Sunday, February 24

Know your enemy

The five most noxious weeds

When I moved into my home, I inherited more than the house. I inherited the weeds. One weed, in particular, has vexed me relentlessly. Between the gravel drive and our home, lies a patch of rocky dirt in which someone lovingly planted Bouncing Bet (Saponaria officinalis). Bouncing Bet, it turns out, is a notoriously tenacious weed. It spreads by underground stems and has managed to lodge itself into my home's foundation. For seven years now, I have dug it up, poisoned it, and even planted other invasives in an attempt to upstage it. I may not have eradicated it yet, but I know each year I weaken it. Plant biology 101 assured me that plants must photosynthesize for energy, and so I am slowly starving it. Someday, I will probably miss seeing that familiar foliage pop up along the driveway.

Do you have a personal relationship with your weeds? Do you know what they are, where they grow, what makes them tick? The old saying goes, "Keep your friends close and your enemies closer." The same applies to flowers and weeds. You wait and watch for your beloved Baptisia to bloom and fail to notice the thistle setting seed beside it. Weeds are smart. We have to be smarter. Gardeners need to develop game plans, much like coaches. Coaches study the competition and create offensive and defensive moves to exacerbate their weaknesses. The process starts by studying the competitors.

Although our society has formulated a formidable arsenal of chemical weapons to be used against these garden villains, I won't go into much detail on them. Our environment has enough problems without gardeners adding to them unnecessarily. Two chemicals I would recommend having on hand include corn gluten meal (a naturally derived pre-emergent herbicide) and the ever popular Round-Up. Corn gluten meal poses no danger to animals or people. It will prevent your weed seeds from germinating, but it will prevent flower and vegetable seeds from growing as well, so time your application appropriately. Round-Up is a last ditch response to be used when all other efforts have failed. Because it is a systemic herbicide, it is invaluable on weeds with extensive root systems. Because it is a respecter of no plant, apply it carefully, or you'll be eliminating more than your competition.

1. Thistle.
Thistle is the daddy of the bad boy weeds. Armed with thorny leaves and stems, this plant is the number one reason to weed with a pair of leather gloves handy. Annual and biennial thistles reproduce by seed only, but perennial thistle represents a bigger challenge. In both cases, you must not let thistle go to seed. Write this 25 times on a piece of paper before spring arrives. Continually removing the top of the plant and preventing seed set will eventually weaken perennial thistle. (But prepare to be a little weakened yourself.)


2. Dandelion.
As a mother of three young children, I cannot deny the beauty of a bouquet of freshly picked dandelions. As a gardener, it delights me doubly, because in that pudgy little grip lies a handful of invasive weeds that will never set seed. Dandelions can reproduce by seed and by root pieces. When you dig dandelions, be sure to dig deep and get every bit of the taproot that you can, or else you'll be seeing it again. Take my advice, invite several small children over to pick all the lovely yellow flowers, and you'll have a wonderful time twice over.


3. Bindweed.
This weed bears ridiculously long roots. As a laborer on the perennial farm, I used to compete with my fellow workers to see who could pull out the longest bindweed root. I assure you, none of us ever pulled an entire root out, but we certainly had some with lengths of 20 inches and up. For this reason, you may need to resort to Round-Up on a bindweed infiltration. Keep in mind that you can weaken the plant by continually removing the foliage and stems, so start there first. Bindweed reproduces by seed and by root pieces. Note: Morning glory is a cousin to bindweed. Although I find the blossoms enchanting, I never plant morning glory because the risk of introducing that invasive root system gives me nightmares.


4. Crabgrass.
Familiar to all, this ratty looking grass reproduces by stolons (above ground stems) and seed. Pull crabgrass out before it can set seed. Consider waiting to apply nitrogen to your plantings until the fall, when it will not be quite such a feast to crabgrass. Applying mulch to your borders will prevent the seeds from finding a sunny spot of bare soil on which to germinate.


5. Creeping Charlie.
Also known as ground ivy, creeping Charlie can be a real challenge to remove once it has a colony established. It spreads by seed, stolons, and root pieces. Some Midwestern universities have recommended treating with a dilute Borax solution (10 ounces of Borax to two and a half gallons of water over 1000 square feet), but this is potentially hazardous. The possibility of actually burning your lawn or beds is very real, as is having to replace your soil if you apply it too heavily. Ground ivy looks like tiny geranium or mallow leaves, but is actually a relative of the mint family. The square stems and minty scent will confirm its identity. Since creeping Charlie grows better in the shade, consider selective pruning to introduce more sunlight to the affected area.


Three more to know:
Prostrate knotweed is sometimes mistaken for grass or crabgrass. But as it grows, its long branching gives away its identity. The stems extend a foot or more. Knotweed is an indicator of compacted soil. If knotweed is growing in your beds, it's time to aerate or loosen the soil. It thrives in cracks in my sidewalk, and along my gravel drive.


Purslane bears thicker leaves, like the sedum family. It reproduces by seeds and stem fragments. I generally just pluck it out of the ground, but if the whole plant is not removed, it will be back again.


Common mallow is sometimes confused with creeping Charlie. Mallow has larger leaves and doesn't spread by stolons. It grows a taproot and spreads by seed alone. Preventing seed set will weaken the colony.

Mollie Uftring developed a green thumb as a teenager working in the perennial beds at Hornbaker Gardens in Princeton, Illinois. After graduating from the University of Illinois with a degree in ornamental horticulture, she worked as a landscape designer in Ohio before returning to Illinois.