Weeds. They’re on every gardener’s list of woes. We often have clients come into the office asking for a weed to be identified. Then the next thing they ask is how to swiftly eradicate just that one weed from their landscape. “I don’t really mind the rest, but THIS ONE has got to go” is something we hear on repeat. If only it were that simple.
The most effective way to eradicate just one particular weed from the landscape is to get down on the ground with gloves and a trowel and pull them out them one by one. But that is hardly a desirable option for the exasperated gardener who inundated with these plants-out-of-place.
An alternative option is to individually spot treat each and every one with herbicide, being careful not to spray anything else. Herbicides come in two types: selective and non selective. Selective herbicides are designed to work selectively on entire classes of weeds from broadleaf to grassy weeds and sedges. So if you have a particular broadleaf weed that you want to eradicate and you broadcast an herbicide labeled for broadleaf weeds it is going to take out ALL the broadleaf weeds not just that one. A non selective herbicide will work to kill everything that it comes in contact with-including the desirable plants that you are cultivating such as turfgrass or ornamental plants.
As the cooler weather gives way to a warmer season here in NE FL, I’ve noticed the population of weeds shifting. Here are a few I’ve been seeing recently in my landscape that you may recognize from your own.
Wild Geranium – Geranium carolinianum
Native, broadleaf
Tiny whitish pink flowers are a favorite of bees and the seeds are a food source for birds.
Control: Easy to hand pull. Pre or post emergent herbicide. https://mrec.ifas.ufl.edu/research/weedsbyflowercolor/pinkorblue/geraniumcarolinianum/
Pink Woodsorrel – Oxalis Debilis
Non-native, broadleaf. Often misidentified as clover due to its cloverlike leaves.
Showy pale purple-pink flowers
Control: Spreads by seeds, rhizomes and forms bulbs. Hand pulling is the most effective but it’s imperative to dig out all parts of the root, rhizomes and bulbs underground or it will quickly reappear. Post emergent herbicides can control the leafy growth but repeated applications may be necessary for this aggressive weed species. https://plant-directory.ifas.ufl.edu/plant-directory/oxalis-debilis/
Common Yellow Woodsorrel – Oxalis stricta
Native, broadleaf. Often misidentified as clover due to its cloverlike leaves.
Small yellow flowers
Control: Hand pulling. Pre and post emergent herbicides. Fibrous root system with taproot. Will re sprout from stolons, rhizomes, or root and stem fragments left behind in the soil. Often a nuisance in containers and nursery pots as well as in all areas of the landscape. In studies, oxalis have been shown to negatively impact the growth rates of container grown plants. https://edis.ifas.ufl.edu/publication/EP514
Asiatic false hawksbeard – Youngia japonica
Non-native, broadleaf. Often mistaken for dandelion as the low growing leaves are similar and flower color is the same.
Yellow flower clusters atop a long, thin stem.
Control: Hand pulling the entire plant and roots, ideally before the seeds appear. This plant will regrow from roots left in the soil. Preemergent herbicide is most effective. Treating this aggressive weed species after it has established is difficult and often requires non-selective post emergent herbicide. A major nuisance in potted plants, nursery pots and throughout the disturbed landscape. This plant produces abundant seeds that are easily dispersed by the wind. https://edis.ifas.ufl.edu/publication/EP636
Black Medic – Medicago lupulina
Non-native, broadleaf. Often misidentified as clover or perennial peanut.
Round yellow flowers
Control: Pre and post emergent herbicides. Hand pulling is very effective; ideally before seeds appear. Mainly a problem in bare areas of the landscape and in unhealthy turfgrass. https://edis.ifas.ufl.edu/publication/HS1319
Florida Betony – Stachys floridana
Native, broadleaf
Pale violet flower spikes are a favorite of bees.
Control: Hand pulling and post emergence herbicide can be effective. Since this weed reproduces from underground tubers, you must completely remove all tubers when hand-weeding. Florida betony produces rhizomes and edible pale-white segmented tubers that look similar to a rattlesnake’s tail. Once established, Florida betony is difficult to remove by hand because the tubers and rhizomes break easily, and small root fragments can regrow. https://edis.ifas.ufl.edu/publication/EP597
Knowing when weeds emerge is important for executing effective management techniques.
In order for preemergent herbicides to work they must be applied before the target weed seeds germinate. In NE FL, one application in late February or March will control most warm season weeds, while a separate application in October will control most of the cool season weeds we are seeing now.
A few considerations for a Florida-Friendly landscape:
- Whenever possible, hand pull weeds.
- Always spot treat vs broadcast your chemical control. This will save you money and time, as well as drastically reduce your environmental impact.
- In many cases, the first line of defense against these weeds in turfgrass is to use cultural practices that promote vigorous turfgrass growth and development. Weeds do not readily infest turfgrass that is properly fertilized, watered, and mowed at the correct height and frequency. For more information on the best cultural practices for turfgrass see the Florida Friendly Landscaping Handbook for Home Landscapes.
- The ground is a seed bank, full of weed seeds waiting to germinate and of bulbs and rhizomes capable of multiplying when fragmented. For this reason, when working in the landscape, aim to disrupt the soil as little as possible.
- Using an organic Florida-Friendly mulch such as pine bark will suppress weeds in flowerbeds and along pathways.
- Do not add plants that can regrow from fragments, rhizomes, or bulbs to your compost bin.
Whether you call them weeds or wildflowers, there are pros and cons to having these plants in our yards. Live in Duval County and need help identifying weeds popping up in your landscape? Drop by with samples, or email a few clear photos to our Master Gardener hotline duvalmastergardener@gmail.com M-F 9am-3:30pm. Our Master Gardener Volunteers are eager to help you learn more about what you’ve got growing!
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