Mahonia aquifolium

Misled by Experts?

When things work out badly, there is a tendency to blame someone else, often those who give advice.

Quotation:
“Gardening is a vocation like any other—a calling, if you like, but not a gift from heaven. One acquires the necessary skills and knowledge to do it successfully, or one doesn’t. The ancients gardened without guidance from books, by eye and by hand, and while I am a devotee of gardening books and love to study and quarrel with them, I don’t think they are a substitute for practical experience, any more than cookbooks are.”
Eleanor Perenyi, Green Thoughts: a writer in the garden.

At the very least, gardening advice may contain mixed messages.

Case in point: Italian arum. Henry Mitchell, a garden writer I admire, praised it but omitted to mention its smelly flowers and spreading tendencies. The Royal Horticultural Society gave it an Award of Garden Merit, but now I learn it’s labelled an alien invasive here in southern Vancouver Island, and in Washington State as well.

Snowberry (Symphoricarpos albus) and Oregon Grape (Mahonia aquifolium) are both touted as gardenworthy native plants, deer- and drought-proof, BUT both sucker like mad and aren’t suitable for small gardens unless situated so sucker control is doable. I think the Mahonia is also an RHS award winner.

One web site describes Mahonia aquifolium as growing 3 to 6 feet tall with a 2 to 5 foot spread. Hah! The oldest parts of mine are more than 10 feet tall, and I’ve dug up their suckers several yards from the parent plant. The site makes casual mention of suckers, recommending that they be removed if one does not want the plant to naturalize (which means “take over”). It claims the plant needs “moist but well-drained” soil. Not true; it will grow in bone dry soil once established, but it does need good drainage.

When I was making this garden in the early 1990s, the internet was just getting going. I did my plant research in books. If an author conveyed their enthusiasm about a plant in eloquent prose, I was convinced. Especially if the plant was native to my region; native plants are always good. So I can’t blame the experts entirely. It’s quite possible I skimmed over or ignored mentions of these plants’ less desirable qualities.

My advice: before rushing out and planting something, especially a tree or shrub, ask gardeners in your area about their experiences with it, and/or observe the plant in nearby settings if possible. As Eleanor Perenyi said, there’s nothing like experience, but the experience of digging and sawing out a thicket of Mahonia isn’t one I wish to repeat.

A search through my archives reveals that I’ve whined about Oregon Grape and Snowberry nearly every spring for years. I hope this will be my final post of this type. But any gardeners contemplating these shrubs as additions to a small garden, take note!

On the plus side, I’ve finished most of the ~~amputations~~ pruning projects I described a few weeks ago. The root-cutting saw I bought last year had a good workout and lived up to its billing. It powered through some fat Mahonia stems and roots quite impressively.

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Managing

Nearing the bottom of Bin #2

One of the big garden jobs that actually got done in May was Compost Management. This means: 1) Shovelling out the remaining bit of finished compost from Bin #1 (the smaller one). 2) Building a new heap from all the accumulated stuff in Bin #2 — cut down perennial stalks from last summer, last fall’s leaves, old stalks cut down in fall and spring cleanup, and fresh material from recent tidying jobs. All this is layered and arranged in Bin #1, new material on the bottom, old on top, dampened down, and allowed to mellow until next spring. 3) Meanwhile, new stuff will be deposited into Bin #2, where it will pile up through the rest of the summer, the coming fall, until next spring. Whereupon the job will be repeated.

Bin #1 full, #2 splendidly empty

What happened to the former contents of Bin #1, i.e., last year’s compost? Most of it was distributed around the garden this spring with supplements mixed in to make a “feeding mulch.” Some was used to make soil for potting up tomato plants in May. The last wheelbarrow full is sitting in a neat pile near the shed, until needed for mulching or mixing.

At the weary end of forking and shovelling the half-baked brown stuff (mostly leaves and fern fronds), I discovered a tool I’d been missing — a three-pronged cultivator with a wooden handle. I must have inadvertently dumped it into the heap along with a bucketful of garden debris. It doesn’t show much damage from its year in the heap, only a bit of rust. Painting the handle red might be a good idea to avoid reburial.

Watering anxiety and rain envy begin now. Our very dry May hasn’t had visible effects on plants here, but it has affected the gardener. I’m apprehensive about the next two or three (maybe four) months. If the trends of the past few years continue, we may see almost no rain until late September. Water from the end of a hose is a poor substitute for rain, which has the great advantages of even distribution and no cost.

For the past month, whenever I exit the front door of my house I’ve been getting a visual treat from the ceanothus or California lilac, its branches almost solid with puffs of tiny flowers of a magical blue. They’re really popular with all kinds of bees.

