Roses may be red, but violets aren't blue

"'Roses are red, violets are blue...." Hmm, well, so much for the accuracy of children's doggerel. Some roses are red – that's true enough – but they have an amazing number of other colors, too. As for violets, if there is one that is a real "blue" – I mean a true ultramarine or an authentic cobalt blue, the sort of blue blue seen in the sky – then I'd like very much to meet it.

Violets aren't "blue." At least not here in Glasgow, Scotland. It's true that you do get pink ones, and yellows, whites, and all kinds of in-between colors, but the archetypal color of a violet, as its name suggests, is violet. Like oranges are orange.

There are dissenters to my view. One writes: "I have heard – but am not sure if it's true – there's a "real blue" one that's native to the US, maybe to the Midwest." Well, anything may be true in the Midwest. But I'd like proof.

There are other popular ideas about this small, traditional, and delightful wildflower that are a tad more accurate – as when someone is described as a "shrinking violet." Violets are indeed rather shy (even if they can also spread like wildfire in places that suit them).

What I mean by "shy" is that they aren't six feet high, take-notice-of-me plants. They like to hide themselves in grass or lurk in hidden corners. Their flowers are not loudly declamatory on long stalks, but rather self-effacing and definitely little.

They don't much like to be brought out into the open. I picked a violet flowering in the garden the other day to bring it indoors because I wanted to look at it closely. I gave it good water to drink. But it chose not to. What it did was shrink. The flower turned to crumpled paper in the miniature vase and is now brown and sinking.

Wildflowers don't always take kindly to domestic arrangements, reminding humans that plucking flowers for our own pleasure is not necessarily as natural as we like to think. I was, after all, interfering with the violet's natural intentions – to turn from flower to seed and seed to future generations. In the big outdoors, it would have fulfilled itself just fine.

As a matter of fact, the patch of ground around our house is, as the years trot along, proving itself distinctly violet-friendly and violet-productive. Earlier in the spring, I thought 2006 was not going to be a good year for them. I was wrong. They have, perhaps a bit late, cropped up in all kinds of unsuspected places and flowered with (for violets) happy abandon.

I am particularly proud of one kind of violet that shows up in crevices and cracks between our paving stones and is even thriving under the shadow of a cotoneaster. This type has a slightly larger and more strongly hued flower than the commonest kind we have, which is what the Scots would call "peely-wally" – faded and pale.

"Violet" can be a surprisingly vivid hue, and yet still be different from "purple." This deeper, richer kind of violet flower is the one I'd like to cultivate even more ... though cultivation doesn't really suit wild violets.

I have no idea how this deeper violet happens to be in our garden. It certainly wasn't here when we arrived 25 years ago. It doesn't grow wild around here. Nor did I steal a plant of it from another gardener – though I was gravely tempted to do just that when I saw a veritable diaspora of them flourishing haphazardly in John Brookes's garden.

Brookes is one of Britain's notable garden designers. His violets put mine in the shade. Yet "his" and "mine" are not really apt words. You may welcome violets, you may encourage – or at least do your best not to discourage – their presence, but you can't possess them. If they choose to stay around you, fine; if not, too bad.

In Brookes's garden, it is his advocacy of gravel that most pleases the violets. He uses a lot of gravel. They love to seed in it at will. And my own keenness on gravel, stimulated by Brookes's liking for it, has had a similar effect.

Yet, in Brookes's "Book of Garden Design," I have found no mention of violets. Perhaps this is because they do not add their small punctuation marks to a garden by design. You can't design violets.

In a manicured, mowed, and admirably weeded garden, the violets are likely to vanish. The pleasure of having them is a good argument for not too much zeal and rigor in one's gardening habits. It is also useful to be able to recognize their heart-shaped leaves when they are not in flower, to avoid yanking the plants out.

I should here admit something. Although I have insisted that violets are violet, we do also have some of the other colors. I have deliberately planted them, but then I have left them to their own wild devices.

Year by year I never know where – or if – they will reappear. Violets need to be secretive. They have to be looked out for. It's part of their charm.