Perennials and Annuals – Page 8 – The Garden Professors™

All Right, Linda; I’ll See Your Paraheliotropism and Raise You a Nyctinasty

Amicia zygomeris is a cute little herbaceous thing I picked up on a visit to Plant Delights nursery back in October. For $13, I wanted to be sure it survived the winter, so it’s been in our kitchen garden window, just waiting for spring.

Soon after putting it in the window, I had an “oh no, I’ve killed it” moment one evening. All the leaves were drooping, yet the soil was moist. The next morning, it seemed to be back to normal. The following night, droop city again.

Ah HA! Nyctinasty* at its finest – plant movements to the circadian rhythm. Tropisms are growth responses, while nastic movements are just that – reversible movements. There are other “nasties” out there – photonasty is movement in response to light, hydronasty – water, etc. The classic example is Mimosa pudica – sensitive plant – the little leaves fold to the touch (thigmonasty).

Legumes are particularly prone to this – check out the bean plant flapping its leaves in time-lapse video at the “Plants in Motion” website (U. of Indiana Biology Department). The movement comes from changes in turgor of the cells that attach the leaf petiole to the stem. This spot’s called the pulvinus – think of it as the leaf’s armpit. What do plants gain from this daily spreading then folding of leaves? Folks have been pondering this for centuries. Darwin wrote about it in “The Power of Movement in Plants” (1880). Though the biochemical mechanism has been discovered, I don’t believe any conclusions have been reached as to "why".

Amicia zygomeris in the evening. The common name, courtesy of Tony Avent, is “Gotta Pea". I am not making that up.

*BTW, Nyctinasty is also the name of a pop band from Manila. Must be a biologist or two in the bunch.

Baptisia: Beyond the Blue

The Perennial Plant Association recently released the identity of the PPA Plant of the Year – for 2010 it is Baptisia australis (False Blue Indigo). Various blogs have noted this (including Garden Professor fave Garden Rant) and I’ve read some interesting comments, both pro and con.

True story: I asked for Baptisia at a small rural garden center years ago; the owner said “Don’t have any; but I think I have a Methodist running around here somewheres…” Badda-bump.

Me? I think it is a truly wonderful native perennial. I’ve had great success with it in both Zone 7b and 6a and teach it as a “bread and butter” component plant for the mixed border. As a PPA member, it certainly got my vote on the last ballot (beats the hell out of last year’s Hakonechloa macra ‘Aureola’ – hard to say and even harder to grow in the Southeast).

The great thing about the PPA “Plant of the Year” program is not just in the promotion of that particular species, but that it opens the door for other cultivars and hybrids. Two of my favorites: Baptisia x ‘Twilite Prairieblues’ [sic] and B. x ‘Solar Flare’. Both were bred and/or selected by that delightful genius Dr.Jim Ault, of the Chicago Botanic Garden, and introduced through the Chicagoland Grows program. Pictured are plants that are have only one full year of growth after purchase and planting (nice full gallons to start with; from Saunders Brothers nursery, located in the greater metropolitan area of Piney River, Virginia).

Baptisia x ‘Twilite Prairieblues’ is a cross between B. australis (our PPA winner) and B. sphaerocarpa – a shrubby, tough little guy with yellow flowers. This fortuitous romance yielded quite a jaw-dropping color combination of dusky violet with a yellow keel petal. These puppies are in our campus horticulture garden.

Now take a gander at B. ‘Solar Flare’ – a “complex hybrid, probably open-pollinated” of B. alba (white-flowered), B. tinctoria (yellow-flowered), and B. australis. This is what can happen when a whole bunch of species and hybrids are planted close together (cocktails and/or bees are usually involved). From my own garden:

Buttercup-yellow fades to warm apricot, then to plum – the thing absolutely glows in the late afternoon sunshine. Gosh, I miss summer…

Sigh.

