There are certain perennials you will want to think twice about before committing them to the ground in your garden. Perennial flowers often serve as the backbone of ornamental gardens. With their dependable blooms and lasting seasonal beauty, many perennial plants are ideal for creating attractive, low-maintenance landscapes.
Selecting perennials requires some thought and consideration. This includes accounting for several unique characteristics of each species, such as their growth habit, toxicity, continued care, and more. Though far from an exhaustive list, this article explores several perennial flowers to avoid as well as those that may need to be planted with caution.
Which Perennials Do I Need to Think Twice About?
When planning a garden, there are a variety of factors to consider. While a plant’s cultural needs, height at maturity, and growth habit all play a role in its overall health, you may need to consider some other characteristics. Perennials to think twice about most often include those that spread aggressively, are toxic, or are especially difficult to grow.
Perennials that are Unruly or Invasive
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- Butterfly Bush – Though considered an attractive source of nectar for most pollinators, butterfly bush is an invasive perennial. The mature shrubs will reseed aggressively, causing it to quickly invade surrounding beds. The butterfly bush’s ability to outcompete native species often results in a loss of habit and native food sources.
- English Ivy – English ivy spreads quickly. Once established, these vines rapidly overtake fields and structures. An especially vigorous climber, English ivy can scale trees and shrubs, and is able to smother out almost any landscape or natural habitat.
- Japanese Honeysuckle – Japanese honeysuckle can be found throughout much of the United States along roadsides, in ditches, and near abandoned homesites. These plants reseed aggressively and can also spread by the production of “runners,” which sprawl across the ground and root easily. Established plants are able to quickly overtake native species, resulting in severe damage to local ecosystems.
Perennials that are Toxic or Dangerous
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- Lily of the Valley – Lily of the valley plants are often praised for their beauty and use a spring-flowering groundcover. However, all parts of the plant contain compounds known as convallatoxin and convalloside – making them highly toxic. Results of accidental ingestion of these plants include slowed heartbeat, collapse, as well as death.
- Monkshood – Gardeners are often drawn to monkshood for their alluring blue-purple flower tones. Most are surprised to find that the plant is among the most poisonous in the garden, containing aconitine. Aconitine is especially worrisome, as simply touching the plant can expose you to the compound. Extreme caution should be used by anyone choosing to grow monkshood.
- Oleander – Though somewhat common in southern gardens, oleander plants should be grown only with proper care. These plants contain oleandrin, a compound that directly affects the vascular system and heart, potentially leading to death. Experts encourage correct handling to prevent exposure, which includes using gloves to prevent contact with skin.
Perennials that are Hard Work in Small Yards
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- Bamboo – Similar to other invasive species, bamboo is often introduced into the landscape as an ornamental. Robust plants grow easily, but require constant maintenance to prevent their escape into neighboring flower beds or even neighboring yards. To keep work light, plant bamboo only in pots or containers.
- Mint – The benefits of fresh mint are numerous. However, containing the plant to a small space can be quite difficult. Like bamboo, the hardest part of growing mint is working to control it. Fortunately, your workload can be lightened greatly by planting mint in containers or sinking their pots into the ground to manage root growth and spread.
- Wisteria – Each spring, established wisteria plants produce masses of elegant, draping flowers. Vines are considered easy to grow and thrive under a wide range of conditions. Still, some may want to rethink the plant, due the amount of work involved in its care. This includes the prevention of its spread, as well as deadheading and seasonal pruning.
Perennials that are Tricky to Grow
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- Azalea – Azaleas are praised for their impactful, early-season floral displays. However, this plant can be difficult to grow where conditions are less than ideal. Choose a planting site that is slightly acidic and receives ample indirect light throughout the day.
- Gardenia – Highly fragrant, gardenias make a stunning addition to the home landscape. Gardenias require consistent temperatures to thrive, making them especially sensitive to sudden changes. The same can also be said for those grown indoors in containers. For the best results, position your houseplants safely away from drafts or vents.
- Orchid – Orchids are often recognized as among the most tricky perennials to grow. This usually relates directly to their specific needs for growth and inability to rebloom unless conditions are met. Still, if you hope to grow orchids at home you should not be discouraged, as proper care will often result in consistently beautiful potted specimens.
Frequently Asked Questions
Which Perennials Should Not Be Planted Together?
At planting time consider the growth habit and overall size of plants at maturity. It’s best to avoid planting species that are aggressive or behave invasively, especially among native plants. This can also be said of plants that grow to be especially tall or might shade-out other species.
What are the Hardest Perennials to Grow?
Most gardeners find that the hardest perennials to grow are those whose requirements for growth can not be met within their space. Fortunately, cultivating these plants indoors is often a viable option. Other hard-to-grow plants include those with poor germination rates or that are especially difficult to start from seed.
Which Perennials Self-Seed Too Quickly?
A large number of perennial species will reseed quickly. This often leads them to overpopulate flower beds, escape cultivation, and become invasive. Researching each garden introduction, before planting, will help growers to determine whether or not new plants may be a potential threat to their growing space.
