Hello! It’s April, it’s going to be almost 90° F this weekend, and winter skipped us.
Well, we had like one cold week, but that was it.
Honestly, it’s had me worried. A number of plant species that are native to this area require cold stratification — in other words, they need a period of cold and some pretty big temperature swings in order to trigger them to germinate at the correct time. This includes a tree that’s very important to me, the bald cypress. They’ve evolved to need cold stratification because without it, their seeds could germinate far too early and die off in the middle of winter.
I have packets of seeds that I want to plant, too, that need to be sown within a narrow window of time. I’m talking when temperatures are cool (but not too cool), usually right around the last frost date. The trouble is… like I said, it’s going to be in the high 80s this weekend. Our official last frost date was a few days ago.
Now that I’ve gotten my complaining out of the way, there’s an idea I’ve been exploring.
I first ran into it when I was researching native hydrangeas. I love hydrangeas in general (my grandfather had a big hydrangea next to the house I grew up in, alongside a strangely persistent and hardy opuntia cactus), but they’re not really known for their heat tolerance. They are, by far, not the only plants that are going to suffer as temperatures increase either.
Smooth hydrangea (Hydrangea arborescens) is native to this area. They also prefer daytime temperatures in the 70s and require supplemental irrigation when it gets too hot and dry.
Oakleaf hydrangeas (Hydrangea quercifolia) are native to the Southeastern United States. In other words, they’re from the US, just a bit lower than where I live. Changes in average temperatures are expanding the range of some southern plants and animals, while driving others further north.
Unfortunately, there’s not much that a single person can do to keep their cool temperature-loving plants from suffering from this effect. It’s also debatable whether we should — landscapes are ever-changing and evolving, and state borders are artificial constructs that plants and animals don’t recognize. It may increase the resilience of the landscape to work with this shift, rather than against it.
For this reason, I’m experimenting with oakleaf and smooth hydrangeas. Experts point out that this area’s climate is slowly aligning with species that used to be relegated to more southern states. Blending some Southern species with Midatlantic species could help create a plant, animal, and fungal community that’s more resilient to climate change, and decrease the need for supplemental irrigation or treatment for diseases related to heat stress.
Saving seeds from the individual native plants that seem to struggle less with the heat can help their species adapt over time, which will feed and protect the native animal species that depend on them. Adding in native-ish species from a bit further south can help the land adapt. It also ensures sources of food and nesting sites for the animals that are also being driven north as temperatures rise.