When Winter Arrives, These Unwanted Plants May Spring Up

Cool-Weather Weeds

Q: After spending most of the summer and fall getting my lawn in good shape and killing the weeds in it and in my planting beds, I have a new problem: Different weeds have sprung up. What am I doing wrong?

A: Since I don’t know for sure what you’re doing, I can’t say you’re doing anything wrong. But I suspect what is happening with your lawn is simply Mother Nature shifting into a new season here in North Florida. Just as certain herbs are warm-season plants and others are cool-season plants — basil needs heat, parsley needs cool — so it also goes with weeds.

For seasonal weeds, you can do a lot to control them for the next cycle if you remove them before they flower and the wind sends the seeds all around your yard. For plants that creep, such as purslane, dig them out shortly after they sprout, while they’re small. It’s labor intensive and a lot of people would rather grab a bottle of herbicide, but that can bring its own set of problems, including toxicity to people and pets.

Many herbicides, particularly those with glyphosate, such as the Roundup brand, are “broad spectrum.” That means they don’t pick and choose between the plants you want to keep and the weeds you want to get rid of.  They’ll have a negative effect on everything they touch. Don’t be tempted to use a lawn “weed and feed” formula, because this is not the time of year you want to encourage growth. Plus, fertilizing feeds the weeds as well as whatever plant — turf grass, flowers or shrubs — you’re tending. If you decide to use a weed killer, be sure to read the label carefully and make sure it’s safe to use on and around your specific types of plantings. Don’t overdo it.

Here’s a list of some of the most common cool-season weeds in our region, USDA Zone 8b:

Carolina geranium: Geranium carolinianum is a multi-branched, low-growing weed with hairy stems and small leaves that resemble the Pelargonium geranium that is so popular in hanging pots. It reproduces by scattering its seeds to the wind. Pull it up before it blooms.

Henbit: Low-growing, square-stemmed weed with dark green leaves and small purple flowers. It, too, propagates by seed.

Florida betony: Stachys floridana is a year-round weed that will take over if you turn your back. Also known as rattlesnake weed, it grows from segmented tubers; pull one out, another will sprout. Leaves are lance-shaped with rounded margins.

Lawn burweed: Soliva sessilis has narrow leaves that sort of resemble the tops of carrots. This one is especially common in sandy soils.

Shiny cudweed: Gnaphalium americanum grows in summer or winter. It has a rosette of shiny green leaves.

Purple cudweed: Gnaphalium purpureum develops from a rosette, too, into a tall, silvery weed with yellow flower clusters at the tip.

Corn speedwell: Veronica arvensis is a low creeper with two levels of leaves, the lower ones almost round with toothed margins and the upper ones smaller and narrower. Small white flowers sit on top of the plant.

The key to doing battle with all these weeds is not to give up. It might take several years to get rid of some weeds. With others, such as Florida betony, the best you can hope for is to battle to a draw. Keep in mind, however, that one person’s “weed” is another person’s “wildflower.” Some of your “weeds” might grow on you.

© 2015 Postscript Publishing, all rights reserved. Audrey Post is a certified Advanced Master Gardener volunteer with the University of Florida IFAS Extension in Leon County. Email her at Questions@MsGrowItAll.com or visit her website at msgrowitall.com. Ms. Grow-It-All^® is a registered trademark of Postscript Publishing.