The zinnias outside the Greencastle Post Office are real attention-getters in a riot of reds, pinks, yellows and oranges.

Standing in the elevated bed to cut off faded blooms, Marie Eshleman and Jan Hirneisen were up to their waists amid the State Fair zinnias Tuesday morning.

They were serenaded with admiring comments as they worked and even drew the attention of a Florida man on a charity bike ride from Virginia Beach to the Boston Harbor.

“I walk by every day and admire these zinnias,” said Greencastle Tax Collector Sue Myers, who was accompanied by her Boston terrier SuzyQ. “We’re so lucky to have these girls do this — our beautiful flowers in our pretty little town.”

Eshleman spearheads the plantings around town and gets help from other volunteers like Hirneisen.

“I love the flowers,” Robert Phenicie said as he walked by. “I live across the street and see them every day.”

If the giant zinnias seem especially lush and full, Eshleman reveals her secret: She mixes granules of Miracle-Gro with potting soil in the bottom of the holes before planting them.

“I think it helps give them a root start,” she said, adding, “The rains have been wonderful.”

The zinnias are deheaded so they don’t go to seed (which wastes energy) and will keep on blooming.

“It sure is pretty,” a passing driver called from Baltimore Street, waving out the window.

That was shortly before Douglas Johnston pulled his bike in front of the flowerbed.

He is participating in the Spring into Summer Bicycle Challenge for Navy retirees, who collect donations to buy bicycle helmets for needy children. Although the official ride is from Virginia to Massachusetts, he’s taking the long route — from Naples, Florida, and via Canada on U.S. 11. He’s doing the 1,800-mile plus route in increments of about 71 miles a day. His partner, John, who died of pneumonia two months ago, participated in the Spring into Summer Challenge every year and Johnston is doing this ride for him.

On Tuesday, he started in Martinsburg, West Virginia, and was aiming for Chambersburg, asking for $2 donations from those he met along the way.