5 Popular Plants I Would Never Include in a Garden

As a sustainable landscape designer who works closely with natural systems, I’ve seen firsthand how a few seemingly innocent plant choices can quietly wreak havoc over time. Many of the worst offenders are still sold widely at nurseries and big-box stores even though they're plants you should never include in a sustainable garden. They might seem low-maintenance or flashy in bloom, but they often do more harm than good, both ecologically and aesthetically.

Here are five plants I would never include in a garden I design,

and why you might want to leave them off your list too.

1. Euphorbia (Spurge)

A dangerous plant in disguise...

Most varieties of euphorbia release a toxic milky sap that can cause severe skin and eye irritation. I’ve known gardeners who ended up with chemical burns just from cutting back this plant without gloves on. Their milky sap is also highly toxic to humans and animals, making this plant a significant threat to children and animals. Beyond that, euphorbias can spread aggressively and crowd out gentler plants. They offer low ecological value, which means they offer little support to pollinators or birds.

Try instead: Woolly sunflower, shrubby cinquefoil or a species of coreopsis.

2. Spanish Bluebells (Hyacinthoides hispanica)

The bully of the spring bulb world.

These might appear as a dreamy springtime delight, but Spanish bluebells are stealthy invaders. Their clustering growth habit pushes out more delicate spring ephemerals and poses a threat to native bulbs and wildflowers. Their thick foliage and deep underground bulbs make them difficult to eradicate once they’re in the soil and they seem to pop up everywhere once they’ve bloomed just once. Try instead: Camas, nodding onion, crocus, or the less aggressive hyacinth (Hyacinthus orientalis)

3. Arborvitae (Thuja spp.)

The privacy hedge that takes more than it gives.

Arborvitae is a go-to plant for privacy hedges, especially in urban landscapes, but ecologically, they’re pitfalls. They require an immense amount of water to stay green, especially in our dry summers, making them a completely unsustainable hedge. Worse, they’re highly flammable, making them a dangerous choice in an era of increasing wildfire risk. Along with being unsustainable and highly flammable, they offer little to no food or shelter for native insects, birds, or mammals. Their dense growth also casts deep shade that prevents underplanting, and they often become leggy and unkempt with age. In gardens where resilience, biodiversity, and beauty matter, arborvitae falls flat.

Try instead: Portuguese laurel, yew, evergreen huckleberry, or even trained espaliered fruit trees for functional privacy.

4. Butterfly Bush (Buddleja davidii)

Not the pollinator hero it's made out to be.

While butterfly bush does attract adult butterflies, it offers no food for their larvae making it more of a pollinator trap than a true host plant. It’s also invasive in many regions, including coastal BC, where it escapes gardens and displaces native shrubs. Even worse, it spreads aggressively and often requires frequent pruning to keep it from taking over.

Try instead: Red-flowering currant, lilac, chokeberry or mock orange.

5. Periwinkle (Vinca major & minor)

Ground cover gone wild.

Don’t be fooled by periwinkle's demure flowers and dainty name because this plant is a bully in the garden. Once established, it forms a dense mat that chokes out native groundcovers, bulbs, and woodland wildflowers. It can easily take over a garden under the right conditions and can escape into nearby natural areas. Its borderline invasive, especially in temperate forest ecosystems like ours on the West Coast.

Worse, it’s almost impossible to remove once it's settled in and likes to hide in the roots and stems of other plants, making it a stealthy spreader.

Try instead: Wood sorrel, wild ginger or barrenwort.