After exploring resources about plant life cycles, the big piece I was missing was how perennials like herbaceous perennials and woody perennials survive the winter and if there are differences between them. I found out that the process is very similar for both. The main difference is that woody perennials, like trees, drop their foliage but the woody parts survive year after year. For herbaceous perennials, the stems and leafs die off in autumn while the roots survive underground.
I had to give myself a photosynthesis review by reading a Smithsonian book my son has about various science topics. I'm sure I had to learn about it growing up, but I did not remember the details of the process! What I learned is that perennial plants use the nutrients they generate during the summer to develop the parts of themselves that will last through the years, and to store nutrients. In autumn, the reduction in sunlight signals them to prepare to rest for the winter. As the leafy parts change colour and fall, the hardy parts of the plant slow down. It strikes me as very similar to animals that hibernate for the winter.
What I didn't know about is how perennial plants produce their own "antifreeze"! They are adapted to prevent the water from freezing in their cells, which could cause death. For deciduous trees, the wood of their trunks and branches is tough enough to protect the plant through the winter. For herbaceous perennials, the temperature underground is more stable and mild which enables survival. If the ground is covered, say by the dead leaves and plant material from fall, these underground parts are further insulated from the cold. Evergreen trees are a bit different because they don't drop their leaves. If we're speaking about our local evergreens, they have tough leaves (pine needles) that can withstand the colder temperatures. They still slow down during the winter, but don't go completely dormant.
In the spring, perennial plants have the advantage of earlier growth than plants growing from seed because they already have an established foundation and stored nutrients. They just need a cue from the sun and warmer air temperatures to begin growing again.
Learning all of this made sense to me. For the most part it was not new, and it was mostly what I expected. Researching allowed me to round out my knowledge and in the process add some unexpected information, like the "antifreeze" part.
Resources:
https://extension.unh.edu/blog/2018/12/dormancy-key-winter-survival
Book: Smithsonian's Science! by Abigail Beall, Jack Challoner, Adrian Dingle, Derek Harvey, Bea Perks