Container Gardening

Perhaps it's time to retire the notion that container gardens start with red geraniums, that a dracaena spike adds drama and that sweet alyssum pulls a composition together. Such a palette may be fine for those who cherish tradition, but many of us are so ready to move on.

The only rule for contemporary container gardens is that there are no rules. Virtually anything goes: annuals, perennials, shrubs, trees, ornamental grasses, roses, ferns, herbs, tropical plants, cacti, vegetables and bulbs. If it has roots and will fit in a pot, it’s fair game for container-gardening enthusiasts.

As the examples on these pages demonstrate, the region’s gardeners are embracing this “no holds barred” approach to growing above ground. A horticultural sneak peek into Pittsburgh’s back yards uncovered sumptuous succulents in Mount Lebanon, bold bananas in Beaver, tremendous troughs in Wexford and fabulous foliage in Fox Chapel. I did spot a fancy dracaena spike or two but not a single red geranium. And the only sweet alyssum was an outstanding new variety called ‘Snow Princess,’ which elegantly updates this old-fashioned annual.

The Basics
While end results may vary dramatically, the three building blocks of beautiful containers remain constant: Plants, pots and soil must work in tandem. Horticultural experts generally suggest starting from the ground up.

The Soil
Begin with a peat-based (soilless) potting mix formulated for containers. There are several brands, but I prefer one with ground up hardwood bark as one of the ingredients. The bark helps improve drainage. Use “as is,” or add special amendments if you like. My standard recipe includes:

3 parts commercial peat-based potting mix
1 part dehydrated cow manure
1 part bagged (weed free) topsoil
1- 2 tablespoons Osmocote slow-release fertilizer per large container

For succulents, herbs and other plants that need sharp drainage, I add one part coarse perlite to the mix.

I used to add water-absorbing polymer crystals to each batch of mix, but no longer. The products I tried didn’t seem to reduce the frequency of watering, and the surface of the soil stayed too moist for some plants, causing stems to rot.

If synthetic plant foods, such as Osmocote, Miracle Grow and Peters Soluble Fertilizer, don’t suit your gardening style, there are plenty of organic products available. Bloodmeal, cottonseed meal, Espoma products and Posy Power are a few that derive their nutrients from natural ingredients. Use fertilizers higher in phosphorus for flowering plants and higher in nitrogen for foliage plants. Some gardeners rely solely on the balanced nutrition found in homemade compost to feed their container plants.

The Pots
Almost any vessel that will hold soil and water can serve as a container. An old boot may live out its life filled with hens-and-chicks on the back step. Fruit crates lined with plastic, old wheelbarrows tipped on end and truck tires painted white enliven landscapes along Pennsylvania’s country roads. But for timeless beauty, there are more permanent choices for front door, patio and pool.

Select containers based on personal taste, appropriateness for the site and expectations. Size them accordingly—a small pot in a vast space looks puny, even if it’s extravagantly planted.

Denise Lindberg, owner of Gardener’s Eye, specializes in container gardens and carries pots of all types for gardeners and designers in her Allison Park shop. Her company also plants and maintains container gardens for a host of commercial and residential customers all over Pittsburgh.

In Denise’s experience, the most reliable winter-proof containers are made of metal. Copper, zinc and aluminum pots come in both contemporary and traditional styles and will last for years outdoors in all seasons.

Cast stone planters exhibit the warmth and beauty of natural stone, but they’re variable with respect to winter-worthiness. Heavier pots have a greater chance of withstanding the relentless forces of freezing and thawing.

Some manufacturers suggest emptying cast stone planters for winter to mitigate the damage caused when the soil expands.
Planters made of resins, plastics and fiberglass offer gardeners an extraordinary range of styles, colors and prices. Some are very lightweight yet so closely imitate real stone that it’s hard to spot the “fakes”.

Many of these synthetic materials withstand winter weather quite well. They look marvelous for the holidays—and afterward—filled with seasonal arrangements of evergreen boughs, branches, berries, pods and pinecones.

Always bring ceramic and terra cotta (even the sturdy, thick-walled Italian terra cotta) pots indoors for the winter. Dry storage will extend the life of concrete planters as well.

