On Thursday, the dark red, green and black berries glistened in the sun on the Turkey Hill Lane farm where Barnhardt also grows corn, green peppers, tomatoes and potatoes.
Currently, the canes are draped against each other, covering the narrow pathways between the rows.
"It's a jungle in here," Barnhardt said. "A pretty jungle, though."
The small farm is her world, and tending it is job she takes a lot of pride in.
Barnhardt used to sell the blackberries out of the back of her vehicle, but these days she lets customers call her and she has someone pick the fruit for her.
"Up until two years ago, I had no one to help me pick," she said.
The canes on the blackberry plants are fairly fragile, Barnhardt said, which is why she doesn't let people pick their own berries. It usually takes a plant one year to start producing fruit, she said.
Barnhardt and her family started planting the blackberry plants in the late 1980s. She said it was because her mother wanted to make jam out of the berries.
She continued to grow the berries and the patch after her mother passed away. She said they started out with a single row, and now have half an acre.
In order to grow the patch, Barnhardt takes cuttings from the older bushes and plants them.
"The old fashioned way is always the best," she said.
She said the blackberries are usually sold out by 1 p.m. or 2 p.m.
Barnhardt expects more of the berries to ripen and grow fatter as the summer progresses. Later this summer, she said, some of them will be so big that she won't be able to fit more than three or four in her hand at a time.
"I've got some customers who have been coming for 15 years," she said. "It's just good eating."
Anyone wishing to purchase berries from Barnhardt can call her at (704) 546-3339.