Weeds Watch: A Month-by-Month Calendar
Here are weeds to watch for in your landscape each month.
How to Control Hairy Galinsoga
Although its name might not be commonly known, hairy galinsoga is one of the world’s most widespread weeds.
Odds are good you’ve had it in your own flower beds and vegetable gardens no matter where you live in the U.S.
This weed is most noticeable in early to mid-summer when it’s producing quarter-inch, button-like little flowers of four to five white-petaled rays around a central yellow disk.
The flowers look a bit like miniature daisies, which gives rise to one of hairy galinsoga’s nicknames – “Peruvian daisy.” It’s also sometimes called “quickweed” and “shaggy soldier.”
Native to central Mexico, hairy galinsoga is a prolific seeder that’s especially common in the eastern and mid-western U.S. It’s also found throughout much of the world.
Although hairy galinsoga is an edible member of the aster family, it’s seldom used for that purpose. Most gardeners attempt to eradicate it when it tries to grow in a vegetable patch.
Hairy galinsoga. iNaturalist
Getting to know hairy galinsoga
Hairy galinsoga (Galinsoga quadriradiata, a.k.a. G. ciliata) is a summer annual that germinates during two or more months from early spring to mid-summer, peaking from late May into July in most of the U.S.
Plants are variable in height, ranging from six inches to about two feet tall with multiple branches up the stem.
The leaves are egg-shaped, light green in color, toothed around the edges, and pointed at the tip.
A tell-tale identifier (and reason behind the weed’s name) is that the stems, leaf edges, and leaf upper surfaces are covered with small, dense hairs.
The flowers appear for weeks in early to mid-summer, maturing to produce as many as 7,500 seeds per plant. Plants then die at season’s end.
Hairy galinsoga is a versatile plant that can pop up in a variety of conditions, including full sun to part shade and moist or dry soil. It particularly thrives in disturbed soil, where the loosened surface aids germination of the plant’s numerous seeds.
Young hairy galinsoga plant. iNaturalist
Solving a hairy galinsoga problem
A saving grace of annual weeds such as hairy galinsoga is that they aren’t well rooted and are easy to pull or hoe. So if you have the time and energy, it’s a weed that’s vulnerable to regular weeding patrols – unlike suckering perennial weeds such as bindweed and goutweed.
Hairy galinsoga plants also can be spot-sprayed with a variety of liquid herbicides if you’re able to spray them without drift blowing onto neighboring flowers or vegetables that you don’t want to kill.
Read product labels for safe use and to be sure the herbicide you’re considering is labeled for control of hairy galinsoga. Applications can be made any time the foliage is green and growing.
Hairy galinsoga flowers. iNaturalist
Preventing future trouble
Since hairy galinsoga depends on good seed-sprouting conditions each season, one prevention strategy is limiting tilling, digging, and disturbing the soil surface as much as possible.
Sprouting also can be discouraged by covering bare soil with mulch.
Another option in non-edible gardens is heading off seed germination by scattering a granular weed preventer over the beds.
Preen Extended Control Weed Preventer is labeled for the control of hairy galinsoga in landscape beds, where it can be applied after planting annual flowers or over top of some 600 species of existing landscape plants. The label lists plant-by-plant specifics.
For best results, lightly water after scattering the granules.
An early-spring application of Preen Extended Control Weed Preventer can prevent hairy galinsoga (and more than 100 other common weeds) from germinating for up to six months.
Preen Mulch with Extended Control Weed Preventer is a two-action bagged product that combines wood mulch with a weed preventer.
Preen One Lawncare is an option for controlling hairy galinsoga outbreaks in the lawn, along with preventing crabgrass and killing some 250 types of lawn weeds.
In vegetable gardens, young hairy galinsoga plants are best pulled ASAP, and new ones can be prevented by mulching with straw or leaves between vegetable transplants or between seeded plants once they’re up and growing.
In all cases, it’s important to eliminate any existing hairy galinsoga plants before they have a chance to flower and produce seed to create even more trouble next year. Though plants produce thousands of seeds, most fallen seeds survive for only two to three years in the ground.
