Garden Talk: Weed IDs

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• Expert: Know Your Weeds For Successful Control

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  Weeds, ultimately, are in the eye of the beholder, according to a Wisconsin horticulture expert.

  Barb Larson, horticulture educator for University of Wisconsin Extension in Kenosha County, said that what is a weed to one person might be a desirable plant to another. A plant placed intentionally can attain weed status if it is too prolific and takes over the garden.

  Weeds are often the hardiest plants around, and Larson said that this year seems to be an especially good one for them. She surmised that it might be the combination of plenty of rain and moderate temperatures that has them really prolific.

  “Everything’s just really taken off,” she said.

  Weeds are also opportunistic, Larson said.

  “There have been some plants that didn’t make it through the winter, so some of the others are kind of filling in. Sometimes, it’s something they planted and sometimes it’s something they didn’t that’s showing up,” she said.

  Figuring out which weed one is dealing with is an important first step in knowing what approach will be best. Larson said her first step is to figure out if it is an annual, or a perennial.

  “Something that’s coming back from the root system,” she said.

  Larson said that to manage or control many weeds, regular handpicking is often the best option. Especially for annual weeds, or biennials that can be caught before they go to seed, it’s a no-cost, chemical-free approach. Hoeing and mulching are other options for those varieties.

  Even for some perennials, Larson said, handpicking can be used to control weeds, although it may take more vigilance. The payoff is being able to limit chemical use in the garden.

  “But if it’s pretty pervasive, or a real problem,” Larson said, “I could try everything from trying to cover it up with plastic, cardboard or something like that … to exclude the light from the plants and hope to kill them that way.”

  For those not opposed to using chemicals, Larson said that there are herbicides available.

  To know whether a weed is likely to cause problems, and to determine which herbicide will be effective, identification is key.

  Mark Renz, a UW Extension weed specialist, has created an interactive database that gardeners can use to correctly identify a weed. It walks the user through a series of questions to narrow down the possibilities.

  But Larson warned that it is better to add in fewer criteria than more to make sure that the right species is not eliminated accidentally.

  “Pick just a few of the characteristics, and the ones you know for sure. And then you’ll get a series of photos and you can identify it from there,” she added.

  A combination of wildflower and weed identification books can also be useful, according to Larson.

  When bringing a sample in to the county UW Extension office for identification, Larson said it’s best to “bring in 4 (inches to) 6 inches so we have stem and the leaves, so we know the leaf pattern on it. And ideally, you also bring it in when it’s in flower.”

  She went on to explain that traditionally, plants were categorized by the flowers and the flower structure, so seeing it in bloom can go a long way toward a correct identification.

  If a person can’t beat them, sometimes they can eat them instead.

  A listener to “The Larry Meiller Show” who identified herself as Lisa asked what to do with purslane, which is taking over her garden.

  “Eat it!” said Larson. “It’s edible, although I have tried it, and it’s a little too ‘green’ tasting for me.”

  Larson said that if that option doesn’t appeal to Lisa, that purslane spreads by seeds, so a thick layer of mulch will help control the spread.