I live in Toronto (zone 6) and my backyard has tile. I’m planning to plant a climbing hydrangea In a planter box along my East fence. What would the dimensions need to be? Would a 2 ft deep planter be enough? And what would be the length and width? Thank you.
Climbing hydrangeas (Hydrangea anomala subsp. petiolaris) are hardy to zone 4 so should adapt well to being planted in a container. Keep in mind that although it may take 2 – 3 years for it to establish itself and grow a good root system, the mature plant can reach 30 to 50 feet. Your container not only needs to be weather proof against freezing and thawing but also needs to be large enough to accommodate the mature plant. Because it will cling to the fence, the above ground weight of the plant should be largely borne by the fence. In addition, hydrangeas don’t have a tap root so a 2′ deep container should be adequate. Of course the bigger the container you can provide, the better it is for a permanent planting.
I notice that it will be against an east fence. Does that mean it will get full sun in the afternoon or is it shaded? The amount of sun will affect watering and also the spring freeze and thaw process. A larger container will hold moisture better as well as protect the roots from winter cold and excessive summer heat.
Below is a link to a publication about growing trees in containers. Although it is geared to trees, most of the same principles can be applied to growing a climbing hydrangea in a container. Note the sections regarding size and design of containers and the type of substrate. type.https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-023/430-023_pdf.pdf
I am also including a link to a site about container gardening, specifically how to prepare your containers for winter.
Once established you will enjoy your climbing hydrangeas for many years. I can personally attest to their longevity and their beauty.