The Best Summer Alliums to Grow: Plant Trial Results

Attractive, easy to grow, and pollinator friendly, these perennials are worthy of a spot in your garden

Some years ago , during a midsummer trip to Wisconsin , I recover myself impale by a vast planting of ‘ Summer Beauty’alliumdotted throughout with marvellous shiny pink coneflowers ( Echinaceaspp . and cvs . , Zones 3–9 ) . To my eye , this perfect pairing of complementary color but contrast flowered mannikin was just magnificent , and the hum and dance of bee and butterflies brought it all to spirit . I opine this was the minute when I truly came to apprize alliums .

Alliums , or ornamental onions , make up a diverse group of garden industrial plant that includesspring - bloomingbulbs , culinary herbs , and durable perennial with persistent foliage and bountiful summertime prime . bulging Allium — the ones with flowers as big as a Thomas Kyd ’s head , or routinely photograph with one for size comparison — are marvels of the spring garden . Not all are heavy - bloomed or as marvelous as a yearling , but some — like the eye - pop purple balls of towering ‘ Globemaster ’ ( A.‘Globemaster ’ ) or the 12 - in spidery pinkish globes of Schubert ’s allium ( A. schubertii ) place a high bar . While these telling blossom create garden dramatic event , the dormancy that watch over is less thrilling ; the often outsized leaves can take what feels like months to pass by , fall flat over neighboring plants in the meantime and leaving gawp holes behind .

Allium Basics to Know

Alliumspp . and cvs .

Zones:2–11

Conditions : Full sun ; well - enfeeble soil

aboriginal range : Alpine region of the Northern Hemisphere

How to pass around : Simple part in bounce or fall

Pests and disease : episodic folio spot , clay sculpture , onion plant fly front , thrip

On the other bridge player , rhizomatous alliums — still bulbous but modified — pretend more like perennials , producing dense clump of persistent grassy - to - strap - similar leaves that largely remain attractive to the last days of summer . Their individual flower head — technically umbel — may be little but are more bountiful per plant life than fountain fuckup and continue the summer flowered show into fall . And though gardeners love alliums in all their guises , bees and other pollinator are tops fans ! In fact , it is hard for me to intend of alliums without the accompany frenetic soundtrack of buzzing bee .

Our recurrent allium test at the Chicago Botanic Garden germinate organically from a simple comparison of ‘ Summer Beauty ’ to Summer Peek - a - Boo ® , its thick doppelganger . I added ‘ Millenium ’ at the suggestion of a admirer . While we were watching and ranking these initial alliums , others like them crept into the marketand into our trial . I have a notion this is just the commencement , but the followingsummer genus Allium have put on the most impressive show so far .

Trial Parameters

The Chicago Botanic Garden has evaluated 20 blue-ribbon genus Allium since 2010 . Besides mention their ornamental traits , we monitored the industrial plant to see how well they grow and adjust to environmental and dirt conditions , while keep a skinny eye on any disease or pest problems and assessing plant injury or losses over winter .

How long the plants were trialed : Minimum three years

Zone:5b

Conditions : Full Sunday ; well - enfeeble , alkaline , stiff - loam soil

like : We leave minimal care , allowing the plant to thrive or fail under natural conditions .

Top-Rated Alliums

‘Chivette’ Allium (photo above)

My initial reaction to chives in the trial run was “ No fashion , ” but then ‘ Chivette ’ show up and “ Why not ? ” seemed a good response . Chives fit handily into the pop foodscaping movement , and ‘ Chivette ’ is decorative whether you eat it or not . lilac-colored - purple flowers , produced freely for about a month in tardy spring , become ragged look near their death . ‘ Chivette ’ is mostly aseptic , so there is no need to deadhead unless the brown flower chief disturb you . My suggestion is to take a recondite breath , because a blossom of bright green leaves — curly than the early leaves — about two week after flowering does a dependable business of cut across any ugliness . A midseason growth spurt widen ‘ Chivette ’ but does not sum to its height . Yellow leaf tips were common but not bothersome ; the slimy stage after flowering is mercifully brusque .

