Rereading Margery Fish, a garden writer most active in the 1960s, I was struck how plants can behave differently from one garden to the next. Plants she describes as invasive are not so here, and some I finds invasive she does not. As she puts it: "one can only speak from one's own experience in the gardens one knows". Lysimachia Clethroides, with its shepherd's crook white flowers, was a menace in our previous garden, but M. Fish finds it does not spread much.
|Lysimachia Clethroides and Morning Glory|
Margery Fish rarely describes plants as invasive. She talks about them as she would of friends. They might have their faults, but invasive is probably too rude an epithet to use. Instead of being invasive a plant is "far too friendly", "has a seeding habit a little trying", "I would love (it) more if it didn't wander so far afield", "somewhat too obliging with their thrusting white roots", have a "habit of popping up in the most unexpected places" and, as she would say of an acquaintance she did not particularly like: "I should not miss it very much if it walked out one day" (it has been my experience though that it is always the wrong plants that walk out on you!).
Some plants are invasive in just about every garden. Only with tireless efforts are you going to get rid of the attractive Campanula rapunculoides, described by Reginald Farrer as the "most insatiable and irrepressible of beautiful weeds". According to Margery Fish, the only way to get rid of it is to dig up the soil where it grows and burn that soil!
However, still in the campanula species, she describes C. alliariifolia as providing "an occasional seedling". I also grow it, and I like its "long spires of hanging cream bells which get smaller as they climb". However at Roche Fleurie there is no occasional seedling, but dozens and dozens that need to be pulled out each spring, and this, many years after I got rid of the mother plants.
|Campanula alliariifolia is the white bellflower in the middle - I don't have any good pictures of it. As is usual with plants I finds invasive. I take for granted I have numerous pictures of them and I don't.|
Some plants might be invasive generally, but not in your garden because of specific conditions. For instance, I can see that Rose of Sharon, Hypericum calycinum, runs wild in most situations. However, we grow it in a very tight spot between a low stone wall and the paved path where there is great difficulty for it to expand. Besides, Rose of Sharon is border-line hardy for our area, which must contribute to keep it in check.
|Rose of Sharon|
Sometimes, a plant simply does not like your garden even when that same plant is weedy in most places. This is the case for us of Corydalis lutea. It self seeds with abandon in the gardens of most of our neighbours, but does not survive for long in ours. It is also the case of Kenilworth Ivy (Cymbalaria muralis) which manages to survive here, but not vigorously.
Even what is invasive can change with time. My friend Gwen had to lead a constant battle against Honesty (Lunaria) and Johny Jump Ups (Viola tricolor). Both plants have now more or less disappeared from her garden!
I am sure all of you have plants that are, as Margery would have put it, "far too friendly" but are rather shy in other gardens (and vice versa).