“There are no gardening mistakes, only experiments.” ”

Janet Kilburn Phillips

Dazzling colors, enchanting textures and edibles can all be grown in containers (pots). Containers can provide “color accents and structure in the landscape or on a terrace; a way to break up a wall, mark an entrance or create a focal accent; an ideal spot for frost-sensitive plants or those requiring special conditions to thrive; a space to confine invasive plants so they can’t spread throughout the garden; and a creative platform to experiment with companion plantings and groupings.” (Kathy Wolfe, WSU Master Gardener). 

Planning 

Julia Cordz, Jefferson County Master Gardener, suggests gardeners first consider where they will place containers and then choose plants which will thrive in those conditions. Gardeners should ask themselves: is the placement area full sun or shade, part sun or light shade, subject to wind, rain or cold with a water source close by? 

A container can be almost anything that will hold soil and has holes for drainage. Kathy Wolfe, WSU master gardener, advises selecting a pot of at least 12” in diameter for flowering annuals and perennials. Smaller pots will tend to dry out quickly and offer limited space for roots to grow. Beyond common plant containers of terracotta, glazed ceramic and wood, today’s garden containers can be as whimsical and imaginative as the gardener planting them and may include galvanized buckets, old wine barrels, wheel barrows and carts, old coffee and tea pots, as long as the container can hold soil and drains well it could be an option. Julia notes: “I have a large front porch with a 35 gallon container, it’s not a big fancy ceramic thing. It's one of those big plastic grower pots and is a way to recycle the pots. They’re black so they fit any kind of decor.”

Selecting plants

When thinking about ornamental flowering plants for containers Julia suggests “a nice mix of plants with the mantra being: a thriller, a filler and a spiller.” A thriller is the plant that is most prominent, usually taller and the showcase of the container. One suggestion for a thriller is Angel Wings (Senecio canadensis) with large, fuzzy and dramatic leaves and a white flower. Other potential thrillers found in local displays are canus (Canna ‘Pretoria’, ‘Tropicanna’, and ‘Black Knight’) or purple fountain grass (Pennisetum setaceum ‘Rubrum’). A filler adds mass and fills in the middle layer of the container. It can be a flowering plant that does not grow very tall and compliments the selected thriller. Some examples might include Heliotropes, Angelonia, Begonias, Coleus, Lantanas, and Plectranthus. A spiller is a plant that has a beautiful trailing habit such as petunias, calibrachoa (million bells) and nasturtiums. Kathy reminds gardeners to “keep scale in mind with these three elements so your design has balance as well as interest and remember to place plants with similar growing requirements together.” 

Containers are great places to grow vegetables and herbs. Most vegetables need at least six hours of sun with leafy vegetables like lettuce, spinach, chard and other greens tolerating more shade than root crops (potatoes, beets and carrots). Fruiting crops like tomatoes and peppers will not thrive in shade (WSU Extension). Julia reports great success growing lettuce, beets and carrots in 35 gallon plastic containers because they are large and deep enough. She points out that herbs can also be successfully grown in containers, with “thyme easy to grow and beautiful and sage something you can just tuck in and it will take off.”

One of the key components of growing plants in containers is soil. WSU Extension notes that a good commercial potting soil may have advantages over garden soil as it is light, drains well and holds moisture in. Julia reminds gardeners that the soil needs to provide all the nutrients for anything grown in a container. She points out that “it's a good idea to refresh the plantings and potting medium every three years which is also a good time to prune roots of larger sized plants so they don't outgrow the container.”

Happy gardening!

Resources: WA State Extension (free publications for gardeners).

Ask a “Master Gardener” plant clinics will be held at the Charles Pink House at the Port Townsend Library (first Tuesday of the month: 12–2 p.m.; January to December) or at the Jefferson County Library (second Saturday of the month: 1–3 p.m.).    

Michele Koomen has been a volunteer for the Master Gardener Program since 2024, serving as a community educator in gardening and environmental stewardship.