Happy to report that I'm not the only garden person that allows a plant to get out of control because something interesting might occur (which sometimes happens and sometimes does not). Washington Post columnist Barbara Damrosch did just that this summer with nasturiums and it was a little bit of both (which sometimes happens and sometimes does not):
Nasturtiums on the Loose
By Barbara Damrosch
Thursday, October 14, 2010;
It was a great beginning. The row of Alaska nasturtiums I'd planted made a tidy border along the outside of our home greenhouse, the "compact, mound-shaped plants," as the catalogue described them, perfectly filling the foot-wide bed. Alaska is a variety with large flowers in great shades of butter yellow, orange, red and mahogany, on long pickable stems. Even the foliage is pretty, spattered with white markings. And they're edible: the flowers, the peppery leaves and even the round seed pods that you can pickle as a substitute for capers.
As summer wore on we took to leaving the greenhouse door open every day to ventilate the crop of trellised tomatoes inside, and a strange thing happened. The nasturtiums started to creep over the door sill and make themselves at home inside. "Let's leave them," I said to my husband. "They're cute."
A week or two later, they figured out how to slither under the greenhouse's steel base and began to invade all along the front. Soon they were heading down the paths between the tomato rows. "It's charming," I insisted. "They're like a colorful mulch. It looks like Giverny in here."
They have now climbed three or four feet up some of the tomato vines, rollicking in the greenhouse's tropical warmth. Outdoors, some of the seeds have scattered about the yard, and they are capering in places they were never planted.
Comparing a number of catalogues, I see that Alaska is sometimes described as compact, sometimes as trailing or climbing. Perhaps there are different strains. But I also wonder if they grow differently in the fertile, richly organic soil I give my vegetables. That's certainly what happened with Lemon Gem, the little citrusy-flavored marigold I tried in my outdoor vegetable plot, for its "8- to 10-inch neat, low mounds." Mine grew almost to my knees, then flopped over, obliterating the garden's central walkway.
Mixing flowers with edibles can make a vegetable garden look beautiful, but sometimes it just doesn't work. A food gardener's strategy is to pump out food, as much of it as possible. Plant spacing is carefully thought out. Tomatoes need a good root run and space around them to let in sun to ripen their fruit. A carrot needs four square inches of the earth to fulfill its potential. Monitoring these principal players is hard enough, what with wandering squash vines and roving pole beans, without some out-of-control flower over-decorating the scenery.
I have a Clematis tangutica vine that smothers at least one edible crop each summer, hanging over the wrong side of the veggie fence with lovely yellow bells that would make Gertrude Jekyll swoon. This time it ate the beets, and it must die. Maybe next year.
Damrosch is a freelance writer and the author of "The Garden Primer."