Years ago, I bought a packet of California poppy (Eschscholzia californica) seeds. They were called “Thai Silks” and featured colours other than the standard bright orange. I recall one plant, long gone now (they’re annuals or short-lived perennials) with double lemon yellow flowers. Even now, some of the unusual colours persist — cream, cream with pink or red flushes, different shades of pink, and extra-dark orange. It’s a surprise every year to see what colours show up.

I don’t know about other gardens, but here plants fall into three categories — those that struggle and eventually die, those that grow ferociously and try to take over, and some that prosper in a quiet, reliable way. Guess which one is predominant. Well, to be fair, the pushy plants attract more attention so it seems there are more of them. But they do need to be managed, i.e., pruned, restrained, or dug up.

The next Big Garden Jobs on the agenda involve pruning. That lovely ceanothus has a habit of growing sideways, which means it ends up overhanging walkways and getting too friendly with people who use them. And the Oregon grape you can see behind the ceanothus is frighteningly vigorous. I wrestle with it every year, trying to keep it shorter than 12 feet and digging up suckers. It’s almost too late, though; I should have tackled it right after it finished blooming in April. Well, there’s always next year…

Allium christophii blooms and Phlomis foliage

Allium christophii and Phlomis fruticosa foliage

When I’m not deadheading, edge-clipping, checking on recently-planted things that might be getting overwhelmed by the incumbents, or lugging cans of water around, I do stop to admire plants that are performing as expected.

Ornamental grass Stipa tenuissima, Penstemon blooms and Lambs' ear stalk

Ornamental grass Stipa tenuissima, Penstemon glaber flowers, a lambs’ ear bloom stalk, and a few remaining forget-me-nots.

Clematis “Pink Fantasy”

Friends or Enemies? No, Just Plants.

“Peach-Leaf Bellflower, Garden Enemy #2” is one of my most-viewed posts. It was written in a fit of pique after I stabbed a hyacinth bulb while engaged in a heavy session of digging up peach-leaved bellflower (Campanula persicifolia) that had spread by runnng roots. I have since relented in my harsh judgement of that plant.

Partly it’s because I’ve decided there are plants even more apt to spread and harder to control. To wit: Oregon grape, snowberry, periwinkle (both Vinca major and V. minor), achillea, bloody cranesbill (Geranium sanguineum), and certain daylilies. I’ve fought more desperate battles with these than I ever waged against the bellflower (which is rather attractive just now, in its first flush of bloom).

It’s dumb of gardeners to blame plants for being themselves, bestowing upon them unkind epithets such as “thug” or “garden enemy.” (Not that the plants give a damn). I’m the one who decided to plant peach-leaved bellflower, Oregon grape, and snowberry in my garden, thinking them good choices because they are drought-tolerant, or native species, or both. Thing is, they succeed in our local conditions precisely because of their deep-rooting, runner-producing tendencies.

A recent reading of Noel Kingsbury’s excellent book, Garden Flora, gave me a new perspective on this — grouping or classifying plants by ecological habit, as well as by habitat or anatomy.

In looking at the longevity and persistence of plants, some are called “clonal” and others “non-clonal.” The first group includes those that spread by rhizomes, roots or stolons, and others that stay in one place but increase in size. Non-clonal plants are generally short-lived, but produce lots of seeds to ensure persistence. Both types are represented in my garden. The spreaders and seeders are the ones that give me grief, and on the whole, the seeders are easier to deal with. Deadheading is a lot easier than digging up Mahonia roots, let me tell you.

Kingsbury says the non-clonal plants tend to be pioneers, moving into an area and flourishing briefly, only to be supplanted by clonal competitors, whose roots, whether running or expanding in place, allow them to dominate their environment.

Learning about the science of things is a good antidote to the human tendency to personify. Plants don’t run or produce zillions of seeds just to bug gardeners, but as a survival technique. If gardeners were aware of these habits before they introduced plants to their precious patches of earth, much physical exertion and gnashing of teeth could be avoided, or at least minimized.

It would be helpful if writers of advice for gardeners included this aspect of plant performance in their writings. I’m sure if I had read something like “this is a tough, drought-resisting native plant, but gardeners should be aware that it spreads vigorously in conditions that meet its needs,” I would have avoided some plants, and situated others more carefully.

Beguiled by fervid descriptions of a plant’s flower colour, reliability, or the fact that it’s a native adapted to local conditions, I have rushed out, bought one or more, and installed them in my small patch of land. They took hold and flourished. Fast-forward a few years to see me whine and swear at colonizing shoots metres away from the original plant, often in the middle of some pampered darling that’s trying to make up its mind as to whether life is worth living. By this time, of course, the original plant has grown large enough that removing it would be a major project of the back-breaking variety.

