I would like to grow some “barometer plants” to use as an early warning system for my garden. What plants are first to respond to frost, first to bolt and first to wilt? Is this a waste of time? It’s not a waste of time, but I’m not sure you’d have to invest in any particular variety. I would use half-hardy annuals that are sensitive to frost, such as cosmos lobelia
The best weapon you have against this annual weed is crabgrass preemergence herbicide (also called crabgrass preventer). You apply this product in the spring before the crabgrass seed sprouts. This granular herbicide works by creating a chemical barrier at the surface of the soil. As the seeds begin germination, they take in the herbicide and die.