The Plants
Blooming annuals used to be the “go-to” plants for containers. They’re still a popular and reliable source of color, but foliage is quickly catching up. Just look at the scrumptious varieties of coleus vying for bench space with impatiens and begonias at local greenhouses!

With big, bold leaves and carnival colors, tropical plants easily out-perform dracaena spikes in the drama department. Ornamental grasses, especially those with dark red leaves and saucy plumes, are big on texture and good for contrast with those high, wide and handsome foliage plants.

Hardy perennials were once dismissed as having too brief a bloom period to be effective as pot plants. But they’re coming on strong, winning fans among the horticultural cognoscenti. 

Perennial Wand Flower was among the first to be widely accepted when new long-blooming varieties appeared. Tucked among the annuals and marketed as container plants, gardeners were none the wiser but loved them for their wispy blooms and brand-new look. Then came a wave of coralbells with foliage so stunning that the flowers were accessory rather than essential.

Ajuga, thyme, lamium, Japanese forest grass, yucca, creeping Jenny and hardy ivies are other perennials with a lot to offer foliage fanatics.

Perennials usually command a higher price than annuals, but if you’re willing to dig them up and put them into an outdoor holding bed for the winter, they can be re-used.

Hardy bulbs, such as tulips and hyacinths, will likely always present a temptation, but I’d urge gardeners in our climate zone to resist. Take it from one who has loved and lost: they’ll freeze (to death) in above-ground containers. If you crave the show that only tulips can satisfy, sink pots of purchased or forced bulbs into outdoor containers in spring.

Shrubs and small trees require more of a commitment than other types of container plants, but an increasing number of gardeners are willing to make the investment. Japanese maples adapt well to pot culture and offer gardeners a wide variety of sizes, shapes and foliage colors.

Protect the roots of these and other hardy trees and shrubs from killing temperatures by moving the pots into a cold garage after the leaves have fallen. Be sure to water them well before tucking them in for the winter.

Maintenance
If container gardens came with “care tags,” the instructions would read:

• Pay a little bit of attention, all the time.
• Pinch off dead flowers and faded leaves frequently, and grooming will never become a chore.
• Fertilize liberally and often—remember, the roots are working hard in a confined space.
• Water often, but not too often; let pots dry out a little bit between soakings.
• No weeding required.

John and Lindsay Totten garden on their small family farm in Cheswick. Lindsay is the former president of the Botanic Garden of Western Pennsylvania and now is the director of development and communications for Three Rivers Adoption Council, Inc. John is a professional horticulturist with a small landscape gardening business; he also teaches a class on native plants in the landscape architecture program at Chatham University.

Tips for gardeners

Advice from the experts whose creative combinations are featured here will help you coax maximum pizzazz from your pots.

Deadhead your plants [remove spent blossoms] often; they’ll bloom longer. And to keep pots from fading while you’re away on vacation, deadhead everything thoroughly before you go—even take the flower buds off—and move the pots into the shade. They’ll be in full bloom by the time you get back.
– Betty Anderson (Mars)

Choose one nice big pot over several smaller pots, and stuff it full for maximum impact. The greater soil volume holds more moisture, making larger pots easier to maintain than small ones.
– Judy and Joyce Lonnett (Beaver)

Match sun and shade varieties carefully to existing conditions. If the two are mixed in the same pot, something is likely to die.
– Connie James (Wexford)

Focus on foliage rather than flowers, and pots will stay lovely through October. Good foliage plants also save work and money. They don’t have to be switched out as often as blooming plants do, and they don’t have to be deadheaded as often.
– Denise Lindberg (Allison Park)

Pay careful attention to drainage. Succulents benefit from the addition of coir [shredded coconut husk fiber] and bonemeal to their potting mix. Both products are available at garden centers. Also, elevate pots above their saucers on little “pot feet” to speed drainage.
– Sheila Nathanson (Mount Lebanon)

Shrubs and trees are actually less work than annuals, even taking into account the chore of over-wintering them. They’re easier on the budget, too; you can derive years of enjoyment from a single planting. And if one gets too big for its pot, move it to the garden!
– Cory Polena (Mount Lebanon)