Post-holiday Poinsettia Fatigue

You’ve seen them. The saddest thing ever – a poinsettia, still in its little foil sleeve, tucked into the corner of the doctor’s office/bank/etc. In June.
Photo courtesy of Beth Bonini http://beedrunken.blogspot.com
So iconic, there’s even a rock band in St. Paul called “Dead Poinsettia.”

Every year about this time, I get asked “how do I care for my poinsettia so it will bloom next year?” by friends, students, random callers, and random newspaper writers.

Two words: Chuck it.

Four reasons:
1) Unless you have a greenhouse, you probably can’t replicate the growing conditions that resulted in that lovely, leafy, perfect plant. That poinsettia has been grown under optimal temperature, humidity, fertilizer, and high light conditions. It’s also been sprayed with plant growth regulators – often multiple times, to keep the internodes from elongating. Even with all the breeding for a compact habit, they still want to streeeeetch to be the shrubs/small trees their forefathers were back in Mexico.

2) Day length. Poinsettias are obligate short-day plants, which means they require a long dark period (yes, I know, why don’t they call them obligate long night plants) to become reproductive, resulting in red (or pink or cream) bracts and the little yellow flower-thingy in the center (the cyathia). You can, of course, stick it in a dark room at 5:00 p.m. and remove it to a lighted area at 8:00 a.m., every day for the months of October and November. Until you forget over that long weekend and leave it in the dark for three days…

3) Help stimulate the local “grower” economy. Consumerist, I know, but wholesale and retail greenhouses grow poinsettias to keep their full–time employees working during what is otherwise a very dead time in the ol’ floriculture business. Seldom do these businesses make much of a profit on poinsettia; the plan is to keep everyone busy and generate a little cash flow. Now, some growers/garden centers go above and beyond the usual 6” red point, with unusual cultivars in a range of colors and sizes, hanging baskets, poinsettia “trees”, etc. This has proven to be a great strategy for some enterprising growers.

4) Poinsettia = total whitefly magnet.

In light of the above, I recommend enjoying your poinsettia until the leaves start dropping…then once it reaches the “less than fresh” stage, add it to the compost pile. Next season, go to your local independent greenhouse or garden center and buy a new one. Finally, if you are one of the hard-core, stick-with-it types that has been successfully reblooming the same poinsettia for three years running, congratulations! You have much, much more patience than I do.

Disclaimer: My Master’s research was on poinsettia and the effects of nitrate- N:ammonium- N ratio on growth thereof. Five treatments x 6 replications x 3 cultivars = 90 poinsettias, off of which I picked every leaf and bract to run through a leaf area meter. The latex oozing from the petioles made for a gloppy mess and the whole process took five days. Even 15 years later, I can barely look at a poinsettia without cringing. Pleh.

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Pop Quiz!

Bet you weren’t expecting this on TUESDAY, eh?
Heh, heh.

Situation: these photos are from a grad student project. We wanted to create, observe, and record nutrient deficiency symptoms, so we grew the plants hydroponically in a made-from-scratch nutrient solution, containing everything except one particular nutrient. There were 12 separate batches of solution, one missing each essential mineral nutrient (N,P, K, Ca, Mg, S, Fe, Mn, Cu, B, Mo, Zn – couldn’t exclude Cl as it’s too common in salts). As my research interest is herbaceous perennials, some common perennial taxa served as our victims, er, subjects.

Here’s the set up for the Verbena ‘Homestead Purple’ experiment – rooted cuttings were placed in the little buckets and secured by the lids. The nutrient solution was constantly aerated. For most elements, symptoms appeared between two and four weeks after the start of the project. Symptoms, depending on the elemental deficiency, included chlorosis (yellowing) of old or new leaves, leaf curl, speckling, stunted growth, and in one case, some excessive growth.

Below are results from day 42 of the study. We lifted the lids, hanging-basket style, so we could examine the roots. The control (received a complete nutrient solution) is on the left; Rapunzel there, on the right, lacked a nutrient. Quiz question: What element was missing in this particular case? What made you come to this conclusion?

