In terms of prairies, and plant life in general, October is the month that separates the cool season plants from the warm season.
Warm season plants are those that thrive in the warmer temperatures of summer, but begin to go dormant when the cool days and nights of autumn arrive. The cool season plants are those that thrive in spring and fall. October is the month that separates the sheep from the goats, as it were, like no other month [the metaphor has its limitations as in the biblical account (Mathew 25:31-46) judgment is rendered on the goats, who will not enter the kingdom of heaven, whereas the sheep do].
Here are some examples we’re seeing these days:
Knowledge of cool season versus warm season plants is very important for prairie restorationists in particular, and anyone who deals with plants in general. This is because knowing the activity of a plant can help one decide when to apply fertilizers or herbicides, or indeed when to plant.
For example, October is the month that we’re out spot spraying Reed Canary grass in prairies. We spray now because the natives are shutting down and are not affected by the herbicide, whereas the cool season non-natives take in the herbicide.
Another example is lawn seeding. As said before, bluegrass and fescue, both lawn turf grasses, are cool season plants. So by seeding them in September, one can do so without extra watering, partly because the sun is low, and the moisture stays in the soil. The upshot is that, by seeding in the fall, one need not purchase and install a sprinkler system. The grass will come up on its own quite well.
Of course some grasses do better with less water in the long term than others (such as fescues, as opposed to Bluegrass), so thought needs to be put into that.
Paying attention to cool season and warm season plants is not only interesting, but can make the difference between installing a $5,000 irrigation system, and not installing one at all.