Question: I’m confused by weedkillers. There are so many types. Can you make some sense of them for me?

Answer: You’re right. There are many different types of weedkillers. That’s because there are many different categories of weeds. The interesting thing is, you don’t really have to know exactly what weed you have, so long as you can put into the right categories.

To explain:
1. Is it an annual weed, or does it come back as a perennial, year after year from its old root system?

2. Is it a grassy type of weed, or is it a non-grassy (“broadleafed”) plant?

3. Does it do most of its growing in the late spring and summer (“warm-season” weed), or is it most evident from late winter into mid-spring (“cool-season” weed)?

If you can answer those three questions, you can pick the right weedkiller. To illustrate further, for annual weeds you can use a pre-emergent weedkiller before their seeds start to sprout. These are generally granular materials, and prime times of application would be in late winter, again in late spring, with both of those treatments aimed at the summer weeds, then in early to mid-September for the cool-season annual weeds. You will need to use post-emergent granules or sprays to eliminate existing weeds that you can see in your landscape. There are broadleafed post-emergent sprays and granules, and there are a few post-emergent sprays for grassy weeds, although some of the most effective types are no longer sold. Your local nurseryman can show you several options.