Spring Bloom in Fall--It's a Problem

In today's SF Chronicle (January 1, 1917), I wrote about plants that bloomed last fall in San Francisco that ought not to have been blooming until spring, caused by continuing climate change.

While it's true that we typically have our warmest "summer" weather from mid-September to mid-October, this weather has been lasting longer than usual. Last fall, the warm days and mild nights lasted until near the end of November. We celebrated time spent outdoors in nice weather, but some of our garden plants reacted by blooming and leafing out as if it were spring. This is a problem for the plants, which put energy and physical matter into doing this, so that when spring really does come, they have less stored matter and food energy to do it all again. This weakens the plant, leaving it more susceptible to all kinds of setbacks.

Case in point is my apple tree, which has borne bountiful crops of delicious apples for 30 years. But recently it has been trying to bloom in fall. Then, because winters aren't quite cold enough, it blooms later than usual in the spring. And, because of the energy it used up in fall, it blooms more sparsely. Two years ago, it had practically no fruit.

Last year it did better, though not as well as it used to do. The photo below, which I sent to the Chronicle, but they didn't use in the paper, shows my tree last November, with a few last apples and last leaves till hanging on while blooms and new leaves opened all around them. Now, on January 1, all the new leaves have succumbed to cold, wasting all that effort.

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If you are growing other temperate plants in the Bay Area, such as cherries and plums (ornamental or fruiting), magnolias, lilacs, or azaleas, you may be having the same kind of problem. What's to be done to save our plants? Obviously continue to work against climate change, a movement in which California in general is doing well.  But we can also join an effort to record the changes, in which our regional data will provide extremely valuable evidence.

More data about how climate change is affecting plants in our region is especially important so that we are represented in a system that has so much more data from cold-winter regions.

There are two organizations that are seeking citizen science data. One is the National Phenology Network (www.usapn.org/), sponsor of the National Phenology Project. It studies both plant and animal species. Another, Project Budburst (budburst.org), is studying only plant responses. Phenology is the study of what plants and animals do in response to seasonal changes.

Sending records to these databases is easy to do online. Log in, choose a plant, and tell them what it is doing on various dates. Children can do it at home and school classes can do it. Both web sites have curriculum information to help teachers fit the work into classes. It teaches observation, appreciation of plants, climate science, ecology, and how science is done

So as our new, and rather unnerving, year begins, please help observe and record what is going on with nature. Your reports will be powerful.

Some Plants Think it's Spring this November!

Well, we know they aren't thinking, and I guess that's the problem. When San Francisco has some cold weather followed by a period of warm days in mid-Autumn, some plants start growing, or blooming, as they would normally do in February or later. We see a few plum blossoms in fall sometimes, but this year I am seeing many blooming plum trees. I even saw a blooming crabapple tree yesterday, and they normally bloom later in spring than the flowering plums!

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Looks like spring, doesn't it. But look enlarge the image and you see the fake spiderwebs on that tree that remain from Halloween. This shot was taken on November 15, 2012.

In my backyard, I cut a bulbous iris and put it in a vase in early November. This is definitely a February flower, but three plants have bloomed and the rest are all and still growing.

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You can see one of the last ripe apples still hanging on our tree. Wrong time of year for iris, for sure.

Another plant reacting badly is the Crocosmia 'Solfaterre'. It had its deep yellow flowers in September, then died back, and I cut it to the ground. Didn't expect to see it again until maybe March. But here it is again, with leaves popping up in November! (The leaves start out green, but turn a smokey brown by midsummer.)

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The problem, for these and other early growing and blooming plants is that they are using up all of this energy now, and will probably be forced back into dormancy by colder weather in December and January. Thus they will have less energy to grow and bloom in the spring.

Global warming may change what we can successfully grow here. Some plants that depend on just enough winter chill to rest and regrow, may not thrive if our climate shifts just enough to make them try to bloom twice a year.

The study of the relationship between climate and natural phenomena such as flower bloom time is phenology. We're going to hear a lot more about it as the earth warms!

I was out gardening today, making Black Friday into a green one. A peaceful day. I deadheaded the Cosmos, which are still blooming madly in both front and back yards, then cleaned up apple leaves under our tree, to get rid of apple scab spores. Tomorrow I'll put some composted chicken manure on the wild onion (Allium triquetrum) bed to help them get growing faster. I've been watching the madness at stores on TV and being glad to be home today.