Plant of the Month – October, 2007

Allium canadensis var. mobiliensis
Allium canadense ‘White Flag’

At a glance
Latin Name: Allium canadensis var. mobiliensis & Allium canadense ‘White Flag’
Common Name: Ornamental Onions
Flowers: Small 1″ globes of white
Foliage: spiky and upright
Mature height: 18″ in flower
Hardiness: Perennial zones 5-9
Soil: Acid to alkaline
Exposure: Full sun
Water usage: Low
Sources: Mail Order

It’s winter and you’ve been cooped up inside due to the cold, but your gardening glands are still a-workin’! What to do? Well, do what any self-respecting gardener worth his compost does: Shop the catalogs and the internet! I know I do. I swear, those companies know just the perfect week to send them out – they always seem to land in my lap during the most inclement weather.

Mail-order gardening used to be the bastion of half-dead mis-labeled plants that were unsuited for any but the most perfect environment. Not nowadays! Now, it’s the home of unique and well-suited plants to any climate. Seems like our local nurseries these days want to stock only those plants that they can buy by the millions, and that look perfect in a 4-inch pot. If it doesn’t flower when it’s 3 inches tall, they don’t stock it. A mark of a true gardener is that hunt for the weird, different and unique. OK, so I get a little carried away, but I really like finding new plants for Texas. Luckily, now I get paid for it!

So, now that I’ve been ranting, maybe I should tell you about a plant I discovered by accident. I’ve always been in love with alliums (ornamental onions). With therapy and many years of wasted money, I’ve given up on the really big ones. You know the ones of which I speak, those basketball-size beauties that always grace the cover of bulb magazines. Forget them. They won’t live here, not now, not ever, and yes, I’m bitter. If I ever leave the Dallas Arboretum, it will be to go somewhere I can grow fuchsia, tuberous begonias, and those head-size alliums. So why am I talking about alliums? Because there are some really great perennial varieties with smaller flowers that perform perfectly in Texas.

Many years back, I went to Canada for a Perennial Plant Conference and one garden I visited had this white-flowered allium everywhere. It looked like white-flowered chives on steroids – bright ping-pong-size balls on tough stems in clumps, in rows, in pots. And, as usual there was no label. (You want to drive me nuts? Show me a plant that I must have without a label and I guarantee you I’ll know everyone in the garden in five minutes.)

So after much searching, chatting, talking, begging, cajoling, offering up of my soul, someone actually knew what it was! Allium canadense var. mobiliensis, a Texas native wild onion, which is usually considered a weed! I was confused! The onion I knew by this name made huge amounts of tiny bulbs instead of flowers and would quickly take over your yard. If you’ve ever mowed your yard and it smelled like onions, you have it. Well apparently this is a flowering form that doesn’t make the bulbils, therefore no taking over of your lawn.

I begged well enough to get some to bring home, and learned the fun of dealing with American customs officials. That little Texas native onion I brought from Canada years ago is now perfect and ready for dividing (and no, you can’t have any, buy your own). You can find them at They have an even better variety called ‘White Flag.’ (You can tell them you heard about them from me. Maybe I’ll get a better discount for the trial program so I can buy more!)

Now for the stuff you’ve really been reading for. This bulb forms tight, 18-inch-tall and wide clumps of typical glossy green onion leaves. In late spring, the 2-inch, creamy-white flowers appear and last for at least 4 weeks. Soon after flowering when the weather gets really hot, it takes a nap until the first rains of fall, when it re-sprouts. Isn’t it amazing how native plants have adapted to our “challenging” climate?

This ornamental onion grows and flowers best in full sun and its only soil requirement is good drainage. As to watering, don’t worry about it. This one is tough and can stand up to cactus-like conditions with no problem. Just remember, you probably won’t find this on local nursery shelves, so you’ll have to do some web surfing or mail-order. When you do finally get one, remember that its one of those “ugly duckling” plants. Not so pretty in the pot, but gorgeous when it grows up (kind of like your sister’s kid? Just kidding!)

If you would like more information about the Dallas Arboretum Plant Trials visit our Web site at

About the author: Jimmy Turner is the Director of Horticulture Research at the Dallas Arboretum. For more plant profiles by Jimmy, subscribe to Neil Sperry’s GARDENS Magazine.

The Arboretum is getting ready for the largest outdoor floral festival in the Southwest: Dallas Blooms! More than 400,000 spring-blooming bulbs have been planted, including tulips, daffodils, Dutch Iris and hyacinth. Pansies and violas have been planted on top of the bulbs, creating a spectrum of color during the winter months while the Arboretum waits for the spring blooms. This year’s theme of Dallas Blooms is “Flower Power,” celebrating the 60s and 70s with many activities, concerts and displays. Check for more details.

Join us this spring in the garden and let us grow your mind! For a full calendar of classes and descriptions, or to register for classes, go to, and click on LEARN, or call (214)515-6540. Join us this spring and let us bring nature to life for you!


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2/10 Reigning Roses
2/10 The Paper Trail: Handmade Paper
2/10 Photo Creations
2/17 For the Birds: Bird Bath
2/17 Tons of Tomatoes
2/17 Rain, Rain, Come My Way
2/17 Plants that Beat the Heat*
2/24 Creative Floral Container
2/24 Water Gardening Basics
2/24 Wildflowers Wonderland

Posted by Neil Sperry
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