I love the berries at Christmas on an old English Holly at my place. Robins swarm in a month later and devour every berry. Then they perch in a nearby Doug Fir and poop out seeds. I'm always weeding holly babies under the fir. I wouldn't cut down the old tree though. Down the road at a Doug Fir Farm there's yellow berried English Holly popping up in abundance. There very beautiful. I don't think they're competing with the firs.
Maybe it's a good thing that vagrants are hanging out under the holly trees. They're probably trampling all the babies.

bboy,

Some of the plants on your list I wouldn't grow because they are either disease prone, short lived, or there is a native which could fill its place. I like the many different types of the English Holly but I hate dealing with the prickly leaves, so enjoy them from afar and at Xmas for decorations. My favorite holly is Ilex latifolia, the large leaved holly, which looks almost like a evergreen magnolia. It also doesn't have the thorny leaves. But I imagine that if they ever get as popular as the English Holly, they would become a problem also. I also enjoy the two evergreen cherries, not as trimmed hedges, the English laurel and the Portugal laurel and would hate to see them eliminated from our landscape. I also enjoy eating sweet cherries, but that cherry is a far bigger problem than either of its two evergreen cousins. Last weekend the escaped sweet cherry was in full bloom. Driving up highway 18 through Maple Valley and toward Tiger Mountain, they were really noticeable in the woods. As thick as Scotch broom along a freeway road bank. I have never seen either of the evergreen cherries come anywhere near that population density. So yes, if there is going to be a list of plants not to plant, the sweet cherry needs to be on it!

That is the trouble with non-native plants from similiar habitats and climates as ours. They like it here, our native wildlife have taken a liking to them, so they will reproduce and probably can become a problem. Or are they a problem. It depends on where you are coming from. I like wildlife so to me any plant that provides food and cover for them is not a problem. Even our state wildlife agency maintains apple and cherry orchards on their managed lands for wildlife.

Speaking of apples, the only non-native plant I have seen while hiking in the Olympics has been the common apple. Probably started there by a thoughtless hiker who discarded an apple core, thinking it was bio-degradable. Not thinking it was a perfect packet for germinating a apple seed. Of course the deer and bear enjoyed the fruit, as well as any hiker who came along when the fruit was ripe. Maybe apples should be on that list.

You may be interested in this publication. Frequency of each of 1,358 species of both native and non-native plants seen growing wild here is indicated.

"Purplish-black cherry-like fruit ripens in the late summer or fall; birds eat these and deposit the pits everywhere. Shade tolerant, ENGLISH LAUREL is weedy in our wooded parks, where some specimens are more than 40' tall, wider still"

"Portugal Laurel...thrives in our climate, and comes up wild, especially in woods, just like its more familiar cousin ENGLISH LAUREL"

Where either of these are planted in neighborhoods here hundreds come up in garden beds as well as on nearby uncleared wooded property. Sections of some city parks are now nearly filled with an artificial spontaneous vegetation consisting of laurel, holly, ivy and others on my list.

Here is a link that might be useful: Wild Plants of Greater Seattle

This is a timely thread! I was recently at Luther Burbank park on Mercer Island, and noticed failry large Stranvaesia's growing in the woods. I thought they probably were planted there on purpose years ago, but wondered if they might have volunteered by the woodsy places they were growing. Thanks for the information Ron.

I think that's the same park I've seen a wild patch of Viburnum lantana, near the water. The stranvaesia pops up here and there all over, it seems, as do certain cotoneasters.

I am not surprised that Seattle has so many naturalized English and Portugal laurel. There are so many in the landscaping in that area. My neighbor has a mature Portugal laurel in his yard and in the ten years I have live here I can count on one hand the number of seedlings I have had to pull. There are even more English laurels around my neighborhood and I rarely get a seedling in my garden.
I do fight English ivy all the time. Every spring I get hundreds of them sprouting throughout my garden.
Another plant that I get lots of un-wanted seedling are various species of Cotoneasters. I see them in the woods very often, and in the fall and winter, the evergreen ones really stick out. Maybe they should be on your list.
The other day I noticed naturalized lilacs growing in the ditch along state route 900, between Issaquah and Renton. I have seen them naturalized in the Blue Mountains around and between Walla Walla and Dayton. I have also seen them growing wild around Belfair and Shelton. Another plant for the list?
I have heard, but not seen, that some species of barberry are starting to become a problem.
A plant that I thought would not be a problem is the Hydrangea. I have seen it in the woods north of Aberdeen and growing among the native plants around Lake Quinault. Another possible plant for the "do not grow" list.

