Creating a Lush Rooftop Garden: Lessons from a Seattle Deck

Only a year old, this vibrant Seattle rooftop garden has quickly become a family's favorite retreat. While most homeowners might opt for a cantilevered deck or patio, this rooftop oasis offers valuable lessons in container gardening. Four key elements made it come together swiftly: large containers, 60-pound bags of potting mix, a reliable water supply with installed piping and an outdoor spigot, and an enthusiastic owner who tends the garden daily—watering, deadheading, and removing damaged foliage. Come winter, he cuts back the garden, refreshes the top few inches of soil with fresh mix, and hopes the larger plants will thrive for a decade.

Get Creative with Containers

The garden features big glazed pots imported from China and Vietnam, chosen for their size and bright colors. High-fired and glazed, these pots resist winter cracking. Fill them with a rich, sterile potting mix for best results.

Feed and Water Frequently

Container plants exhaust nutrients quickly, so feed every two weeks with half-strength liquid fertilizer and water as soon as the soil surface dries out.

Mix Annuals and Permanent Plants

Repeat filler plants like Bidens ferulifolia and ivy geranium for visual continuity throughout the space.

Don't Shy Away from Trees and Shrubs

Even a crape myrtle thrives here. Smaller pots hold shrubs and woody plants such as Algerian ivy, heather, Hebe, and Hypericum.

Use Upright Perennials for Color Accents

Plants like gerbera, golden marguerite, and snapdragon provide exclamation points of color.

Employ Tender Perennials and Annuals as Fillers

Zinnias and helichrysum add flowery abundance between the structural plants.