Q. Mike: I have very little area in which to garden. One plant I find to be trainable and easy to grow is the morning glory. I help the vines find their way onto fences out back and electrical poles out front. Some of my neighbors love them; others call them a "noxious weed". If my vines aren't growing over other living plants, are they 'weeds'? Is the term "weed" purely objective, or is there a subjective view of what is and is not a weed? And should my neighbors be afraid? Am I helping to propagate something terrible; or am I growing a beautiful flowering vine that softens the view of concrete and asphalt? Thanks for your input,
- ---Bruce in Center City Philadelphia
Let's take running bamboo as an example. It's a beautiful four season plant that produces incredibly useful wood, provides cover for wildlife and can be used to make great trellises, bean poles, arbors and other garden supports. (It's also the strain of bamboo that's the source of the edible treat known as bamboo shoots!) But its 'running' habit can overwhelm natural areas, lawns, gardens and even structures. In a dedicated area where it is restrained on all sides, it is a sensational plant. When placed where it can grow unchecked into wild areas or the property of others, it is the most noxious of weeds.
(Note: If you love the look of bamboo but don't want to risk becoming a horticultural terrorist, check out the many varieties of clumping bamboo—equally beautiful, but eminently more well-behaved.)
Perhaps the most currently vilified 'weed' is garlic mustard. It secretes compounds that kill surrounding plants—including big honkin' trees. It threatens a native butterfly by looking like its host plant, but is instead toxic. And deer won't eat it, so they devour native plants while this monster spreads unchecked. But it is edible by us humans, with flavors of garlic, mustard and horseradish; it may have great potential as a medicinal plant; and it is reportedly not a problem in Europe or other areas where it's considered Native. Weed here; useful plant there.
I personally grow a lot of plants that others call weeds. My family loves the sweet, flavorful, raspberry-like fruits of the escaped ornamental known as 'wineberry', and so I protect every brilliantly red cane that appears on our property. I anxiously await the thousands of sulfur-colored flowers that bloom up and down the dramatically tall spikes of mullein—bees and other beneficial insects love the small flowers as well—and always leave a few plants in place, even when they pop up in my raised beds. And wild violets are simply pretty plants whose edible flowers provide the otherwise hard-to-find nutrient rutin in its most natural form.
But all three of those plants drive others to herbicide and bad language.
And so, any morning glories that adorn your personal property are beautiful annual flowers that make great use of limited space by growing their vines faithfully up any support you provide. They even reduce summertime cooling costs when they're trailed up a sunny wall, diverting a ton of heat without doing the structural damage that self-clinging vines like ivy can cause.
But any vines that escape to sprout up on the property of others are weeds to them. Morning glory vines that are not supported by strings, trellis or fencing flop around in an ugly tangle—or climb all over the plants your neighbors had HOPED to see. And if they successfully re-seed themselves, they can be a bear to eradicate.
In really warm climes, the morning glories that are annual plants here in the North become perennial, and can easily be considered noxious if not controlled. And even though true morning glories are annuals—that is, plants that die over winter and technically must be started anew every year—they can drop a lot of seed. Some winters—maybe most—those seeds won't survive in areas with freezing temps. But when they DO, the number of vines that explode out of the ground in the Spring can be Biblical. It only happened to me once, but it took all summer to get the things under control, and I never planted morning glories again.
Your location favors seed survival because of the heat sink the city creates. And Center City Philly is an ancient neighborhood—it contains the two oldest continuously occupied blocks of row homes in the nation—and the houses tend to be jammed together, making it easy for a plant to get communal.
So stop growing them up power poles, where they can easily travel to drop their seed where it isn't wanted (and maybe even make mischief with the odd transformer). Keep them close to home; don't grow your vines up into areas that will allow them to wander off your property. If a vine starts to get frisky and tries to make a hard right into someone else's backyard, pull it down ASAP.
And if you notice the vines returning some Spring without you having had to plant fresh seed, be vigilant! Look for stragglers outside your property, take personal responsibility for them, and pull them up or spray them with white vinegar or other non-chemical herbicide on a dry day. Because at your house they're probably among the best flowers you can grow. Next door, they're weeds.
Oh and one final note: There are white varieties of cultivated morning glory that are as annual in nature as their more familiar blue and purple flowered cousins. But if you didn't PLANT white morning glories and white flowers appear on morning glory-like vines, destroy every last one: That's bindweed, a noxious perennial that loves to strangle other plants. Here's a link to our previous Question of the Week on that persnickety plant.