Unless we garden in very small areas, we all have "wild" parts of the garden where we expect plants to be able to take care of themselves and compete with the local vegetation. Plants that can be relied on to do so will be different for each of us, depending on local conditions. I have tried in this post to list some of the ones that can put up with our poor alkaline soil, which tends to be on the dry side in summer and is always wet (when not flooded) in winter.
One of the most interesting of these is the Grecian Foxglove, Digitalis lanata.
This foxglove could be described as independent minded. It usually decides where and how it will grow. I have often collected seeds and planted them where I wanted the plants to grow, but to no avail. Every year, several of them turn up. but not where I have planted them. They can be moved, however. They more often grow singly, outside the boundaries of the garden proper, on grassy banks where they get a fair bit of sun. Last year, one appeared right in the middle of a clump of Narcissus poeticus. Digitalis lanata is described as a perennial for shade. However, at Roche Fleurie, it grows mostly in sunny spots and is biennial.
|Digitalis lutea and D. grandiflora|
Two other digitalis species that can fend for themselves are Digitalis grandiflora and Digitalis lutea. These are actually perennials and tend to grow in clumps. They are not as independant minded as Digitalis lanata. They will usually grow where you plant them. In the picture above, lutea is the one with very small flowers, whereas grandiflora is the one with larger flowers. Having them grow side by side, you can see where grandiflora gets its name, even if, in fact, the flower is not big. Lutea is the more prolific of the two. The ones above have been surviving on their own for at least 10 years among the cinquefoil (Potentilla recta), cow vetch (Vicia cracca) and buttercups (Ranunculus repens).
|Sweet Williams growing in the grass|
One plant which, to my surprise, is able to naturalize in the grass is Sweet Williams, Dianthus barbatus. I do not remember ever planting it outside the garden wall, but it has come up through the grass and seems to be doing well. It is not as lush as when grown in a garden with no competition. In the grass, each clump includes fewer flowers, sometime only one or two. However they acquire a unsophisticated charm that the large pampered flower heads of the garden-grown plants do not have.
Other dianthus plants also colonize dry sunny areas around the garden. Pinks of mixed origins, like the one above, appear in the gravel of the driveway in full sun.
In mowed areas over the septic field, many clumps of Maiden pink (Dianthus deltoides) elbow out their way through the short grass. In fact, in that sunny, sandy area, the grass seems to finds it harder to survive than the Maiden pinks which do not mind being dry after it has bloomed.
As our soil is alkaline, the red valerian, Centranthus ruber, does naturalize. However it does not share my opinion about where it will be happy. There is a sunny area below a low dry stone wall where it should prosper, but it only sprouts in parts of the garden where it is not wanted. That is the nature of volunteering plants.
Colchicum does not seed itself and so you cannot say that it has naturalized here, but if you plant the bulbs in grassy areas outside the garden, they will survive quite well, the clumps getting larger each year. I find outside the garden is the best place to grow it as you tend not to notice the large leaves in the summer, even when they are turning brown, and the plants bloom just as well as they would with no competition. This is true for many bulbs, including Anemone blanda and of course narcissus.
|Yellow Loosestrife and peach-leaved bellflower|
I could mention more naturalizers. I will close with this grouping of Lysimachia punctata and Campanula persicifolia, which are both able to grow through grass. If it is wet, yellow loosestrife can actually become rather pushy as the clump shown below on the bank of a brook at the Métis Garden.
|Yellow loosestrife naturalized|