Small Backyard Designs: Container Gardening in Seattle

By Janine Anderson, CPH
Professional Member, APLD

Thoughtfully designed and strategically placed container plantings can give you a big aesthetic bang for your landscaping buck. Compared with an entire garden bed, planted containers occupy relatively little space, yet they have a huge impact.

Container plantings can be focal points or help unify a garden and make it feel more intimate. They also increase your garden space if your beds have run out of room.

Although container plantings occupy relatively little space relative to garden beds, that does not mean they are simple. Container plantings can be stunning, but they sometimes appear uninspired or are poorly maintained. In addition to their composition, pitfalls relate to the type of container, soil mix, placement, irrigation, and nutrients. In other words, just like other areas of your garden, container plantings need attention.

The intent of this article is to tease you with some of the possibilities, then give you enough nuts and bolts information to enable you to create eye-catching container plantings of your own!

Design Styles
There are many types of container plantings. You might consider designing a container planting that complements the style or color of your home. This article profiles two common approaches to container design, termed here "flashy and splashy" and "restrained and understated."

Flashy and splashy. Anyone who has studied container plantings probably has encountered the term "thrillers, spillers, and fillers." It refers to the basic principle of incorporating three main elements into your composition. The "thriller" is an eye-catching focal plant that is taller and more dramatic than the rest of the composition; the "spiller" is a trailing plant that drapes over the side of the pot; the "filler" is just that—one or more plants that fill up the bulk of the container.

Following this principle generally yields good results, assuming thought is given to how the different elements complement one another. It is especially useful for warmer-season plantings, when more time is spent outdoors and you can fully appreciate the drama of these over-the-top compositions. Also, annual plants are often used in these plantings, and annuals are not hardy year-round.

Brilliantly colored foliage pops in part shade. Plantings include Digiplexis, fuchsia, begonias, and sweet potato vine. Design by Kristy Law; photo courtesy of Richard Law

Glass art spires rise above plants in this cluster of containers, which include Chamaecyparis ‘Nana lutea’, Canna ‘Dark Knight’, nasturtium, zonal geranium ‘Mrs. Pollock’, and pink calibrachoa. Design and photo by Kryssie Maybay

Restrained and understated. Though not necessarily at the opposite end of the style spectrum, elegant and restrained container plantings tend less toward splashy and more toward refined, which does not mean they can’t be awe inspiring. The awe they inspire tends to be more quiet than loud, while still having a profound impact. The color range tends to be narrower than found in splashy summer offerings, and foliage color and texture dominate over flower power.

A restrained color palette provides the "wow" factor in this elegant composition. Bronzy tone of large steel planter is reflected in Canna ‘Cannova Bronze Scarlet’; bluish tones are found in palm (Butia capitata), groundcover sedums, Dichondra 'Silver Falls', Eryngium agavifolium, and Blue Chalk Stick succulent; bright greens include Ipomoea batatas var. margarita and Abutilon. Design and photo by Lisa Bauer

White fiberglass pot is a focal point by itself, with Acer palmatum 'Fairy Lights', Setcreasea 'Purple Heart', and white Salvia splendens. Design and photo by Lisa Bauer

Containers featuring dramatically varying foliage, including Schefflera delavayi, Magnolia officinalis ‘Biloba’, and Hesperaloe funifera, line the entry courtyard to this modern home. The large rustic vessel on the far right contains Agapanthus ‘Blue Leap’, which stands 6 feet tall, blooms summer to fall, and is intoxicating to hummingbirds. Design by North Beach Landscapes; photo © Doreen Wynja

Visitors are greeted by simple and restrained container plantings flanking entry gate. Gray fiber cement pots hide spigot and irrigation controls. Species rhododendrons, Brunnera ‘Jack Frost’, Japanese forest grass, and Dryopteris affinis ’Cristata the King’ are among the container plants used along the house’s north face. Design by North Beach Landscapes; photo © Doreen Wynja

Resources and Practical Considerations
Container gardening has become hugely popular, and garden centers have responded by providing everything you might need, including ideas, to build your own creations. Wells Medina, Swanson’s, and Molbak’s are among the Seattle-area nurseries that provide examples of plantings you can mimic in your own landscape. They create stunning compositions, then provide lists of the plants, and of course you can buy everything you need right there, making it as easy as it can be. More information can be found in handouts and on-line resources.

Nurseries are a great resource for gardeners. Taking a picture of this container display planting and the accompanying plant list at Wells Medina Nursery will enable you to recreate it. Photo courtesy of North Beach Landscapes

Pots. As container gardening has increased in popularity, so too have the variety of pots available. They are available in many sizes and colors. Different sizes of the same pot are striking when grouped together.

