin Cities.

To find the average date of some of summer’s natural occurrences, MinnPost analyzed data from the Minnesota Phenology Network, a group of naturalists who record the timing of seasonal flora and fauna events across the state of Minnesota. The group formed in 2010 and compiles observations from independent phenologists, with some records going back to the 1940s.

Because the date things happen in a given year can vary wildly based on location, we’ve limited our analysis to observations in the seven-county Twin Cities metro area and to phenomena that have three or more recorded observations over time.

All illustrations by Greta Kaul.

Wild prairie rose blooms

Rosa arkansana
June 3

These little pink and yellow beauties are native to much of North America, Minnesota included, and are the state flower of Iowa and North Dakota. They can be found blooming in wild prairies, roadside ditches and in gardens from early June through July.

Earliest observation: May 19 (1998)
Latest observation: June 17 (1997)

Showy lady’s slipper blooms

Cypripedium reginae
June 7

You may recognize the delicate showy lady’s slipper, also known as the pink and white lady’s slipper, as the state flower of Minnesota. The Legislature passed a resolution designating the wild orchid the state’s official flower in 1902, and it was written into law as a symbol of Minnesota in 1967. It’s also a protected plant: it’s illegal to pick the flowers or uproot the plants in Minnesota. The showy lady’s slipper can be found in cool, damp areas, whether bog, wood or prairie, usually starting in June.

Earliest observation: May 24 (1977)
Latest observation: June 18 (1974)

Canadian serviceberry fruit

Amelanchier canadensis
July 16

It’s not particularly well-known that Canadian serviceberries are edible, but some people like to make pies and jams out of them. Their small trees flower out in May and tend to start bearing small, crimson berries, also known as Saskatoons, in June.

Earliest observation: June 2 (2009)
Latest observation: October 17 (2013)

Harebell blooms

Campanula rotundifolia
June 15

These small, nodding, bell-like flowers start popping up around June and continue to bloom all summer. They can be found in lots of spots, from rocky outcrops to prairie.

Earliest observation: June 5 (1977)
Latest observation: July 10 (1961)

Brown-eyed susan blooms

Rudbeckia triloba
June 17

Similar to the black-eyed susan, the brown-eyed susan and its cheery, yellow blooms can be found starting in June in nature and gardens alike. It's considered a species of special concern in the wild because invasive species and agriculture are taking over its turf, according to Minnesota Wildflowers.

Earliest observation: June 2 (1998)
Latest observation: July 2 (2004)

Orange day lily blooms

Hemerocallis fulva
June 26

As invasive as they are ubiquitous, the orange day lily is a sure sign the height of summer's coming. These hearty plants are found just about everywhere, from ditches to gardens.

Earliest observation: June 12 (1976)
Latest observation: July 10 (1960)

Sunflower blooms

Helianthus annuus
June 30

One of summer's most recognizable blooms pops up around late June. It's native to all the lower 48 states, from the Canadian border to Mexico, and favors dry soil.

Earliest observation: June 15 (2006)
Latest observation: July 27 (2001)

Bee balm blooms

Monarda didyma
July 7

A favorite of bees and butterflies, this Minnesota native spouts bright, pointy flowers that bloom from about July through September. It's sometimes used in herbal teas.

Earliest observation: June 25 (1977)
Latest observation: July 20 (1971)

Prairie blazing star blooms

Liatrus pycnostachya
July 17

This fun flower sprouts out of the ground looking like fuchsia-colored rock candy. Found in prairies, fields and gardens, it tends to bloom from July to September. Its spikes bloom from the top down.

Earliest observation: July 7 (1977)
Latest observation: July 25 (1969)

Rattlesnake master blooms

Eryngium yuccifolium
July 19

Among Minnesota wildflowers, the spiky, mace-shaped rattlesnake master has one of the more curious names, which comes from the erroneous belief that it could be used as an antidote to snake venom, according to the University of Wisconsin. Rattlesnake master is listed as a species of special concern because much of the prairie habitat it's typically found in has disappeared, per Minnesota Wildflowers.

Earliest observation: July 14 (1961)
Latest observation: July 28 (1977)

Virginia strawberry fruit

Fragaria virginiana
August 2

These small, sweet wild strawberries blossom around May in Minnesota, and develop ripe fruit around August. This type of strawberry is one of the breeds that went into the hybrid varieties you’ll find in grocery stores. They’re native to all of the continental U.S., according to the USDA.

Earliest observation: June 27 (2011)
Latest observation: September 16 (2009)

New England aster blooms

Symphyotrichum novae-angliae
August 21

These late-season bloomers happily grow most places they're planted. Their flowers are an important source of food for bees into the fall.

Earliest observation: July 20 (1969)
Latest observation: September 5 (1975)

All data supplied by the Minnesota Phenology Network and its volunteers. For more information about the network, visit