Evergreens, shrubs, and hedges took a beating this winter from ice and snow. Spring is the ideal time to practice some corrective pruning to head off those problems for the following year, according to Ed Broadbent, Section Gardener.

“When you get a heavy snow load, plants buckle, collapse, and get disfigured,” Broadbent explains. “With evergreen hedging plants especially, it is important to punch holes into plants so the snow and ice can fall through. By practicing selective depth pruning with your hedging plants, you can minimize the damage.” This is a technique by which you thin out the tops and sides of the plants by pruning back to a branch junction. It encourages interior growth on the plant, and is best undertaken in March or April. Selective depth pruning—as opposed to shearing with electric hedge clippers—allows you to hide your pruning cuts, which results in a more attractive plant.

Arborvitae (Thuja) have really suffered this year. Be on the lookout for multiple leaders in these plants. “You will have a much better arborvitae hedge with a single stem or leader,” says Broadbent. “When there are multiple leaders, the plant tends to splay apart in the snow.” Try to reduce and discourage multiple leaders in your hedge. Ideally, plant only single-leader arborvitae plants.

For early spring color, Broadbent says that wallflowers, snapdragons, and pansies (Viola) are pretty tough and will tolerate cooler temperatures. He stresses the importance of good drainage in your flowerbeds where spring bulbs will be grown each year. Tulips, foxtail-lilies (Eremurus), and alliums in particular require well-drained soils. Quamash (Camassia) and summer snowflakes (Leucojum) are examples of underused bulbs that can tolerate moister soil conditions.

Broadbent, who is responsible for Longwood’s gorgeous Flower Garden Walk, also urges people to have patience when planting. “The summer annuals that the garden centers and nurseries bring out are really enticing,” he says, “and we’re all eager to get out and start planting. It’s important to reach the frost-free date first before planting these in the garden. We generally use May 15 around here.”

How Did They Do That? Cultivating the Famed Blue Poppy

In early March, Longwood’s renowned blue poppy (Meconopsis) returns, one of the few places outside Scotland, Alaska, or the Himalayas where you can see masses of the flower in bloom. A stunning crop of Meconopsis will decorate the Exhibition Hall with their unique blue blossoms.

The process took several years to perfect. “Longwood had tried growing Meconopsis from seed, but the plants had a tough time getting through the summer,” says Jim Harbage, Research and Production Leader. “In about 2001 a Longwood graduate student discovered that when Meconopsis are exposed to temperatures above 70 degrees, they use more energy than they capture from photosynthesis and they start to die. This made sense, since Meconopsis are native to the high altitudes in the Himalayas where summers are always quite cool. It allowed us to refocus on how to grow it as a crop.”

Longwood purchases seedlings from a nursery in Alaska. The Meconopsis have had one growing season outdoors, and arrive at Longwood in mid-October. “The plants are pretty much going dormant when they’re shipped here,” Harbage says. “We cut off the foliage so they don’t get moldy, repot them, water them thoroughly, and put them in coolers at 34 degrees to simulate winter. This initiates the flower buds.” The plants are then watered every two to three weeks. “Where they occur in the Himalayas is boggy,” Harbage adds. “They have a fine root system and like to be moist.”

Around New Year’s Day, Harbage’s team moves the plants to 8-inch fiber pots and relocates them to greenhouse benches. “At this point, we’re simulating spring,” explains Harbage. “We keep the nighttime temperature at either 45 or 50 degrees, and five degrees warmer in the daytime. We’ve got it down to a pretty good system. Juergen Steininger, Horticulture Specialty Grower, is the person responsible for actually growing the Meconopsis, and thanks to him we have been able to hit our date every year.”

The seedlings don’t all come into bloom at the same time. As soon as about thirty plants are blooming, the display crew is alerted. As additional plants flower, they are installed in the display to supplement or replace the existing plants.

“They bloom for about two weeks,” says Harbage. “Each plant has one flower stalk—or rarely, two—with four or five flowers.”

The jury is still out on what causes the blooms of Meconopsis to vary in color, ranging    from the classic clear blue to more of a purple. “It could be soil pH, or a nutrient or lack of it that influences the color,” says Harbage. “We just don’t know yet.”

Harbage is amused by the amount of attention Longwood’s blue poppies receive every year. “People come through the front door and ask where the Meconopsis are. I’ve never seen as many tripods as I do when they’re in bloom.

“I love flowers and I think it’s a beautiful flower,” he adds. We’re probably the only ones doing it as a crop. It’s great fun.”

For more information about the blue poppy display and other spring events, visit http://www.longwoodgardens.org/OrchidExtravaganzaPR.html