Before you know it, there wouldn't be a plant found at a nursery worth growing. Even the common carrot has naturalized in Washington.

Portugal laurel seems to be reseeding more than it used to, perhaps influenced by climate change. Some planted at my friend's Camano Island place are now generating hundreds of seedlings in the beds - although in this particular instance increased irrigation may be having an effect.

Common lilacs wouldn't be expected to reseed much, if at all. In fact, Jacobson (above) doesn't list any lilac species as growing wild in Seattle. Like roses these do often persist after homesites have been abandoned.

My list is of some that have demonstrated a serious pest presence already. There are certainly others that could be added, such as butterfly bush. Occasional occurrences of other ornamentals away from obvious current cultivation does not always constitute growing wild, nor does a lack of an obvious problem right under one's nose indicate that it isn't happening big time elsewhere nearby - or that noticing and responding to problem plants is silly.

I don't know about the WA side but the OR side of the Columbia River Gorge is full of ivy and laurel. A lot of it is on old home sites. I have seen roses on old sites too.

Portland's Forest Park, Washington Park and other forested areas around town are smothered in ivy too. It is horrible.

I don't even know where the holly is in my neighborhood but I pull up dozens of seedlings annually and they are tough buggers to pull out even when tiny.

English holly is an increasingly big problem in the Portland metro area, in fact it is one of the first to colonize otherwise intact natural areas. It can create a total light blocking understory as it grows into large tree form thickets. Wide bird dispersal, able to withstand extreme shade, forms extreme shade underneath itself, becomes a good sized tree; all make for a very big problem.

Norway maple is a serious pest in parts of eastern Washington... notably Pullman.

I've seen Stranvaesia turn up in some of the oddest places. I thought I saw one along Highway 101 near Gardiner recently.

Sasa palmata sure creates a mess wherever it gets going... let's hope it never goes to seed or it may just take over the whole Northwest. I've seen it running wild in a few different places.

Buddleja used to be all over the place along the lower Dosewallips river... I haven't checked lately though.

I am confused about Norway Maple -- is this the big leafed Maple we called "Manitoba Maple" or a "soft" maple? Its sort of a weedy suckery tree, definitely not a syrup maple, very large with a large canopy. As the articles say, nothing grows under it, except that nasty daphne which is an obnoxious plant too.

Norway maple is Acer platanoides. It normally produces leaves 4"-7" wide, occasionally up to more than 10" wide. Manitoba maple is a common name for A. negundo. The common name soft maple has been used for A. saccharinum.

Oh dear. I planted quite a few of those. I can attest after 2 years 4+ months that periwinkle, while beautiful and robust, is taking over. It will take hours, maybe days, to get it out of the heathers, azaleas and other plants it is smothering. It is confined to raised cottage stone beds, fortunately, although it is spilling over the walls and rooting below. I don't think it will be able to compete with the miniature ivies and fleur de lawn and trees but we'll see. We bought the colors that match our wildly painted house so it's blooming now and looks really good!

Just planted a sweet cherry, Prunus avium 'Lapins' -- cherry trees are said to be THE favorite bird attracting tree. Asked about it here first :-)

English laurel hasn't been easy to get established in this yard. Neighbor planted 16 of them along our east fence and most of them died too, although there's enough left to someday provide some privacy if they're left alone.

I planted 3; 1 has survived. Also 1 out of 2 'dwarf' survived. The dwarf is growing more than most 'regular' plants.

Have 2 Nellie R Stevens hollies. They were touch and go but seem to be doing very well now. Very pretty trees. Want a lot of water. Planted a little blue boy holly to help pollinate all the hollies. Very happy bees, lots of varieties of bees. We have robins but they haven't been interested in the holly berries. They are riveted on the earthworms.

All my neighbors are anti-nature, anti-plant, anti-trees -- doubt anything will ever sprout and survive in the immediate neighborhood. Birds will have to carry seeds far -- this whole area is becoming urban and ultra-over-developed very fast.

Neither of those are English holly (Ilex aquifolium) cultivars.