Annual Weeds

Relatively few of the Idaho noxious weeds are annual plants, but many of the worst of our obnoxious weeds are. The basics: an annual plant is one that usually goes through it's life cycle, from seed germination to seed production, in one year and then dies. Most garden vegetables and bedding plants are annuals which is why we have to replant them each year. For annual weeds, the good news is that to control them all we have to do is prevent seed production and keep new seeds out and they will be gone. Of course it isn't this easy or they wouldn't be the problem plants that they are. The bad news is that all of the annual invasive weeds have adaptions which make them very successful survivors. Generally this means production of huge numbers of seeds that survive well and are widely spread. All of the "tumble weeds" are annuals which spread seed as they tumble across the landscape. In northern Idaho, Kochia is one of these. Cheatgrass produces seeds that survive fire and attach to the fur of animals (and people). In our area, the only annual noxious weed is yellow starthistle, which produces seed that can stay in the soil for up to 12 years. One of the basics for control of all problem weeds is to prevent seed production, but this is especially true for the annual weeds. Don't let them flower! This pic shows young green cheatgrass seedlings growing under last years dead plants (their parents). Note the green carpet look of the young plants. Sorry about the photo quality.