The Weeds of Spring Get Their Start in Winter
How 5 common winter annual weeds get established in your garden and how to control them.
The end of the growing season doesn’t mean the end of controlling weeds. Fall and even winter are two of the best times to prevent weeds.
Three kinds of weeds are especially good targets in the off-season, including:
These are weeds that germinate from seed in the cool soil of fall and early winter, then grow and flower early the following year. A few perennial weeds (ones that grow on their own roots year after year) also can germinate in fall, such as dandelions and plantain.
Since winter annuals sprout each year from seed, the best way to control them is to prevent them with a late-summer or early-fall application of a weed preventer, such as Preen Extended Control™ Weed Preventer.
This granular product stops many common winter annuals, such as chickweed, hairy bittercress, henbit, marestail, prickly lettuce, shepherd’s purse, and speedwells, from appearing in the first place without harming most existing plants (meaning it can be applied in existing landscape beds). One application gives winter-weed protection for up to six months (see Use Directions for a complete list of treated weeds).
Preen doesn’t kill existing weeds, though, so if you’ve waited too late to apply or already have weeds up and growing (including perennial weeds), you’ll have to pull those or use an herbicide (weed-killer) when temperatures are above freezing.
Biennials are plants that sprout from seed and grow leaves the first year, then overwinter to flower, drop seed, and die in the second year. Examples are thistle, poison hemlock, wild carrot, knapweed, burdock, teasel, garlic mustard, and mullein.
Most new biennial weeds can be prevented using the same Preen Garden Weed Preventers as annual weeds* (*see Use Directions from a complete list of treated weeds). But once a biennial is up and growing, it’ll have to be dug out or treated with an herbicide – ideally when as young as possible.
Herbicides can be used on these in fall on above-freezing days but only so long as the plants are still green. Biennials that have died back and gone dormant for the season can be sprayed early the following spring, once growth has resumed.
What’s especially important with biennials is preventing these weeds from going to flower in the second year. So even if they’re not completely killed or removed, if you cut off or mow any flower stalks before seeds have had a chance to mature, you’ll end the plant’s two-year life cycle.
These are woody weeds that grow year after year and produce woody stems or trunks that can get very big over time. Examples are tree of Heaven, multiflora rose, autumn olive, Japanese honeysuckle, poison ivy, porcelain berry, Oriental bittersweet, wild grapes, and Japanese barberry.
Fall and winter are good times to cut down invasive shrubs and weedy vines because the leaves have dropped from most, making them a bit easier to see and reach.
Watch in spring for these cut-off plants to try and resprout or send up new shoots from underground runners. Keep cutting new growth until the plant “gives up.”