Hint: If you have a rudimentary knowledge of garden fertility, be it veggie or ornamental, you can probably figure this out. I’ll go ahead and rule out the pesky micronutrients.

(L) Control: received complete nutrient solution (R) Deficiency solution

To Prune Or Not To Prune, That Is The Question…

Dabney rules!

“Dabney! No! Wait!” Just kidding. Dabney Blanton, our lovely and talented horticulturist, knows not to prune the Artemisia in the autumn.

I imagine most gardeners have experienced a frost or freeze by now [exceptions: our Southern Hemisphere readers (howdy to Jimbo)…or anyone in the deeeeep south].

The perennials here in Blacksburg have taken a couple of hits; time to start trimming things back. In the Hahn Horticulture Garden and in my own personal garden, we like to leave perennials and ornamental grasses up as long as possible – gives us something to look at besides mulch, plus the wee birdies enjoy it.

But some perennials just look yucky after a freeze.

Case in point: foliage of the popular perennial Artemisia ‘Powis Castle’ resembles graying Kleenexes, hanging on the tips of the branches. HOWEVER, do not cut this back in the fall. It, like many other shrubby perennials, is sensitive to early winter whacking, in my experience, Buddleia and Caryopteris also fall into this category. Apparently the severe pruning sends a message to the plant to break bud – new shoots can appear and then “zap!” Wait until new buds appear in the spring, and be careful not to cut back too hard. I’ve killed a few that way, thinking I was doing them a favor.

“Cut ‘em back, cut ‘em back, waaaaay back!”

The best resource ever on maintaining perennials is Tracy DiSabato-Aust’s The Well-tended Perennial Garden. I should get kickbacks, as much as I’ve promoted this book! Truly a wealth of info – when should you cut it back, will it rebloom if deadheaded, don’t do [whatever] or you’ll kill it – all broken out by genus. Outstanding!

Eat your veggies! (But not the arsenic, or the chromium, or the lead…)

The last few years have been a perfect storm for the resurgence of home vegetable (and fruit) gardens. Grapevines are trellised along sidewalks, herbs replace the grass in parking strips, and tiny gardens of carrots and lettuce are shoehorned into any available spot. It’s all good – but we need to be particularly careful about what those plant roots might be taking up along with nutrients and water.

1) Contaminated soil. Many urban (and suburban, and even rural) soils are contaminated with heavy metals, pesticides, and/or industrial wastes. Lead is commonly found in soils near roads (from the old leaded gasoline we used to use) or from old lead-based paint chipping away from houses. Arsenic is a very real problem in North Tacoma soils, for instance, thanks to the smelter that operated there for decades. Overuse and incorrect use of home pesticides will leave residues in the soil for years.

2) Contaminated compost and soil mixes. Many of the same contaminants mentioned above can be found in unregulated composts and soil mixes. (More on this topic here.)

3) Treated lumber. The old treated lumber (CCA = copper, chromium and arsenic) is no longer being sold, but it’s out there. These timbers should not be used around vegetable gardens, as they will leach their heavy metals into the soil. Vegetables vary in their ability to take up and store these metals. (More on this topic here.) Likewise, rubber mulches may leach unwanted chemicals into the soil and should not be used around food plants. (More on this topic here.)

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What can you do to avoid these problems? A few things are quick, easy and cheap:

1) Have your soils tested. I’ve mentioned this in an earlier blog on urban soils. It’s the best way to find out exactly what you have in your gardens – the good and the bad.

2) Use only certified composts and soil mixes.

3) Plant in containers if your soils aren’t safe for food. This is especially easy to do with perennial herbs, which can be kept like any other container plant on your deck or porch for years.

4) You can also replace the soil in your vegetable garden. This isn’t quick, easy, or cheap, but is a solution for some people.

