What does a veteran gardener do when she moves into a townhome that has only a tiny patio surrounded by a three foot wide bed? This same gardener also loves all forms of hydrangeas, some of which can grow very large. My solution was to attach several Oakleaf hydrangeas to the brick wall that partially surrounds my patio. It was my hope that this technique would prevent these enormous plants from taking over my patio while supplying me with a wealth of blooms. This experiment has been far more successful than I ever expected, resulting in long Oakleaf blooms hanging from the wall (inside and outside the patio) for 3 months of the year. In the fall, the leaves turn brilliant colors, adding another season of interest (1).
This attachment technique (similar to espalier) is very easy, but it’s important to pick the right Oakleaf hydrangea. Use the variety Hydrangea quercifolia ‘Snowflake’ (a native) because it is the only Oakleaf with drooping blooms (2). Also, ‘Snowflake’ blooms at least 3 times longer than other Oakleaf hydrangea varieties, continuing to put out new florets all summer as the blooms age (3).
PRUNING THE HYDRANGEA
Training an Oakleaf hydrangea to a wall or other support involves pruning each plant to only 1-3 main “trunks” or stems (4). If they are small plants, they should be allowed to grow for 3-4 years without much pruning or training. The third year after they are planted, identify the largest stems coming out of the soil to form the trunks on the hydrangeas. Then remove any smaller stems at ground level. Over time, remove all extra growth from these main stem-trunks and continue to attach them to the wall. Do not remove the top leaves and stems as these will eventually form a small canopy. Also, do not cut back the tips of the top growth because this is where the blooms develop. Every spring and fall, remove all small suckers that sprout around the roots of the plant as well as any new growth on the trunk. Be brave! Be brutal! Be patient. The plant will reward you with lovely peeling, patchy textured bark and fabulous blooms.
ATTACHING TO A WALL
For me, attaching the stems to the brick wall was, at first, a challenge. I finally found something called “hook cable clips with steel nails” (5). I used black hooks so they would not show. I am sure there are better ways of attaching the stems, but I do not know what they are. These hooks worked well. They do not hook around the stems. Rather, they they are used to secure the wire or tape which keeps the stems close to the wall. I hammered the hooks into the mortar about halfway up the wall (18” or so). (No mortar has ever been dislodged or even crumbled, and no hooks have fallen out.) I attached two or three hooks above each plant, spacing them out. Then I used soft copper wire to attach to the hooks, and when the stems were long enough, I looped the oppose end of the wire loosely around the stems to encourage the plants to grow up the wall and over the top. (Later I used green plastic tape.) Over the next couple of years, a few more hooks were added closer to the top of the wall and the stems were secured (6). The plants were encouraged to cascade over the wall simply by pushing the elongating stems in that direction.
If you do these three things – obtain ‘Snowflake’ hydrangeas, keep them pruned to 1-3 stems to form the trunks, and attach them securely, but loosely, to a wall, fence or trellis, they will faithfully reward you with a unique and breathtaking display in your garden or landscape year after year (7).
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