We’ve reached the dog days of summer, the time when annual plants are gasping for a break from the heat and might need to be watered twice a day.

Perennial plants, however, can be hardy through the heat. In a few months, many have beautiful twigs on display or seed pods for birds. And they bloom again year after year, making them much easier to maintain.

Stephanie Cohen fills her yard in Collegeville with so many perennials, this garden writer calls herself the “Perennial Diva.” Her perennials provide color year-round and most resist the deer that roam the neighborhood. She wishes more people would plant perennials.

“If they know what they’re doing when they pick out their plants,” she says, “they can have flowers from spring through fall.”

Cohen will share her favorite new perennial plants and talk about flowering perennial shrubs at the Summer Garden Experience on Saturday, July 27, at Penn State’s Southeast Agricultural Research and Extension Center near Landisville. The center will be open for the day so visitors can learn about gardening and horticultural research and see which plants perform the best at the site’s trial gardens.

The center, one of Penn State’s four research farms, is open weekdays from dawn to dusk, June through August. Having a special event attracts more people and gives visitors access to areas that are usually off-limits, including the farm research trials of crops like hemp and barley.

The day will also have information about managing stormwater, plus tours of the site’s idea gardens and pollinator gardens. Experts will share information about topics from container gardening and turf grass to preserving herbs and planting in soggy sites. There’s also a plant sale.

Tim Abbey, extension educator, is one of the organizers and will be sharing tips on stopping the spread of the invasive pest, the spotted lanternfly.

The leaf-hopping insect was first seen in Berks County, and Lancaster County is now part of the quarantine zone. In the next few weeks, the insect will change from black nymphs with white spots to adults with black-spotted brown and red wings.

When traveling in the region, people can keep car windows closed to prevent spreading spotted lanternfly further, Abbey says.

The pest will also start laying eggs in the middle of September. Checking vehicles and patio furniture for egg masses will also help, he says.

SGE Perennial

Helleborus 'Showtime Ruffles' is a perennial flower that blooms early and usually not eaten by deer.

Forgiving plants

Abbey and the day’s organizers invited speakers like Cohen to share information for home gardeners.

Years ago, Cohen used to focus on houseplants. As her collection grew, her plants got in the way and even led to two burned-out cabinet televisions.

So she looked outside and found a new passion. Perennials are her focus. In them, she’s found forgiving plants that return year after year, often for decades.

Cohen has some long-time favorites, but she’s always trying new perennial plants. Stachys hummelo, the perennial plant of the year, is one of her new favorites. It has purple-topped spikes and is not fussy.

“It’s tough as nails,” Cohen says.

She’ll also talk about using perennial flowering shrubs in borders. They’re low-maintenance, which is great for older gardeners, Cohen says.

“Some of them, you just prune them once a year and you walk away and you forget about them,” she says. “Maybe you fertilize them in the spring and that’s it.”

Fothergilla, for example, has feathery white flowers and blue-green foliage that doesn’t fade through the summer. In fall, the leaves put on a show with reds, oranges and yellows. It’s also native to this area.

Cohen grows blueberries, not for fruit but as an ornamental hedge. They have nice flowers and she’s fond of the peach sorbet variety for the foliage that turns dark purple, almost black.

“People say, ‘What’s that?’ and I say, ‘blueberry’ and they say, ‘What’s the joke?’ ” she says. “It’s not a joke. Some of them turn the most spectacular colors, so why not think along those lines?”