6 Perennial Flowers to Never Plant in Your Yard

A cluster of Japanese honeysuckle flowers in bloom with green leaves and a blue sky in the background — Credit:
Getty Images

Perennial flowers are the heroes of the garden, returning every year bigger and better than they were the previous season. But it's important to be careful when choosing which varieties to plant in your landscape, as some are more trouble than all the beauty they provide. From invasive species to blooms with toxic compounds, these are the six perennial flowers our gardening experts warn against.

Linda Langelo, horticulture specialist at Colorado State University and author of Plants Are Speaking. Are You Listening?
Kelly Funk, president and CEO of Jackson & Perkins

01 of 06

Yellow Loosestrife

Yellow loosestrife (Lysimachia puntata) is an aggressive plant that spreads quickly by rhizomes and seed. "It outcompetes native vegetation, hurting our local ecosystem," says Linda Langelo, horticulture specialist at Colorado State University. "It reduces biodiversity by choking out the other vegetation. Although this mainly happens in wetlands, it can also happen in yards in moist areas."

02 of 06

Snow on the Mountain

Euphorbia marginata in greenhouse — Oleg1824i / Getty Images

Snow on the mountain (Euphorbia marginata) is aptly named for its white-and-green foliage and petal-like white bracts, giving it a snow-dusted appearance. Although it is a beautiful addition to the landscape, it's best to avoid planting it if you have children or pets. "It contains a toxic, milky white sap when any part of the plant is broken off," says Langelo. "It is important to wear gloves and eye protection before handling this plant." She adds that Euphorbia is self-seeding and can quickly get out of hand.

03 of 06

Common Privet

Common privet (Ligustrum vulgare) may be a beautiful perennial flowering hedge, but it is invasive in certain areas of the U.S. "It is invasive and crowds out native plants," says Langelo. "Unfortunately, birds eat the seeds and spread them prolifically." It's less aggressive in western climates where conditions are dry, but it will naturalize if planted near a waterway.

Lily of the Valley

There are a few reasons not to grow lily of the valley (Convallaria majalis) in your garden. "Lily of the valley spreads by aggressive rhizomes, is toxic to pets and children, and can dominate garden beds," says Kelly Funk, president and CEO of Jackson & Perkins. Instead, she recommends growing Dicentra 'Alba' for a similar look. "These long-lasting, small white blooms attract hummingbirds and brighten up the shady spot in your garden, where they thrive," Funk notes.

05 of 06

Bishop's Weed

If the name isn't enough to deter you, Langelo warns that bishop's weed (Aegopodium podagraria) is an extremely aggressive grower that is challenging to eradicate. "With its aggressive rhizomatic roots, this plant compacts surface soil and limits soil contact for native seeds," she says, adding that it's also harmful to birds and other animals if ingested.

06 of 06

Japanese Honeysuckle

Japanese honeysuckle (Lonicera japonica) is a vigorous vine that smothers other plants and trees, making it unsuitable for most landscapes. "A better honeysuckle selection is the 'Major Wheeler,'" says Funk. "This variety has beautiful red, trumpet-shaped flowers that attract hummingbirds and, most importantly, is not invasive."

6 Perennials That Can Become a Backyard Nightmare, Experts Warn