Removing Invasive Plants from Stanley Park

   Vancouver, British Columbia, Canada

Home   English Ivy   Blackberry  Lamium, Periwinkle, Laurel   Bindweed, Knotweed   Obstruction   

Yellow Lamium - done
Lesser Periwinkle - done
English Laurel - done
St. John's Wort - done
Holly - never

Yellow Lamium - all cleared

Lamium (or Yellow Archangel, Lamium galeobdolon) is used by gardeners as ground cover because it spreads so well - exactly the characteristic that makes it so dangerous in the wild. Lamium is very hard to remove and requires repeat visits for years to complete. It should be given a top priority for clearing.

It grows from a small ball below the surface that is firmly anchored by many tiny roots. It is best to partially loosen the soil with a cultivator before working your fingers down below each plant's root-ball before pulling. Take away as much soil as comes up. Plants spread with very fine horizontal stems above-ground that root many feet away. Lift the pulled plant carefully in order to feel the tug of any runner. Most times it will break without your noticing. When the leaves are damp they are very difficult to tell apart from buttercups because the light reflecting from the buttercup's indents gives the same impression as the lamium's variegation. It is easiest to distinguish in mid March when it grows higher faster than the buttercups. The April flowers are a dead give away.

Stanley Park invasive plants - lamium..Stanley Park invasive plants - lamium mat

For removal of solid mass mono-culture, it is easiest to use a sharp flat-bottomed turf shovel to remove the top inch of soil completely - getting all the root-balls and horizontal stems at once. I borrowed one from near-by road crews who kept their shovels nicely sharpened. Six years after clearing the spot at Hollow Tree, new plants are still showing up - despite regular checking. These plants must be coming from seeds that have remained viable for many years.

Do NOT throw pullings onto any compost pile. They do not die. They colonize the whole pile - migrating to the new top when you turn the pile. It is best if they go into the garbage. The only alternative is to 'rot' them in place covered in plastic - a process with its own problems.

The cultivated gardens adjacent to the wild west of Stanley Park are rapidly being taken over by this plant. Starting at the park boundary , the plant beds covered in Lamium are getting closer and closer with every year. And each plant bed quickly progresses from a few weeds to being completely over-run. Yet the gardeners do absolutely nothing. NOTHING. It should be the gardeners' priority.

Stanley Park invasive plants - sites cleared of Yellow Lamium and Periwinkle

Lesser Periwinkle - all cleared within my territory

Periwinkle (Vinca minor), another gardeners' ground cover, is much easier to deal with. If there are no other plant species mixed in, then the periwinkle can be easily pulled up by clumps. Doing this in the summer dry period allows any remaining plants to die from desiccation in the disturbed soil. If there are other plants among the Periwinkle then it is better to wait for the winter die-back. Pulling in wet weather will mean that some plants remain viable, but they can be easily found with a few repeat visits. Pullings will compost if simply left in a pile and turned a few times.

The only patch, now cleared, is shown in the map above. A patch outside my area, down the switchbacks from Prospect Point, has been brought to the attention of SPES. So far they have decided to not clear it.

Stanley Park Invasive Plants - periwinkle flower..Stanley Park invasive plants - periwinkle leaves

English Laurel - all necessary plants cleared

English Laurel (Prunus laurocerasus) is a foreign plant but not invasive - at least not in Stanley Park. I have spotted nine individual plants in the wild west of the park. Four were full grown at about six or seven feet tall in different areas. One has a trunk thick enough to be a tree. Yet only one of the small plants was close enough to possibly be an offspring. The others were widely dispersed. The remaining very large 'tree' does not flower, so I feel it is safe to leave.

Stanley Park Invasive Plants - English Laurel leaves, prunus laurocerasus..Stanley Park invasive plants - English Laurel, prunus laurocerasus

In the wild these plants are not the bushy hedges you see in town. They have a limited number of long stems. The alternating leaves twist to all face flat upward. The leave are thick and glossy. You can tell the difference from Salal by Salal leaves' slightly wavy edge. Lots of websites warn about the leaves, stem and roots of Laurel plants causing rashes when touched. I don't know how serious that all is, considering the widespread use of the plant as garden hedges. I have pulled up the small plants by hand, and had leaves brush my face, without any effects.

For small to medium size plants, the roots radiate just under the soil so no gloves or tools are necessary. Just grasp the stem and pull. It takes about a minute. For larger plants there will be one thick root often running sideways. It is easy to cut through with the keyhole saw used when clearing Blackberries.

Stanley Park invasive plants - sites cleared of English Laurel

St. John's Wort - all cleared

Gardeners love the St. John's Wort (Hypericum perforatum) long-blooming showy flowers. They deadhead the blooms in fall dumping them in the back of their trucks. It is clear from the plant's pattern of occurence in the woods, that its source is seed heads falling off the trucks. None of the isolated plants shows any indication of spreading much less being 'invasive'. Only one plant in full sun grew with vigor. All were right beside the trail.

Stanley Park invasive plants - St John's Wort

Single plants need no tools to clear. Simple grab the stem and pull. The one bigger clump required a cultivator and/or keyhole saw to loosen the roots.

Stanley Park invasive plants - sites cleared of St John's Wort

Holly

There are tons of Holly plants growing through the wild west of the park. But they never seem healthy or vigorous. They never form trees. So I conclude they are not invasive - they don't out-compete other native plants. When prioritizing work, their removal should rank far lower than the priority to extend the areas cleared of Ivy and Blackberries.