The Seattle region's coldest April on record is a boon for moss

Chilly?

That doesn't begin to say it: Seattle is shivering — enduring the coldest average high temperature for the first half of April on record at Seattle-Tacoma International Airport. And there's no end in sight, the National Weather Service says.

The Februarylike weather has been sticking around, even as rainfall this month has come in at about 3 inches — more than what usually falls in all of April.

Blame it in part on the jet stream, parked to the south, bringing a cool western, northwesterly flow of air our way, and allowing disturbances to ride into the southern states, including deadly tornadoes in the Southeast.

For us, this weather is just a vector for spring fever, with warmer temperatures teasing us during brief sunbreaks amid implacable clouds.

It's all relative, of course. Our crummy spring is a glory for that signature denizen of Seattle: moss. The glorious green yang to our gloomy gray yin, moss is reveling in all this cool, moist weather.

Moss is on the move everywhere: Its tender leading edges are creeping up benches, tree trunks and curbs, as moisture stokes its growth. And the cool, wet weather that has people buttoning their coats and turning up their collars has put moss in the mood for love.

Moss depends on rainwater to rinse the fruits of its ardor from male plants to female. In addition to growth and reproduction, moss also depends on rainwater to cater all the nutrients on which it subsists, for moss has no roots with which to reach out and get a meal.

This is a Lilliputian world, a tiny and quiet beauty that rewards close attention. Moss comes in an astounding variety of colors and forms, from delicate, chartreuse fern shapes to broccoli-green, cushiony pads.

Judith Harpel, of Brush Prairie, Clark County, curator of the bryophyte collection at the University of British Columbia, has logged 579 species of moss in Washington alone, and she's still counting.

"They are never forcing you to pay attention to them," said James Wood, a moss specialist at the Bloedel Reserve on Bainbridge Island, home to one of the largest moss gardens in North America. "They kind of glow after it has rained, and when the sun is on them, they are so bright. They have been particularly happy and lush this year, it's been really good weather for mosses to have sex.

"It's been great weather for them to grow and reproduce. They are having a great spring."

But it's been a damper for sure for some of us: Sarah Reichard, director of the University of Washington Botanic Gardens, said that, for the first time in 12 years, she has not been able to even teach some of the plants — such as serviceberry — usually covered in her plant-identification class, because they still haven't come into flower.

On the other hand, some early-flowering plants, such as forsythia, usually are all done with by now, but are still in lovely bloom in the freeze-frame of this spring.

"It should have been done flowering a month ago," Reichard said. "And there are some things like mountain laurel I don't know if I'll be able to teach this year at all."

Reichard noted the consolation prize is red flowering currant, with its blooms still lovely and full when it normally would be fading by now, a treat for hummingbirds and people alike.

Johnny Burg, a meteorologist at the National Weather Service, notes the average temperature has been about 5 degrees below normal, and Cliff Mass, atmospheric scientist at UW, confirms it's not our imagination that this spring has been a cold, wet blanket.

"It's pretty bad," Mass said. "It's an all-time record for the least number of days above 55 degrees" — for him a temperature that feels like spring.

So far, he's enjoyed only two 55-degree days since Feb. 1 — compared with 26 by now last year.

"The pattern has been unbelievably persistent," Mass said. "Cold and showery, and the mountains getting clobbered, day after day."

Andy Navage, director of horticulture at the Bloedel Reserve, is taking it all in stride. "We have some parts of the garden that got hammered by the terrible weather," he said.

"But the moss garden looks great."

Lynda V. Mapes: 206-464-2736

or lmapes@seattletimes.com