Allium Fever

Ornamental onions are hot patooties.  From big, bold, purple globes to small pink half-moons, there is no end to ornamental onion-y goodness out there with 30+ species and cultivars in the trade.  There’s no substitute for ornamental onions in regards to architectural drama – the perfect geometric foil to wispy grasses, floral spikes, and umpteen daisy-thingies.  The seed heads from the sturdier species will persist and add interest to autumn and winter perennialscapes (not sure if that’s a word).

Not one but TWO cultivars of Allium on the cover of the fabulous new Chanticleer book…

All are members of the Allium genus, just like those onions sprouting in your kitchen counter veg basket – hence the deer- and small mammal- resistance factor.  However…there are some issues.

  • Can be short-lived.  I have first-hand experience with this – plant, enjoy for a year or two, then…where did they go?
  • Bloom time is rather vaguely defined.  Most catalogs list “early summer” or “late spring” for most cultivars.  But if you want continuous purple orbs, what’s the order of bloom?
  • Can be expensive. Bulbs for some of the mammoth “softball” sizes will set you back $5-$7 each (the bulbs themselves are huge).  This is of particular concern due to the first item.
  • Foliage failure.  For some of the largest species and cultivars, the foliage starts to die back around (or even before) bloom time.  Not a lot of time to put the necessary energy back into that big honkin’ bulb.

We already have a multi-year lily perennialization trial going in conjunction with Cornell and some other institutions.  I thought I might try the same thing with Allium.

Student worker Lauren, after a long day of taking data on a gazillion lilies.
Student worker Lauren, after a long day of taking data on a gazillion lilies.

Unfortunately, I had this bright idea in November – well into the bulb-ordering season.  I tried to compile as complete an inventory as I could, ordering from several vendors.  Ended up with 28 species and cultivars – as much as the space prepared (check out that nice soil!)  could hold, at our urban horticulture center near campus (Virginia Tech is in Blacksburg, USDA Zone 6, about 2000′).  We put five or seven bulbs (depending on size) in each plot, and replicated the whole thing three times.

Ready to plant!
Ready to plant!

We’ll take data over the next three years on time of emergence, bloom time and duration, foliage duration (have a nifty chlorophyll meter that can help quantify that), some growth measurements, and perennial tendencies (or not).  My hope is to end up with a really specific chronology of bloom times plus life expectancy.  Yes, this was just a patented Holly wild hair; luckily I had some general funds to cover it. But I do think our little onion project will be of interest to more than a few folks, whether professional landscape designers or home gardeners.  I know I’m excited to see the results ($30 for five bulbs – yeek)!



The Handy Dandy Dibber

A dibber, also called a dibbler (the garden tool, not the small nocturnal marsupial),  has many uses in the garden and greenhouse.  It also offers the opportunity to announce your intentions of dibbing (or dibbling). I’m a huge fan.

For example: just planted the last of my fall bulb purchases.  One of packs remaining was Allium unifolium, left over from installing our Allium field trials. (28 species and cultivars – woo! Beats doing research on soybeans or something.)  These little bulbs are about the size of nickel – even the smallest hand spade is overkill. I think I’ll just grab the dibber!

dibsandalliumHSFor the uninitiated, a dibber or dibbler is simply a very sturdy, pokey thing, with a nice ergonomic handle.  To use, simply scatter bulbs (never, ever in rows)…  scatterandpokePoke and plop. Went about 5″ to 6″ deep for these wee bulbs. Goes really fast once you’ve honed your dibbing skills.

holesAs a bulb-planting strategy, I like to leave them all uncovered until I’ve got the whole batch situated.  Then make like a squirrel and cover the bulbs!

doneVoila.  Done in 60 seconds! Though I’ll probably forget where I planted them within 60 minutes (which does make for a pleasant surprise come spring time – “Oh look! Alliums!”)



It’s Spring-o’clock Somewhere…

We’re supposed to get an inch or two of snow tomorrow.  It was 75 degrees last week. Typical schizophrenic spring weather. But spring was already in full bloom a few weeks ago in Dallas, Texas.  Our group of Virginia Tech floriculture faculty and grad students visited for the National Floriculture Forum, a meeting of researchers and educators. It was organized by Texas A&M and hosted by the Dallas Arboretum, home of uber-horticulturist Jimmy Turner.

The Arb was right in the middle of their “Dallas Blooms” festival – they plant half a million spring bulbs each year for the most amazing show this side of Keukenhof.  I’ve never been a huge tulip fan, but somehow came back with a gazillion photos. You just couldn’t help it. It’s a beautiful display garden; don’t miss it if in the area.

Imagine 60+ acres of this. My retinas were burning. But in a good way.

A cute Fosteriana-type tulip, oddly named ‘Zombie’.
Note the use of pecan hulls as mulch. Results in the biggest, fattest squirrels you’ve ever seen.

I’ve seen some interesting art in public gardens, but this is a new fave.
Probably there’s a deeper meaning behind it, but basically it’s a man and woman snogging in the tulips.

