Borage

Who doesn't love the charming star-shaped blossoms of borage? But be careful not to deadhead plants in the Borago genus. "This family blooms with an indeterminate blooming pattern," says Soule. "This means that as long as they have nutrients and water, they will continue to bloom. New flowers will keep appearing at the end of an ever-lengthening flower stalk." She cautions that if you choose to deadhead, you'll lose this flowering stalk, meaning the plant will simply cease to bloom and not extend a new stalk.

Trailing Petunia

If you want an abundant display of blooms, trailing petunia (Calibrachoa) never disappoints. Even more exciting, those prolific blooms don't require deadheading because they are "self-cleaning" plants. That means the plant naturally sheds its spent flowers without being deadheaded.

Supertunia Petunia

If you've ever spent time deadheading a petunia plant (Petunia spp.), you know it's a time-consuming process thanks to the prolific blooming habit of this species. Supertunia plants are a self-cleaning petunia hybrid, so they stay tidy and continue blooming without deadheading.

Jerusalem Sage

Jerusalem sage (Phlomis fruticosa) is known for its vibrant yellow flowers that you won't want to deadhead. "Some members of the sage family have indeterminate flowering," says Soule. "The ones with the clusters of blooms like Jerusalem sage will just keep flowering in new clusters and growing that flowering stalk longer. If you deadhead the flowering stalk, they will cease to flower."

Lion's Tail

Lion's tail (Leonotis leonurus) is another type of indeterminate sage that shouldn't be deadheaded. If you trim the spiky orange flowers on a lion's tail plant, it will prevent the plant from making new flowers, says Soule. Instead, trim back the entire plant at the end of the season after flowering has ended.

Chia

The tiny blue flowers of chia (Salvia columbaraie) may be small, but they're hugely popular with bees. Unlike some of the other salvia species that you should deadhead, chia should not be deadheaded or it will stop flowering, says Soule.

Stonecrop

One of your classical late-blooming perennials, stonecrop (Sedum) quietly steals the show in the fall with its finely-formed blossoms. The plant maintains its form even into winter, so forgo the deadheading and allow stonecrop to bring much-needed winter interest to the garden.