8 Container Gardening Mistakes To Avoid (Plus 5 Solutions!), According To Experts

No matter if you’re a gardening novice or avid planter, we all make mistakes whether it’s neglecting our blooms while away on vacation or accidentally overwatering them. While flower beds and shrubs can be a bit more forgiving, container gardening takes a little more attention. We called on two plant pros to share container gardening mistakes that should be avoided, along with easy solutions to combat them.

Not Ensuring Good Drainage

From over-watering to under-watering, properly hydrating your plants is just as important as ensuring your pots have drainage. “Good drainage is essential when growing plants in containers,” says McConnell. “Water-logging can cause root rot in plants, particularly varieties that are sensitive to overwatering. This can harm the plant's long-term health or even kill it.”

Poor drainage can also lead to a variety of issues from pests to diseases. “Unfortunately, simply adding gravel or large rocks to the bottom of your container planting isn’t enough if your container doesn’t have any drainage holes; it will only raise the water table in your container.”

The Solution:

“Ensure that your container has drainage holes and that you’re using a soil blend appropriate for the water needs of the varieties you’re growing in it,” says McConnell.

Using The Wrong Soil

Making sure your soil has all the right elements is essential to healthy blooms no matter where they are planted, but container-grown plants have specific soil needs compared to those planted in the ground that receive natural nutrients from the earth.

“For popular container-grown plants such as hydrangeas, gardenias, and azaleas, choose well-draining soil that facilitates adequate airflow, moisture retention, and nutrition,” explains McConnell. “Soil taken directly from your yard or bags labeled ‘garden soi’ at the store is not generally ideal for containers; it is often too dense and heavy to allow for adequate root growth and drainage.”

The Solution:

“Look for a potting mix with ingredients like peat moss, pearlite, and pine bark,” suggests McConnell. “You may also want to look for mixes that contain fertilizer to support your plants’ growth.”

Planting All The Same Height 

Rather than just plopping a few ho-hum containers scattered around your outdoor spaces that all look the same, use varying heights to help add interest. This applies not only to the contents within, but also the vessels themselves. “Choosing a shrub or staked vine to anchor the container and move from season to season is a great way to balance smaller seasonal annuals,” says Tamony. 

Forgetting To Consider Weather Sensitivity

It’s important not only to consider where your containers are going to live before selecting the elements within them, as some require more shade or sun than others to thrive, but also the general weather conditions they are likely to endure. “When plants are grown in containers, their roots are less protected by the ambient temperature of the earth than they would be if they were grown in-ground,” says McConnell.

Those in pots are more susceptible to cold damage, which can lead to slower growth or foliage and bud loss. “Since containers offer a more limited volume of soil with which to insulate their sensitive roots, the roots are more exposed to the surrounding air and its fluctuating temperatures.” The same applies to containers exposed to high temperatures and excessive sunlight as they cannot hold as much moisture making your plants become dehydrated faster.

The Solution:

• “If you would like to keep your container plants outdoors all winter, the easiest option is to select plants that are hardy one to two USDA Zones colder than your area,” says McConnell. “For instance, if you live in Zone 7a, you’ll want to select container plants that are cold hardy to Zone 6a or 5a.”
• “Another solution is to move your container plants to a cool indoor space during the winter, like a garage or an interior room with a sunny window. If you’re moving the plant to a garage, ensure that it continues to receive some sunlight and ensure that the indoor temperature doesn’t consistently fall below the cold range of your plant’s hardiness zone," adds McConnell.

Sticking To The Thriller, Filler, Spiller Formula

This classic approach to container design is a tried-and-true method, but it doesn’t mean it's the only way to filling and arranging your pots. “This three plant design strategy is timeless, but mono plant containers and larger containers with more than three plant types can be stunning and unexpected,” says Tamony. You can even try something new and less-expected like a topiary or edible perennials. “Using a topiary in a container creates an instant statement piece and planting blueberries with beautiful foliage such as Bountiful™ Baby Blueberry, compact blackberries, or even herbs can capture attention. It also offers easy access for harvesting,” she says.

Pairing The Wrong Plants Together

While you might be tempted to just throw whatever looks pretty together in a pot, that might not be your best recipe for success. Instead, combine plants with similar requirements. “Plants are like people and not every ‘roommate’ gets along,” says McConnell. “When selecting plants to live in the same container, it’s essential to consider the sunlight, zone hardiness, soil needs, and water requirements of each plant.” Avoid putting shade-loving plants alongside sun-loving varieties that need six or more hours of direct sunlight a day.

The Solution:

• “If you’re looking to create your own unique combination, refer to the plant information tag that comes with your plant when you purchase it at the store. Check its sun and shade tolerance, USDA Zone hardiness, soil needs, and watering requirements,” says McConnell. “Pair plants whose needs are compatible so that you can situate and care for your container in a manner that ensures its success.”
• McConnell suggests this container combination recipe for success in a sunny spaces: Design-A-Line™ Cordyline, ‘Sunshine’ Ligustrum, Saucy Wine™ Salvia, and Purple Pixie® Dwarf Weeping Loropetalum.

Using Roses Solely As Landscape Plants

Though commonly used for climbing trellises, filling garden beds, and lining fences, roses aren’t just for planting in the ground. They also make a beautiful and hardy container filler suited to a variety of sunny and shady spaces. “Compact roses such as Monrovia’s Nitty Gritty™ Rose collection provide season-long, easy-care color in containers and spill nicely over the rims,” says Tamony. “With five colors to choose from, you’re sure to find a favorite.”

Only Using Annuals In Your Containers

“If you’re looking for colorful, eye-catching planters, you don’t have to rely on annuals alone to get the look,” explains McConnell. “Annuals are an attractive filler for containers, but their beauty often only lasts a few months, then they fade or succumb to the season’s temperatures.” Sticking to one-and-done blooms can be more costly and cause added work as you’re constantly replanting.

“Perennials and compact shrubs are an excellent way to anchor containers,” adds Tamony. “Compact hydrangea, Hosta, canna, roses, echinacea, and even smaller conifers can add structure and texture as well as color.” 

The Solution:

• Anchor your containers with shrubs and perennials. “A compact or dwarf variety shrub can provide multiple seasons of beauty and then it can even be transplanted into your yard after its ‘service’ in your planter is done,” says McConnell. “Container-friendly varieties of woody shrubs can thrive in planters for years, resulting in less labor and money spent in the long run. Another bonus of creating containers with shrubs and perennials is that you can get the bountiful blooms, pollinator interest, and enchanting fragrance that annuals would provide, but with better longevity and long-term value.”
• A few varieties McConnell suggests include evergreen shrubs like Golden Oakland® Holly and Purple Pixie® Dwarf Weeping Loropetalum for four seasons of color, Diamond Spire® Gardenia for compact blooms and fragrance, and perennials like ‘Soft Caress’ Mahonia and ‘Pink Fizz’ Heucherella for shady spaces.