suckering shrubs

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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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.

This lone orange tulip has been blooming for weeks — and doesn’t sucker!

Lessons Re-Learned

Epimedium “Frohnleiten”

Today was my first full day of gardening since last fall (not counting the pruning session in March). While generally happy with things in my little plot, I was reminded of a few truths for those who garden in small spaces (anything less than half an acre).

1. Never plant any shrub that suckers, no matter what sentimental associations it may have, or that it’s a native plant, or that some garden writer you admire spoke highly of it. This includes Oregon grape (Mahonia aquifolium), snowberry (Symphoricarpos albus) and the common lilac (Syringa vulgaris). It also includes the woody perennial (not quite a shrub) Phygelius (also known as Cape figwort). I have all of these, and spend several unpleasant hours every year yanking, snipping and sawing their adventurous shoots. It’s an especially unrewarding task because I know most of the shoots will re-sprout and new ones will join them. It’s too late to remedy my unfortunate plant selection decisions, however, since the original shrubs, now huge and deeply rooted, would require immense labour or dynamite (or both) to dislodge them. Beware of rampaging groundcovers as well, such as ivy and Vinca major. Even the deceptively dainty-looking Vinca minor has thuggish tendencies.

2. If your garden looks like a hopeless mess at this time of the year, do three things before you give up on it: mow the lawn, edge the beds and cut down last year’s old stalks. This will instantly impart the look of a managed garden and motivate you to make further improvements by weeding, loosening the soil, introducing new plants and mulching. Even if the plants occupying the beds are nothing special, this treatment will make them look better. (This applies to perennial and mixed ornamental beds; vegetable gardens are another thing altogether).

3. If your garden is mainly one of tough, drought- and tree-root-tolerant perennials and shrubs along with various bulbs, don’t expect plants with more exacting requirements to do well or even survive without a lot of special attention. They are already having to put up with less than ideal growing conditions and will be no match against tough, colonizing plants such as peach-leaf bellflower, lamb’s ears, toadflax and rose campion. If you can’t provide them with a separate bed, keep an eye out for their early spring growth and make sure they aren’t overwhelmed by their robust, faster-growing companions. I say this after rescuing Thalictrum delavayi “Hewitt’s Double” and even Geum chiloense “Mrs. Bradshaw” (which isn’t generally considered a delicate thing, but is treated like one in my rooty patch). As for my blue poppies (Meconopsis), they have their own slender slice of earth to dwell in, but I wonder if it’s too close to a rather hefty magnolia. They have sprouted out quite well, all seventeen of them, so I have hopes.

Henry Mitchell said, “The life so short, the craft so long to learn. This was said about literature, but it really fits gardening better.” Very true.