High-fired, frost-proof clay pots from Vietnam have been popular for decades, and deservedly so. There are rustic (unglazed) forms as well as glazed pots in neutral and eye-popping colors. Colorful pots help brighten shady areas. A downside of these pots is their weight. They are often very heavy and hard to move, especially after soil and plants are added. Also, weight load should be considered if placed on a deck.

Plantings in a pair of rustic Vietnamese pots at the corner of a patio include ‘Kanga Yellow’ kangaroo paws with Sedum pluricaule 'Isle of Sakhalin', Sorbaria sorbifolia ‘Sem’, and heucheras. Photo and design by North Beach Landscapes

Depending on its shape, a terra cotta vessel can seem either formal or casual. Fiber cement pots are light weight so are easy to move, even after plants and soil have been added. Plantings really pop in dark-toned (e.g., charcoal or black) fiber cement pots. Corten and galvanized powder-coated steel planters look sleek and modern.

Pots come in many different shapes. Your job will be easiest, however, if you select simple shapes that are widest at the top. When a pot tapers toward the top, it can be difficult to remove rooted plants should you want to redo your planting.

Plants. Now is not the time to be timid! To have the greatest impact, you need to be bold. There are very few plants that can’t be contained given the right-sized pot and proper care. Conifers vary widely in texture, form, color, and scale and can make fun thrillers or fillers in your composition. Refer to previous articles on conifers and shrubs for small gardens for ideas of what you might use. The Great Plant Picks website has an extensive list of plants suitable for containers.

Shrubs that are effective in containers include Abelia, heather (Calluna vulgaris), Ceanothus, fuchsias, hebes, Osmanthus heterophyllus ‘Goshiki’, Physocarpus (Ninebark), rosemary, and Phlomis (Jerusalem sage). To heighten the drama, try Acacia pravissima (Oven’s Wattle), Acanthus (bear’s breeches), Acer palmatum, Italian cypress, Dasylirion wheeleri (a yucca-like desert plant),Fatsia japonica, Magnolia grandiflora, and Melianthus major. For smaller fillers and spillers, consider sweet flag (Acorus gramineus), Coleus, Agapanthus,Euphorbia, Fatshedera, blue fescue,Gaura lindheimeri, hellebores, Japanese forest grass (Hakonechloa macra), variegated Algerian ivy, blue oat grass, Heuchera, sweet potato vine (Ipomoea batatas), black mondo grass, groundcover and cascading oreganos, zonal geraniums, digger’s speedwell (Parahebe perfoliata), upright and groundcover sages, and large and small sedums.

If possible, include a plant of interest for each season. In winter, add cut branches of colorful twig dogwood or dried stalks of allium. Some aggressive plants, such as wire vine and English ivy, are attractive in pots but can create problems for other plants. Try to avoid combining plants that have widely varying cultural needs, such as for sun and water.

Soil, food, and water. Use a commercial potting soil such as Cedar Grove or Whitney Farms. Avoid mixes with vermiculite, which can cause asthma and allergies, and perlite, which rises to the top. Apply Sluggo if slugs or snails are a problem. For year-round plantings, use an organic fertilizer such as Whitney Farms 5-5-5. Apply heat-activated Osmocote at planting for fast growth of summer annuals and perennials; then add diluted Miracle Grow or Rapid Gro every seven to ten days. Follow the package instructions for all products.

When planting, it is advisable to fill the pot with soil, then water thoroughly before planting. This helps the soil settle and eliminates air pockets. Staining is almost inevitable if the pot is placed on a patio or deck, but scrubbing the stained area with a mild soap such as Dr. Bronner’s castile soap can remove most or all of the stain. Use pot feet if the pot is placed directly on the soil, and don’t cover the drainage hole with shards or rocks. In fact, if your pot has only one drainage hole, you might want to drill several more that are at least ¾" in diameter. You want to avoid water sitting at the bottom of the pot.

Don’t forget to water! When watering by hand, wait until water runs out of the bottom of the pot so that you know the container is thoroughly irrigated. Water again when the top few inches of the soil seem dry. You can also install a low-volume irrigation system by threading the irrigation tubing through the bottom drainage hole and bringing it up to soil level. Regardless of the technique, be sure the root systems of all the plants receive water.

Final Thoughts

Don’t expect every container planting you create to be worthy of the grand prize in an international competition. Similar to most endeavors, trial and error are involved. In the meantime, enjoy the creative process of trying to put together a composition that pleases you. Professional landscape designers have a lot of experience creating container plantings, so don’t hesitate to contact one if you feel stuck or are reluctant to strike out on your own.