Blue Flowers with Bad Habits

Credit: Greg Vaughan

From my earliest days in the garden, I have loved blue flowers. As a fledgling gardener, this inclination sometimes got me into trouble, especially before I learned to read catalogue descriptions with a rational mind. Nowhere were my growing pains more acute than in the perennial border.

Remembering blue cornflowers and red poppies growing wild in the fields and meadows of a European childhood, I seeded annual cornflowers throughout my first gardens.

Thrilled to discover that a perennial blue cornflower exists, I ordered seeds of Centaurea montana with the enthusiasm of the novice. At first, I was delighted by the vigorous silver-green plant with its long season of beautiful blue bloom. It was the beginning of my first perennial border.

Unfortunately, Centaurea montana soon became the entire border. It took several years for me to learn ruthlessness, and a few more to discover that scrupulous deadheading is essential with this plant, which spreads easily by self-seeding as well as by its roots. I now forcibly restrict it to a small group of plants in the middle of a large mixed border. Its foliage springs up in plenty of time to hide fading narcissus leaves, and its undeniably beautiful flower colour is an asset for a long period. It blooms with the dianthus and the iris, providing, respectively, pleasing combinations of contrast in colour and shape.

A packet of Veronica spicata seed was another part of my early acquaintance with growing perennials, and the plants quickly became favourites. It was thrilling to discover what a large genus is Veronica, and my next discovery was the wonderful blue of Veronica teucrium. This plant is not invasive in the least, but keeping it attractive requires considerable maintenance. It is floppy. Its centre seems to disappear, leaving unsightly gaps surrounded by a ring of bloom that only accentuates the bare middle. It requires staking, but man-made contrivances spoil its informal shape. Carefully chosen, lightweight branches will support it successfully, though it is a fiddly business getting the right size and shape to avoid an unsightly twig network. Ideally, I dig and divide my Veronica teucrium every year. If I let it go a second year, it’s still okay. But if I leave it for a third year, it is disastrously (if colourfully) messy. It should not be the choice of someone looking for a low-maintenance plant.

Even more invasive than perennial cornflower is the common but lovely forget-me-not, Myosotis alpestris. Great sweeps of them float through my garden spaces in spring, highlighting the reds, pinks and yellows with their gentle, washed-blue billows. Early in June, however, they transform into an army of unsightly seed-heads, and the plants must be pulled up wholesale. Of course, I cannot resist composting such a large supply of organic debris, thereby guaranteeing that I will have a plague of additional forget-me-not seedlings. Summer and fall maintenance includes the liberal destruction of volunteer forget-me-nots, as well as considerable transplanting to arrange them somewhat. They certainly add a great deal of work to my schedule.

Any blue-loving gardener collects the many delightful species and cultivars of Campanula. Some years ago, I accepted a plant of Campanula rapunculoides (rampion) from a friend. “Oh, it’s such a lovely blue flower, just the sort of thing you like, and it requires no care at all.” She was absolutely right. With no care, in fact with violent abuse, this scourge of the perennial border spreads, blossoms and spreads some more. Its roots are thick, fleshy and brittle, and the tiniest sliver remaining behind will grow vigorously into a clump when your back is turned. It is positively dreadful, and while it may be pretty, there are other plants that fill the same colour and shape requirements with far more civility. (Adenophora has a similar flower and is perfectly well behaved, as its common name, ladybells, suggests.)

Finally, there is the undeniable conqueror of the blue-loving gardener, the evergreen periwinkle. Vinca major is the taller, sub-shrub form, with flowers on longer stems than Vinca minor, the ground-hugging type. The foliage of both is a shiny deep green year-round. The single blue flowers are charming and generous for most of the growing season. Many of us place this plant in a spot “temporarily,” to fill up the space until other things grow up, but if those other things are rhododendrons, their future is in jeopardy. The periwinkle’s dense root structure will eventually choke out anything less doughty than a full-scale tree. When the time comes to uproot the periwinkle, it is an almost impossible task to extricate all the roots.

This is not to say that the attractive periwinkle doesn’t have its place. I have learned to plant it where I won’t grow anything else. In a wild area along a creek on my property, periwinkle covers the ground under tough native shrubs and trees; it prevents the bank from slipping into the creek and prohibits weeds from settling there.

In spring, the currant and salmonberry blooms announce the first hummingbirds, and the lovely sheen of vinca foliage is a delight even for the short months that the blue flowers don’t gladden the eye of this incorrigibly blue-loving gardener.