What are "winter weeds"?
The term "winter weeds" refers to the small plants that spring up in your garden surprisingly in late fall and early winter when most other plants have died or are dormant. They may stay small all winter or proliferate rapidly if the weather is warm. They will usually stay small throughout the winter and then grow, flower, form seeds and die in spring and early summer.
Some examples that you will find in the Northeast are: deadnettle (Lamium purpureum), henbit (Lamium amplexicaule), common chickweed (Stellaria media), Persian speedwell (Veronica persica), bedstraw (Galium aparine), and shepherd’s purse (Capsella bursa-pastoris). Gardeners should manually weed out these plants as soon as they start growing so that they don't set seed the following year.
Courtesy of the NYBG Plant Information Service