Degrees of vigor

One tall growing nandina (Nandina domestica) at the corner of the deck hosts two clematis vines. The large flowered, white ‘Henryi’ (below) is the more vigorous of the two, though it has had to start more or less from the ground up this spring after my wife pruned a large branch that supported it. The nandina and clematis were intertwined so that there was no practical way the two could be separated.Clematis climbing through nandina

My wife asked me several times in recent years to trim the few nandina branches that obstructed the step from the deck (with varying degrees of sternness, but without success). But, pruning would imperil the clematis, so I thought it best just to use one of the two other steps down from the deck. The wisest decision would have been to remove the step and plant something in its place so that there was no decision to make, but my wife was determined, so she took to the nandina and clematis with her clumsy manner of pruning. Now, another stem of the nandina has arched to block the step, and ‘Henryi’ is scrambling along the ground with only a few stems climbing into the tall shrub. It might take another few years for the clematis to regain its foothold in the nandina. Jackmanii clematis in mid May

The purple flowered ‘Jackmanii’ (above) is planted on the far side of the nandina from the step, so it twines safely up the other side. I hesitate to pronounce that ‘Henryi’ is more vigorous than ‘Jackmanii’, but the two clematis have an equal opportunity to clamber through the nandina, and ‘Henryi’ produces dozens more flowers. After flowering both vines recede so that the foliage is barely seen, though the seedheads of ‘Henryi’ are quite nice.Clematis montana 'Rubens' in early May

On the far side of the deck, climbing through five feet of lattice up to the handrail, is the most vigorous of clematis, Clematis montana var. rubens (above). Here, I have planted several vines before the clematis, with a notable lack of success, or perhaps too much success as the vines ran rampant. Five years after it was ripped out of the ground, I’m still fighting pieces of the Chocolate vine (Akebia quinata) that spread in every direction, with dozens of stems racing across the ground beneath the deck and into a tall cypress at the far side. To cover the lattice and rail required a more exuberant vine than ‘Jackmanii’ or ‘Henryi’, and the foliage and flowers of akebia are marvelous, but this was certainly far too much of a good thing.

There seemed no ideal choice to cover this area; all vines were too vigorous or not enough, until I planted Clematis montana rubens. It quickly climbed the lattice and onto the handrail, and it is maintained fairly easily at a proper state of wildness. After flowering, the foliage remains dense and a fresh green through the summer. A few years ago the bushy vine at the top of the handrail was home to a garter snake that seemed unconcerned by its proximity to our living space. I’ll admit to steering clear of this side of the deck for much of the summer, and to pruning the vine reluctantly and with great care. Not that I’m scared of a little snake. Sweet Autumn clematis in early September

Fortunately, the next spring the snake found a new home, and since then pruning the clematis has been much less of an adventure. Pruning the autumn flowering clematis (Clematis terniflora, above) by the driveway presents a different challenge. It was planted to cover a wrought iron fence that borders the drive, but the vigorous vine had other ideas. It quickly leaped from the fence into a tall growing threadbranch cypress (Chamaecyparis pisifera ‘Aurea’), and now the two are inseparable, though this has not proven to be as much trouble as I first supposed. If the clematis began to overwhelm the cypress I could cut it off at the base, and of course the top that is climbing through the cypress would die. But, it has not grown as rampant as I feared, so I take it year by year and I’m not figuring it will be a problem.

If I cut the autumn clematis hard and regularly tied it off to the fence there would be a chance that this vigorous vine could be maintained to cover the fence without jumping over onto every neighboring shrub. I’ve seen this in magazine gardens, but there’s not a prayer that I could keep this schedule, so off it goes into the cypress, where it’s not creating as much havoc as I once supposed.


4 thoughts on “Degrees of vigor

  1. Dear Dave,
    Can you please give tips on how to control well-established bamboo spreading on from my neighbor’s garden into mine and my son’s house next door in Bethesda, MD? Through the years we have had this thick, strong outgrowth hacked down and gallons of RoundUp poured down but it keeps encroaching our spaces-our neighbor cut back some but wants to keep a thick curtain of it; we are desperate and would like something like an iron curtain solution!

    • As you’ve found, you’ll never be rid of the bamboo by just cutting it off. With the main body of the bamboo on the neighbor’s property it will remain vigorous, and it will continue to send shoots onto your property. I’ve seen effective control with a root barrier such as DeepRoot that is sold by many landscape supply internet sites. This comes in various depths and roll lengths so that it can be installed in a continuous length without seams.

      The barrier is installed in a trench with the bottom of the heavy plastic sheet angled towards the bamboo so that when a root makes contact it is deflected up. An inch or two of the plastic is left above ground so that the roots will have to come up out of the ground. You must monitor to cut the roots when they appear above the barrier.

      I know of no other way to dependably control the spread of an established bamboo when digging it out is not an option.

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