In the age of climate change, gardeners must become more attentive and flexible. (iStock)
Gardening columnist

Some gardeners are telling me that the tulip display is coming up short, literally. Blooms that should be hovering as high as three feet are at about two.

The reason for this may be linked to the spikes in temperatures in February, the warmest on record for Washington. This, in turn, may have denied tulips the amount of uninterrupted cold temperatures they need for proper development.

Is this connected to climate change? Probably. In the decades I’ve been gardening in the Washington area, I’ve seen winters get warmer and shorter, summers longer and hotter, and the arrival of new pests and diseases. This was the first winter I remember February swapping places with March. I’m told I should get used to it.

The harlequin bug, once a destructive (if pretty) insect of the lower South, is now a regular visitor to my cole crops. My fishpond doesn’t have alligators or wood storks yet, but it’s still fairly early in the week. Sweet corn, tomatoes and pepper plants, once the very stuff of summers, are now stressed by too much heat. The Japanese banana plant barely needs a light mulch to return after a winter in the ground, and pomegranate trees are doing fine, thank you. In Georgetown, the agapanthus, from Africa, is emerging from the ground. Rose bushes in protected city gardens continued to grow through the winter with no seasonal dormancy, until the freeze in March zapped the tender growth.

Virginia bluebells used to flower at the end of April in these parts; now they appear at the beginning. The same is true for lilacs.

Virginia bluebells near Clifton, Va., on April 14. Once an event of late April, the flowering now occurs much earlier in the month. (Adrian Higgins/The Washington Post)

These empirical realities are underpinned by scientific data showing that in recent decades, the oceans have warmed rapidly, the ice sheets are melting and the weather is more extreme, and experts believe that greenhouse gases from human activity are behind it.

This is accepted science in most of the world, but in some corridors of power in Washington, skepticism rules. President Trump has called climate change a hoax, and his head of the Environmental Protection Agency, Scott Pruitt, has stated that he doesn’t think human-fueled greenhouse gases are “a primary contributor to the global warming that we see.” Pruitt is a politico from Oklahoma, a state where the oil derricks are (at least) as high as an elephant’s eye.

On April 22, Earth Day, organizers of the March for Science will hold a rally and march on the Mall in opposition to the administration’s stance on science, climate change and related public policy.

A week later, a group named the Peoples Climate Movement has planned a demonstration outside the White House in opposition to the president’s “attacks on our climate.”

Gardeners, meanwhile, can think globally but act locally, one of those platitudes that has kept its cogency.

“There aren’t many areas of our lives where we have control, but we have pretty good control over what we do in our yards,” said Sara Via, a climate change specialist with the University of Maryland’s extension service. “There’s an astonishing number of back yards in America.”

Together, they have 42 million acres of lawn — “more than the acreage planted in corn. People ask, ‘What can I do?’ One thing you can do is phase out your lawn,” she said.

She said gas-powered lawn and garden equipment produces a significant amount of carbon pollution. In addition, synthetic nitrogen fertilizers are made by burning lots of natural gas.

Fertilizer runoff pollutes waterways but, as it breaks down, can also add to air pollution. When it comes to nutrient runoff, homeowners pollute at a rate 10 times greater than farmers, said Via, “because homeowners don’t know what they’re doing.”

Another way to reduce your carbon footprint is to grow your own fruits and vegetables organically. The right tree, well placed, can shade your house and further reduce your energy consumption.

“Mention climate change and people just want to put their head inside the pillow, but if you say, ‘Here’s what you can do,’ people say, ‘Yeah, let’s try something,’ ” Via said.

For environmentally savvy gardeners, there is another problem — in distinguishing between freakish weather and climate change. Serious gardeners are so attuned to the vicissitudes of the elements that even the most extreme floods, droughts, storms and heat waves can be viewed as strangely normal.

“What people don’t recognize is that we have moved out of the territory of the kind of variation people are used to, and we are in new territory where it’s more extreme,” Via said. “Average temperatures have warmed, we have fewer colder nights — it’s not the same thing.”

Janet Young, of Montgomery County Master Gardeners, lectures on gardening techniques in this new environment. Because tomato and pepper plants reduce fruit set and suffer poor quality in extreme heat, she advises shielding them with shade cloth. Another approach is to sow winter cover crops in late summer as a way of excluding weeds (one of the plant beneficiaries of climate change) and enriching the soil without fertilizers.

Gardening simply requires greater vigilance than before; insect pests may have three generations a year instead of one, and you have to check them before they get out of hand.

“You may want to get out there and weed as early as January, instead of March or April,” Young said. She is working with others to develop a list of plant varieties bred for better tolerance to environmental stresses.

Another strategy is to expand the range of plants in your garden to include those that can endure more cold, more heat, more drought.

At the New York Botanical Garden, “we are incorporating plants from climates similar to ours but more extreme,” said Todd Forrest, vice president for horticulture and living collections. These include trees and shrubs native to the Caucasus and more plants from Southern states.

“I don’t know whether they will survive, but we need to broaden the palette of plants that might survive,” Forrest said. Unfortunately, the patterns of change are not simply a case of plants that once worked in Georgia now growing dependably in Washington, he said, “because you’re still going to have colder weather than Atlanta.”

“There is no easy answer,” he said. “Be a better-informed gardener, be willing to experiment, pay attention to changes and talk to other gardeners.”

Another response is simpler — pause to savor, say, an April shower or a fresh spring morning that requires a sweater. “As a gardener, when we have a beautiful or seasonal day, I tend to be thankful for the rare experience of normalcy,” Forrest said.

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