I am looking to buy a rose for a corner in my backyard along the east fence. It gets a lot of afternoon sun, especially higher up, with strong light 12-6pm more or less (but it’s not sunny all the time on the floor; in fact, moss grows nearby). I am placing a 4 ft x 1 ft x 1 ft planter box in that spot. I was thinking of planting a climbing rose in that corner, would that work? What variety of rose do you recommend? And if a rose won’t do well, can you recommend something else? Thanks
Climbing roses can be lovely, but growing one successfully in the planter you describe is unlikely. Most varieties of roses make good container plants but you must match the size of the rose to a container that accommodates its growth. Unless miniatures, roses have deep, fibrous root systems that need lots of room. Many climbing roses grow more than 4 metres high, with numerous branches, and therefore have very large, deep root systems.
Is there a reason you don’t want to plant directly into the soil, instead of in the shallow planter? Is it because of the soil condition? You mention that there is moss growing there, which may signal some soil problems. Mosses are shallow rooted, acid loving plants that can grow in part to full shade. Because they are shallow rooted, they thrive on compacted soil with poor drainage. Also they prefer a pH of 5.0 – 5.5 , whereas roses grow best at a pH closer to neutral 6.0 – 7.0. My guess is that you want to use a planter to avoid the soil issues, which is a good solution … just not for very large, deep-rooted climbers.
Here’s one suggestion for a fast-growing, floriferous, annual climber you might consider for this season, if you don’t want to create a new garden bed along the fence, improving the soil: Thunbergia alata (Blackeyed Susan vine) To 6 feet (180 cm) 5-petalled orange blooms with chocolate-purple eye. Trailing or twining vine. Water regularly for best performance.
If you do want to use the planter for a flowering perennial vine, you may be successful with some shade-tolerant clematis types are the alpine clematis, Clematis alpina, and sweet autumn clematis, Clematis paniculata (terniflora). Note that they prefer alkaline conditions, so will not survive in the acid soil condition I suspect, so the planter is the best option. Here’s Landscape Ontario’s guide to growing clematis.