Starting the Year with a Garden Experiment: Giant Ornamental Onions, Garden Alliums

A Note: It’s 2020 and I am trying to get back into writing again. I’m going to shy away from using the term “blogging”. There is too much weight to the term, and I hope my writing extends beyond my Internet musings moving forward. I am woefully out of practice; yet the only way to do it is do it, so here goes!

Giant Ornamental Onion, most likely Allium 'Globemaster', in the Public Garden in Boston, MA, Summer 2014

Winter Musings

As I sit here the spring peeper frogs are chirping in the night. A sweet breeze blows in through the open window that smells more like the beginning of spring rather than the middle of January. Such is winter in North Carolina these last few years.

Chimonanthus praecox at Juniper Level Botanic Garden

It is this time of year that the Hyacinthus rosettes are pushing through the winter mulch in the gardens of central North Carolina, and one can smell the familiar fragrance of wintersweet, Chimonanthus praecox and C. nitans. These lovely shrubs never seem to be confused by the shifting weather. But back to bulbs.

The Hyacinthus remind me that winter is not a season of death, but of change; and there are rewards for patience: winter/spring bulbs.

I took some time today to wander through a local garden shop (Logan’s Garden Shop) to see what was on offer. I find it important to see what is easily available to gardeners so I can make better suggestions or recommendations when I am asked. It has been a couple years since I’d poked around Logan’s and I was glad for the exercise of it. And glad that my personal rule of not buying plants unless they’re REALLY special was not tickled. I was almost to the door when it was.

“30% OFF ALL BULBS” screamed the big red letters on the bulb bins next to the discount Christmas decorations. Well, crap. I couldn’t help but look.

Tulips, Iris, Amaryllis, and, of course, Hyacinthus….. and Allium! Science brain triggered: I had always wondered how the different giant Alliums performed compared to each other, and here were some of the major hitting cultivars rotting away on the bottom shelf at 30% off. Well, crap, I say; and hand over my money for three different cultivars and a species (summarized at the end) (except for the one I really want one day: Allium schubertii).

Getting Ready for Planting, Bulbs Ordered from Shortest (left) to Tallest (right)

The Great Giant Ornamental Onion Evaluation Experiment

Giant Ornamental Alliums are the sexy garden onions you may see punctuating a mixed herbaceous perennial border or seasonal planter; or as a stunning mass of floating heads, like the planting in the Public Garden in Boston, MA in the summer of 2014 when I’d visited for a walk around the Emerald Necklace (see the blog post and photos here).

Allium in the foreground, Boston Skyline beyond

I agree with Carole Ottesen from the American Horticultural Society that “Alliums don’t get the recognition they deserve” (although her article is a great place to start your “alliophily”). The Great Gardening minds of the modern era all agree they are garden stand-outs, yet they were still languishing on the bottom shelf at Logan’s. In their defense, if you look at charts comparing the different giant Alliums available, like the one in Ottesen’s article in The American Gardener or on Gardenia.net, it is hard to envision their performance differences and it is easy to get bogged down with the idea of “what’s so special about THIS one?”

Article Link: Checklist of Ornamental Allium Species and Cultivars Currently Offered in the Trade (Reinhard M. Fritsch, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung Gatersleben, Germany, 2015)

Hence, why I spend my money: to further our collective understanding of these plants!

So, Let’s Talk About My Garden’s Culture: Adapting How to Grow Ornamental Onions

Alliums, according to the great Allan Armitage (see page 60-72 in the third edition of Herbaceous Perennial Plants aka the Perennial Bible), need well-draining soil, preferably with a lack of heavy clay. Unfortunately, despite the addition of bucket-loads of organic matter, there is still a lot of clay in my garden beds at home. I’ve done my best to create a raised bed that runs deep. Such is the reality of trying to convert modern house foundation into an herbaceous perennial border.