The gardener mutters and swears. The clonal plant clones. The planet rotates. The gardener digs, chops, mutters, and swears.

Innocents, take note!

The Hori-hori Knife — essential weapon for battling suckers.

So Long, Sucker! But There’s (Another) One Born Every Minute.

My garden is full of them. Suckering shrubs — Oregon Grape (Mahonia aquifolium), Snowberry (Symphoricarpus albus), and common Lilac (Syringa vulgaris) — the last now in glorious bloom. There’s a suckering tree as well — the dreaded Tree of Heaven (Ailanthus altissima), known around here as the Tree from Hell.

Common lilac in bloom

The standard advice for dealing with suckers is to trace each one back to its point of origin on the parent shrub and tear, not cut it off. Tearing has a lasting effect, apparently (similar to plucking rather than shaving unwanted hair). Remove soil if necessary to accomplish this, the advice says, helpfully. Well, that’s fine if the shrub and its suckers live in solitary splendour with nothing around them except grass, possibly, but what do you do when the shrub is surrounded by perennials, bulbs, groundcovers, and even other shrubs? “Removing soil,” otherwise known as digging, isn’t really an option in a densely-planted mixed border, especially if a multitude of suckers has popped up several feet away from the parent plant.

The best advice is don’t plant sucker-prone shrubs to start with, no matter what other qualities they possess. So what if they’re native plants? Both Mahonia aquifolium and Symphoricarpus albus are native to my region, adapted to local conditions and trouble-free. They settled in happily here, sending up shoots with enthusiasm over the years. If I had several acres at my disposal and wanted a natural garden that could be left to its own devices, these plants would be great, but on a 50 x 120 foot lot (that also accommodates a house, garage, driveway and paved walks), planting these and other suckering shrubs guarantees either a wilderness effect or a gardener ready to nuke everything with herbicides and start over again. (I wish I could go back in time and give my younger self this lecture).

So — with the “nuclear” option not practicable, and not being ready to move to another patch of land, what do I do about suckers (besides curse and wail)?

In theory, it would be good to create a cordon sanitaire around sucker-prone shrubs, clearly defining a no-go area for each one. No suckers beyond this point! This would be done with a sharp spade, plunged into the ground all around the offending shrubs, at a distance of several feet. The process would have to be repeated at least twice a year, similar to edging a bed or border. Given the brutality and intensity of the work, there could be no plants of value growing in this foot-wide space. But setting a border makes the situation seem less chaotic and limits the space in which sucker removal is absolutely necessary.

Any suckers detected outside the cordon sanitaire would (in theory, at least) be removed immediately using minimally invasive techniques. First, the good old yank-by-hand method. Sometimes it works. More often than not, the sucker snaps at ground level, leaving a stump that’s hard to hold on to. Or the bark strips off, resulting in a little whip that’s too slippery to yank. A tool is then needed. For small young suckers, a dandelion tool works. Thrust it parallel to the sucker until it cuts and the sucker releases. (But remember, cutting isn’t as effective as ripping). For older, thicker suckers, a small, cheap, pointed saw of a type designed to cut gyprock (sheetrock) works fairly well. Like the cutting-with-spade procedure, this search and destroy operation is best repeated at least twice a year. Three or four times is better, especially in regions with mild winters. Constant vigilance is best.

I have a fleeting hope that if I follow these processes diligently, the shrub will get the message, “None of your suckers will live to see the light of day!” and stop sending out the roots from which suckers grow. But somehow I doubt that will be the case.

A forest of Oregon Grape suckers

In reality, the years have a way of slipping by, and the gardener is not as diligent as necessary. In my garden, it’s too late for the cordon sanitaire. Roots of Oregon grape and snowberry have spread far and wide. For the past several days I’ve been engaged in an epic struggle with an enormous Oregon Grape (Mahonia aquifolium). I removed three large stems (diameter 2-4 inches at the base) and reduced the remaining plant’s height from about 12 feet to 8. Worst of all was pulling, digging or cutting (sometimes all three) a multitude of suckers, ranging in size from less than a foot tall and 1/4 inch in diameter to 4 feet and 1 inch diameter.

Oregon Grape prunings (right) and suckers (distant left)

Typical Oregon Grape suckers

The “after” picture: remaining Oregon Grape visible behind the Ceanothus

I cherish no illusions that the suckers are really gone. Their stubs and deeply buried roots are still there. They will no doubt rise again, like a bunch of prickly green zombies. Really, the best way to avoid suckers is not to plant suckering shrubs. And if any plant shows suckering tendencies, rip it out.