Valentine’s day is on the horizon and grass in panhandle Florida’s yards has finally stopped growing, so the lawnmower can be stored for the winter. The milder (sometimes cold) days and cool, crisp evenings signal a pause for turf weeds until the weather warms up again in the spring, right? Well, not quite.
A quick look around the landscape reveals small, unplanned plants breaking the surface of the soil. While the warm season weeds have gone to seed and the turf grasses are dormant, winter weeds are just getting started.
Some of the culprits are classified as non-native invasive plants, introduced in the relatively recent past by accident or intentionally. Others are noxious natives which have existed here for eons, but because of their traits, have never achieved the desirable designation of landscape shrub.
Vetch is a native plant which thrives in north Florida’s cooler months. The tiny seed pods deliver abundant seeds which are germinating now and can produce a tangled thicket of delicate green plants for yards and landscapes locally.
Their flora status notwithstanding, they have a limitless supply of vigor and hardiness. Their ability to flourish with minimal inputs under hostile conditions is the envy of plant breeders worldwide.
If propagated by seed, a winter weed’s seed may be deposited by birds, animals, wind or water, then lay dormant for months, years or decades. When conditions are just right, the seed germinates, usually in-force, and ambushes the homeowner with an unexpected problem.
Similarly, if the winter weed is spread by rhizome, it will stealthily wait during the warmer months, hidden by warm season shrubs and grasses just below the soil’s surface. The change to cooler weather will initiate breaking cover and a full-fledged lawn invasion by assaulting weeds.
The alert homeowner may notice an early rhizome-based trespasser and pull it up. Unless all the roots come with the recently-departed weed, the offending plant will rise from the dead quicker than a zombie in a Hollywood horror movie.
The first step to controlling this problem is to identify your weeds, then choose the appropriate and effective treatment. The homeowner needs to select a treatment option which best suits their individual needs and goals.
Pre-emergent herbicides form the basis for a chemical weed control program in turfgrass and are used primarily to control annual grasses and certain annual broadleaf weeds. As the name indicates, pre-emergent herbicides are applied before weed seed germination.
Sufficient knowledge of weed life cycles is important when herbicide application is timed to attempt pre-emergence control. If the chemical is applied after weed emergence, these herbicides will have little effect. This narrow window of application timing is a potential disadvantage for many homeowners, who commonly wait too late.
Post-emergence herbicides are active on emerged weeds. Normally, the younger the weed seedling, the easier it is to control. Post-emergence herbicide effectiveness is reduced when the weed is under drought stress, has begun to produce seeds, or is mowed before the chemical has time to work.
Another tactic is over-seeding with annual ryegrass which can provide some suppression and control of many winter weeds. Winter over-seeding has the added advantage of a level of protection from freeze damage during extreme cold periods.
Lastly, the homeowner can let the annual weeds provide a “natural look” to the lawn in winter. Cool season annuals, like clover and vetch, have the added benefit of contributing nitrogen to the lawn.
The lawn mower may get a reprieve, but homeowners must be ever vigilant. At least watching the weeds is a good excuse to go outside and enjoy the cooler days between playoff games.
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