I fertilized the bed a couple weeks ago with Espoma’s PlantTone as a general broadcast (yes, I do a light fertilization with this organic fertilizer in December, as I am fighting some organic matter issues); but I had a sample of Espoma’s Biotone Starter Plus from Plant Delights Nursery, Inc. and thought this was as good a time as any to use it (it is suggested to use it at time of planting). (Find out where you can get Espoma Products here). After some Internet searches, I also found some information about soaking garlic cloves before planting and wonder if that would have worked on Allium.... maybe a future experiment.

The site I chose is in the front of my house in the sunniest bed, but will most likely get part sun un the summer time because of the oaks in the front yard. The bulbs will sit amongst other plants, mainly Salvias and Sedums, and will be side-by-side for easy comparison (see starting summary chart at the bottom).

The timing of my planting is very late. They most likely would have preferred to be planted in October in North Carolina, but I cheated and planted them on this unseasonably warm January day. Wrong time, but right price. Brent and Becky’s Bulbs, which I cannot recommend enough, ships their fall bulbs up to this time of year, so I’ll just fudge my timing with their shipping season!

Rotten Part on Allium 'Gladiator', healthy bulb in background

Unfortunately, because the bulbs did wallow on the bottom shelf for the entire buying season, there were a lot of rotten bulbs in the bags. I inspected each one for rot, and still ended up with one rotten bulb, cleverly hidden by the papery skin. I cut the rot out with sterilized tools and sterilized the region with isopropyl alcohol, as I did not have bleach or hydrogen peroxide on-hand.



Parameters for Evaluation of Ornamental Onions

So, what am I looking for with this little evaluation? I will be looking at when the plants emerge, when the inflorescence stalk starts to elongate, when the flowers open, how tall the inflorescence stalks are, how wide the inflorescences are, how long the bloom period is, how strong the stems are, how the foliage performs, and how long the flower stalks withstand the season after senescence. I might even use them in holiday craft projects next year.

I don’t think I will want to run the evaluation for more than one year. It’s just enough time to see my garden grow through its second season and gives me time to find the best place to move each Allium to next year to highlight its strengths. As gardeners know, everything in the garden is an exercise in patience.

Pretty Packages

A Note: Garden Marketing Has It Easy

A beautiful picture can sell a plant in no time(just check out this “photoshopped” Allium on Amazon Smile); and no time is it more effective than selling bulbs. Papery, dirty skins, some bumps and bruises, and no roots are what await the brave gardener through the plastic, hole-punched packaging. Giant Alliums can be 3-4’ tall and are a garden show-stopper; but on the shelf, they are glorified onions. Que those cute photos of kids and flowers: three of the four packages contained children for scale, and certainly for effect. It is easy to trust that weird-looking onion with a smiling kid hugging the purported giant flower stalk.

The bulbs used in the experiment are from the Netherland Bulb Company. I was especially charmed by the marketing phrase of “Dig. Drop. Done.” You can even go to www.digdropdone.com and learn about bulb culture. It is a marketing tool for bulb companies, but it is an effective tool to help people overcome any hesitation they might have about growing bulbs in their garden.

If you want to learn more about Alliums, or bulbs in general, the Pacific Bulb Society has a great website and is a great society to join.

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Figure 1.1: Table summarizing cultural and marketing points from label that came with the plant, Internet sources, and Herbaceous Perennial Plants (Armitage, Third Edition, 2008)

Plant Name	Origin	Flower Diameter	Flower Height	Resistance (marked)	Light Requirements	Bloom Time	Winter Hardy	Fragrant	Good for Mass Planting	Good for Rock Gardens	RHS Award of Garden Merit Winner
Allium ‘Gladiator’	A. aflatunense x A. macleanii	7-8”	32-36”	Deer, squirrel, rabbit	Full sun	Early summer	X			X	X
Allium ‘Ambassador’	Hybrid A. aflatunense (likely)	6-8”	36-40”	Deer	Full sun to part shade	Early summer	X	X		X	X
Allium ‘Globemaster’	A. christophii x A. macleanii	7-8”	36-40”	Deer	Full sun	Early summer	X	X	X		X
Allium giganteum	Species type	6-8”	50-60”	Deer, squirrel, rabbit	Full sun to part shade	Late spring to early summer	X		X		X