Current Nature: Why Your Garden Is Back In Bloom

Anyone else still sweating? It’s been an unseasonably warm fall, and it’s had some weird effects on our local plants. Many people have noticed that the plants in their yards have flowered for a second time and that some have started to produce new leaves. So what exactly causes this, and how will it affect the health of not just our plants but our entire ecosystem?

When we observe plants blooming or creating new leaves at an unusual time of year, what we are observing is abnormal phenology. Phenology, the study of nature’s timing - from the blooming of flowers to the falling of leaves - is a major research focus of ours at the Linda Loring Nature Foundation. We typically envision plants growing leaves in the spring, flowering some time between May and September, then soon after creating fruit and seeds before going dormant for the winter. Many plants, however, don’t naturally follow this pattern. Some plants that are starting to leaf out now will be able to maintain their leaves for the whole winter, then, as soon as conditions are right, they will be ready to grow and produce flowers. Other plants start growing at the end of winter/ beginning of spring while the mornings are still frosty. These plants are equipped with antifreeze and are among the first to flower in very early spring, providing essential food to the first active pollinators of the year.

There are some plants, such as lilacs, roses, and blueberries, that have started to flower and leaf out now on Nantucket. This is an unusual occurrence for these species at this time of year. Warm temperatures have extended so far into the season that these plants are tricked into thinking it’s spring. So, will this hurt the plant? Well, they have just spent the last few months creating buds meant to bloom after winter, and since these buds are blooming now, you might not see these plants flower again in the spring, but it’s unlikely to kill them.

Atypical blooming time could have repercussions for our ecosystem. At this time of year, few pollinators are still active. Without being pollinated, these plants won’t be able to set seed and reproduce. Many insects also specialize on these flowering plants, which means that they will only use those flowers or leaves for food. If some plants aren’t able to produce flowers or leaves in the spring due to premature blooming in the fall, some pollinator species could be left without a food source and die. If patterns of early blooming continue, we could see large declines in many plant and insect populations.

So why did this warm weather only trick certain plants? Most plants in this region use temperature changes as cues to know when to produce leaves, flowers, fruit and drop their leaves. In the winter, some plants will simply wait for the temperature to warm up before growing leaves, but many others have a chill requirement. They need to experience a long cold period after they’ve dropped their leaves before they can respond to warm temperatures by growing leaves. That’s why plants such as cherry trees and black huckleberries aren’t growing new leaves or flowering right now despite the warm weather.

This weird phenomenon is directly related to global climate change, the effects of which have become increasingly evident in recent years. Scientists like us are working hard to understand exactly what this means for our ecosystem and our gardens. Want to help? Documenting any weird plant phenology that you see is incredibly useful for this research. One great way to do this is through iNaturalist. Using their app, you can take a picture of what you want to identify, and they will suggest possible species, then you can upload the observation for researchers to find. You can also log in on your computer and further annotate your observation to include the stage it is in (e.g. marking a plant as flowering). If you want to be more involved in tracking the phenology of a plant, you can also collect data for the National Phenology Network using Nature's Notebook. This is a community science project where people all around the nation track changes in plants and animals. All you need to do is pick a plant or animal from their list that you can visit regularly and answer a series of questions about the current stage it’s in each week. Like iNaturalist, all this data is available to researchers.

While it can be frightening to see the effects of climate change happening in your own backyard, it is important to keep in mind that the science community is working hard to learn about its effects and how to plan for it. We encourage you to report abnormal findings to help further these efforts, but to stop and smell the flowers, too!

Stay tuned for more editions of Current Nature, a bi-weekly column featuring seasonal topics, natural history information, and advice on the outdoors from the staff at the Linda Loring Nature Foundation.