Voles are Pickier Than You Think

…and it’s not just the scientifically-proven inverse correlation between the price of the mail-order perennial and likelihood it will get chomped within six months. The prairie vole (Microtus ochrogaster) is notorious throughout central and eastern North America for laying waste to many a well-tended garden. Much of what’s out there in regards to herbivory of ornamental plants (said chomping by deer, voles, bunnies, etc.) is simply anecdotal, yet repeated ad nauseum as fact. So it’s exciting to see some new research in that field, published in a recent HortTechnology journal.

Dr. William Miller’s research focus is bulbs, and his group at Cornell University set up feeding trials with thirty common garden bulb species to quantify the prairie vole’s preference thereof. Tulips topped the list as the colony’s favorite (but you knew that already). In fact, “the voles became accustomed to this feeding schedule, and would vocalize and get excited when we entered the laboratory to prepare the bulbs…”

The voles showed the least interest in daffodil (Narcissus), grape hyacinth (Muscari armeniacum), Italian arum (Arum italicum), ornamental onions (several Allium species) and snowdrop (Galanthus nivalis). These bulbs were evidently high in the sort of secondary metabolites that, among other things, cause plant tissue to taste bad. There were even preferences shown as to different cultivars within each species – they were wild about tulip ‘Apeldoorn’ yet ate half as much of the species Tulipa turkestanica. Note to the vole-ridden…the daffodil ‘Ice Follies’ registered barely a nibble.

Apparently voles love apples more than anything, so the researchers also mixed dried, ground bulbs with applesauce to make them even more appealing. The point of this slightly eludes me, but the take-home message was 1) voles will eat anything except onions when mixed with applesauce, and 2) don’t dip your bulbs in applesauce prior to planting. Now if only Dr. Miller would work on vole feeding preferences by price point…

Source: Curtis, B, D. Curtis, and W. Miller. 2009. Relative Resistance of Ornamental Flowering Bulbs to Feeding Damage by Voles. HortTechnology 19:499-503.

Fabulous Sporobolus!

“Where have you been all my life?!!”

Every once and a while, I come across a plant and simply fall in love.

I am not alone on this particular species, and the bandwagon is getting mighty crowded. Sporobolus heterolepis is the object of my affections…it even has an intriguing common name – Prairie Dropseed. It’s native to much of North America, short of the West Coast. Though most widespread in the Midwest, there are isolated populations in Virginia, North Carolina, and Pennsylvania. It’s even hardy up in the Arctic North (where Jeff and Linda live).

Sporobolus shows off some fluffitude while Echinacea tennesseensis look on in amazement. Author’s garden.

Now on to the juicy description: fine, green foliage forms fluffy mounds or tussocks up to one and a half feet tall and up to two feet wide. I describe it to my students as “pet-able” – one just wants to run their fingers through the flowing locks… The tiny, fragrant flowers appear in late summer form a fluffy cloud above the foliage and wave about on slender stems, even with the slightest breeze. I think the flowers have a coriander scent, have also heard buttered popcorn and vanilla. Seeds form and then drop to the ground around the plant (hence the common name), at which point the birds scarf them up. There is very little actual germination; the species is in fact endangered or threatened in several states (USDA Plants Database). As the weather cools, the fall color can range from bronze to orange to apricot – just gorgeous – and then turns to a tawny buff for the remainder of the winter.

Newly-planted in the Hahn Horticulture Garden at Viginia Tech – check out that fabulous fall color!

As with many prairie natives, this a very tough character once established – puts up with lousy soil, little rainfall, and is definitely drought-tolerant. We’ve added more than 100 of them to our campus meadow garden. At my favorite public garden, Chanticleer (Wayne, PA), they’re planted in huge drifts and are managed in the “natural” way, with controlled burns in the early spring.

Doubt you’d find it at a big box store, but it should be available at an independent garden center near you! Please note this one of those species that does NOT look very exciting in the pot, especially in the spring (green, grassy, that’s it). But give it a season or two in your garden and…[cue romantic violins…].