Big squirting toads, with list of safety rules on what one shouldn’t do to/with the toad.

Jimmy said the place would be crawling with brides and babies by afternoon, and he was right. That’s what he gets for creating such a photogenic garden. Couldn’t swing a fat squirrel without hitting one or the other.

Potted plants…really potted

A week or so ago my new friend Doug wondered about some gardening advice on the radio: would adding vodka to paperwhite narcissus make the flowers less “floppy?” The explanation he’d heard was that alcohol would burn the roots and reduce stem growth. Then today I received an email newsletter with the same intriguing information. This newsletter referred to a 2006 article that appeared in HortTechnology as the source of this information.

The study by Miller and Finan has generated a lot of interest in the gardening community, especially this time of year as people get ready to force bulbs for indoor blooms. Unfortunately, that enthusiasm isn’t evident among researchers. Neither the original authors nor any other researchers have continued this work; the HortTechnology paper has never been cited in any subsequent publication.

This is unfortunate – because inquiring minds want to know WHY alcohol causes narcissus stems to be shorter. Miller and Finan hypothesize that it’s simply an osmotic effect and allude to preliminary data that support this, “but additional work will be needed for confirmation.”

So I’ve looked into other scientific articles about ethanol and roots for insights into this phenomenon. There’s nothing on narcissus, but others have studied trees, forsythia, tomato and barley reactions to root-zone ethanol. In all of these cases, exposure to ethanol resulted in reduced root growth, decreased water uptake, and reduced leaf transpiration.

How does this translate to shorter stems and leaves? A reduction in water uptake and movement through the plant – that is, from roots through the stems and out of the leaves – can reduce movement of growth regulators like cytokinins from roots to stems and leaves. It can also mean that the plant contains less water and is less turgid as a result. Both growth regulators and cell turgidity are important in cell division and elongation. Reduced cell expansion will cause stems and leaves to be shorter and/or smaller as a result. This same phenomenon can be seen in plants grown under saline or droughty conditions: these plants are always smaller than their normal counterparts.

So what your grandmother used to warn you about is true – alcohol WILL stunt your growth!

Baffling Daffs

It is daffodil season in the Northern Hemisphere, hurrah!  May their blooms shoo away the gray of winter! It is also the season where everybody and their mother writes something about the wonders of the genus Narcissus, so figured I’d join the fray, but with a bit of a chip on my shoulder…

Miss ‘Barrett Browning’ in the Hahn Horticulture Garden at Virginia Tech

I recently read YET ANOTHER article warning against mixing daffodil stems in with other cut flowers due to “harmful effects from the sap”. If stems are conditioned, that is, placed in warm water on their own for 12 to 24 hours, it’s supposed to be o.k. This is repeated in everything from floral arranging manuals to gardening articles, but they never say what exactly causes the problem. So I’ve combed through many resources, to find a specific study backing this up and identifying what compound is responsible.


1) There is such a thing as “daffodil picker’s rash” which has been reported in the journal of Contact Dermatitis  (Julian and Bowers, 1997).  The authors attribute this rash to the “crystals of calcium oxalate in the sap, in conjunction with alkaloids, [which] act as an irritant, and also cause the characteristic sores.”  Duly noted.

2) Said calcium oxalate crystals are found throughout the daffodil, in the bulb, stem, sap, flowers, etc. Micrographs show that these crystals are needle-sharp, and apparently very painful (I have not gotten up the nerve to give them a nom).  This is why deer and bunnies will not eat your daffs.

3) The list of alkaloids is fairly extensive (as with many other members of the Amaryllidaceae family), including masonin, homolycorine, and a real nasty one, narciclasine- which disrupts cell division (meiosis) much like colchicine.

4) Are daffodils poisonous? Yes. If you (or your cat) hunkered down and consumed an entire bulb, problems would ensue. But the calcium oxalate crystals are, perhaps, nature’s way of convincing you (or Mr. Twinkles) that this is not a good idea.

So is there really an effect and if so, what makes daffodil sap deleterious to the other flowers in the vase?  The study “Effects of Daffodil Flowers on the Water Relations and Vase Life of Roses and Tulips” by W.G. van Doorn appeared in the Journal of Horticulture Science. Dr.van Doorn found the mucilage (sap) was indeed to blame, with just one daff shortening the vase life of both the tulips and roses by almost half.  But what component?

He split out the alkaloid fraction and the sugar fraction of the sap, and then added them as individual components to the vase water.  He drew different conclusions as to the cause: the research indicated that the effect in roses is mainly due to the sugar and polysaccharide fraction of the mucilage stimulating bacterial growth. This clogged the rose’s vascular system resulting in bent neck. You’ve seen this before – the bud, yet to open, flops over, never to recover.

These same sugars didn’t impact the tulips negatively but the alkaloids sure did. Even touching the sap to the tulip foliage produced a yellow spot.  He was not able to distinguish which of the six alkaloids detected were responsible, but at least narrowed down the cause ( sounds like a job for a grad student!).

So there you have it. I feel better. Am off to pick a few daffodils (very carefully) to brighten my office.