Summer Peek-a-Boo®

Summer Peek - a - Bronx cheer ® (Allium‘MGsmmpkb13 ’ ) is a summercater of ‘ Summer sweetheart ’ that has a tidy thickset use with flowers perched on the leafage rather than rising above like its forerunner . The wakeful purple bloom , in 2 - inch sphere , smother the dark unripe strappy leaves for about a calendar month in midsummer ; modest leaf desiccation was noted sporadically , but heyday masked the damaged tips . In our garden , the neat chunk were 18 inches magniloquent and twice as broad . ( I said it is compact , not dwarf ! ) To me , the two cultivar complement each other more than compete , although side by side , ‘ Summer Beauty ’ looks Thornton Niven Wilder . Summer Peek - a - Boo ® is a versatile mixer ; blousy calamint ( Calamintha nepetasubsp.nepeta , Zones 5–9 ) buffer its sturdy habit , while the vertical spikiness of Russian salvia ( Salvia yangiiand cvs . , Zones 4–9 ) is a wonderful demarcation to its uniformness .

‘Falling Stars’

White - flowered ‘ Falling maven ’ ( Alium cernuum‘Falling Stars ’ ) was a bit of a slumberer to me until it fruit . There is no doubt it is a pretty shape of the typically pink - blossom nodding onion ( A. cernuum)—a character reference to the acute criminal that points the 2 - column inch prime clusters downward in a shower of stars in recent summer . The purple - brown fruits are surprisingly attractive at their meridian , but it is the yin and yang of the virtuous white flowers juxtaposed to the ripening dark fruits that enamor me . The gray-headed - green leave-taking , thicker than those of the mintage , wan to low-cal green with some tip impairment as the season goes along . On my cosmetic scale of 1 to 10 , the grassy leafage land in the heart . There is nothing ill-timed with it ; I just find it less interesting than the bass greens of some other Allium .

‘Windy City’

Protruding white anthers summate sparkle to the dark rose - purple umbel of ‘ Windy City ’ , a standout feature of this 2015 institution . The 2 - inch starburst - comparable , mostly sterile flower head open in early summer and put on a spectacular show for about six weeks . The glossy dark green foliage is peculiarly profuse in the early season ; folio tips may yellow or brown in summertime , although it was not too troubling . ‘ Windy City ’ has a uniform rich habit to 21 inches improbable in efflorescence — while the leaves form a cluster that is 10 inches tall and 30 in wide of the mark . In my mind , I always pair ‘ Windy City ’ with the softer habit of a pot such as ‘ Carousel ’ little bluestem ( Schizachyrium scoparium‘Carousel ’ , Zones 3–9 ) and then reckon how its rose-colored blossom and purplish yield blend with the red - purple , pink , and atomic number 29 tones in the grass stems .

‘Summer Beauty’

‘ Summer looker ’ ( Allium tanguticum‘Summer Beauty ’ ) was developed in the Chicago arena but quickly found fans far afield . Lilac - pink heyday , in 2 - column inch globes , are plentiful in midsummer , describe in pollinators of all stripes for about a month . The shining , cryptical green leaves remain impudently verdant from outpouring to fall , forming shaggy-coated hummock with wiry flower shaft that spring up 8 to 12 in above the leafage . Leave the infertile fruits integral for seasonal interest ; the winter skeletons are delightful etched in hoar or dusted in a snowy drape .

‘Millenium’ Allium

‘ Millenium ’ is the standard by which other alliums are judged ; its popularity has develop steadily since it was introduced at the turn of this hundred . ( The misspelling is unfortunately intentional . ) Each rosy purple flower fountainhead , like a embonpoint lollipop , tops a stout prow to 20 inches tall . Taken all together , the tidy sum of nearly 2 - inch welkin — dozens densely packed on every works — is a fab midsummer spectacle . Dark green strappy leafage , bunch up in generous clumps , are liberal and healthy throughout the summertime and fall even as flower flower stalk turn brownish . The botanic architecture of the flower — resonant of Bertoia ’s sunburst carving — takes on another attribute when the tan yield capsules split up lately in the year . Enjoy the full floral show without worrying about undesirable seedling , because ‘ Millenium ’ is essentially sterile . It is also proving to be cold-blooded hardy to boot . I have translate reputation of ‘ Millenium’—commonly listed for Zone 5 — produce well in Zone 3 gardens in Canada .

Trial Results

Richard Hawke is an expert plantsman and the director of ornamental plant research at the Chicago Botanic Garden in Glencoe , Illinois .

Photos , except where remark : courtesy of Chicago Botanic Garden

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