Petunias still going strong in the author’s Alexandria garden. (Adrian Higgins/The Washington Post)

I keep telling myself that any day now the clay soil will be rock-solid frozen, or at least the garden will be iced with a hoar frost. But the day never comes. Instead, I give the lawn yet another mowing and rue the fact I didn’t overseed the turf in September, in a fall that just keeps rumbling along.

We have had lingering autumns before, but I cannot remember a December when petunias and begonias were still blooming in their pots and the tropical water lilies were offering up their flowers, albeit feebly.

The balminess has caused strange confluences. One of the last plants to bloom in my garden is a hosta named, appropriately, Tardiflora. It forms a ground-hugging clump of narrow pointed leaves, and just when you think this shade perennial will never flower, it sends up a spike or two around Halloween and sports blooms in a light but rich purple. Unlike other hostas, which have melted away, this tough and tardy hosta still sports attractive foliage. This year, it is still flowering.

The snowdrop is one of the first plants to kick off the growing season, appearing in this part of the world in early March. But in my garden, which has seen two light frosts, the last one this past weekend, a snowdrop has erupted from a little patio bed of boxwood. I planted it a few weeks ago, and it may have been thrown off by this act — snowdrops are best moved in leaf, after flowering. But the fact that the two bookends of the growing season are flowering together is an indication of just how odd things are this year.

Wax begonias and dracaena are supposed to be done by now. (Adrian Higgins/The Washington Post )

These little events occurred the same week the world’s leaders were in Paris, pledging once more to address the existential problems of greenhouse gas emissions and climate change. Gardeners, as a class, are well equipped to take note of a shifting environment and do something about it. The more plants we cultivate to maturity, the more we cool the city and inject oxygen into the air. The more food we grow organically ourselves, the smaller our carbon footprint.

Clouding our ability to sense a changing climate is the fact that Washington has four distinctly different seasons and that no year is quite like another. Our weather patterns, between mountain and ocean, between north and south, have none of the relative constancy of other places. For the gardener, this keeps it interesting. However entertaining we find this volatility, though, the underlying climate trajectory is worrying. This year is expected to be the warmest ever recorded globally, after years of higher average temperatures.

For the autumn gardener, this year’s long goodbye may be viewed as consolation for a growing season that was trying, to say the least. Spring floods were replaced by a summer drought.

Well into the last month of the year, it is somewhat astonishing that certain plants not only are hanging onto their leaves but also are still green. I’m thinking of a hydrangea relative, a vine named schizophragma, which is only now thinking about yellowing up before the drop. A true hydrangea, H. aspera, is still fully covered in its deep green velvety leaves. The king of the hydrangeas this fall has to be the lovely, coarse-leafed oakleaf hydrangea, whose leaves go through a succession of pinks to a deep maroon. The five mature shrubs I have are at every point in their spectrum, still.

The Asian maples are similarly in no rush. A young weeping threadleaf acer is crimson, October style, and a paperbark maple has developed bicolored leaves of rose and apple green. This little tree is so much better than the sickly and stubbornly underperforming stewartia it replaced. The bark, which is a deep, warm brown, peels decoratively, making the tree — botanically Acer griseum — one to behold in winter, if it arrives. Get yourself one.

The abelia bushes have never been more floriferous and are covered in picnicking honeybees. A dwarf bearded iris has erupted into flower, which is not that odd when you consider there are varieties bred for their repeat blooming in the fall. I’m told this was a banner year for reblooming irises.

Oakleaf hydrangea leaves darken to maroon, in their own time. (Adrian Higgins/The Washington Post)

The mildness is not without its worries. If you peel back the leathery leaves of the Lenten rose, you can see that next season’s growth is stirring from the crown. This normally occurs any time between late January and early March, depending on the winter. What you don’t want now is tender new growth before the January freeze. The only course is to keep this year’s leaves on the plant to act as a protective cover. The fig tree, knocked back by two hard winters, is still in full leaf, another vexing sign that it isn’t looking at the sky and bundling up to hibernate.

One place where the protracted autumn is a boon is in the community garden. The September-sown mesclun mixes, mustard greens, kale and collards are in their element. The lettuces, rigged to receive a row-cover blanket on the coldest nights, will provide fresh salads until the end of the year or longer.

I spent a recent afternoon there turning beds that were empty save for a few weeds, preparing them for next spring without the worry that if I left the task until February, the ground might still be frozen.

The afternoon was damp and cold, but not unbearably so. How much more pleasant than working in the middle of summer, when you must stop to mop your brow and slather on the sunscreen and insect repellent.

@adrian_higgins on Twitter