How to Choose and Maintain Climbing Plants
Climbing plants are chosen for their suitability to clothe a pergola so that it remains as an open structure: if they are too rampant, the form of the framework is lost, spoiling the effect. A single climber may be the most effective way to cover a pergola: too many climbers all vying for attention may produce an unsatisfactory result. Whatever you choose, note its pruning and other requirements to ensure that it suits the site and gives you the best display.
Supporting Your Plants
All climbers need a helping hand early on to twine around pergola posts and scramble over beams. Encourage your plants to climb by securing vertical wires onto the posts and attaching horizontal wires to the crossbeams and rafters. Tie the shoots to these, releasing them and retying as the stems thicken, if necessary. Greater coverage will be achieved if wires are also stretched between the rafters, or, for a shadehouse effect, add a trellis or wooden slats across the top of the pergola. Allow the plants to grow straight up the wires to reach the top of the pergola quickly or, if you prefer the posts to be generously covered, let them fill out by twining the plants around each post and tying them in. Bare stems at the bottom of posts can be filled in by annual climbers.
Plant the climber a short distance away from the post to give the roots space. Pull back and tie in the stems. Be sure to also plant on the outside of the post, not within the pergola.
Run plastic-coated galvanized wires through hoops on the posts and beams, then train the climbers onto them.
Tie the stems onto the wires with soft twine; be careful not to damage them. Retie as they grow, if necessary. Climbers twined around posts will also provide maximum cover.
- Check the plant label or a reference book to determine the exact pruning requirements of each climber.
- Take care that you prune at the right time of the year to encourage flowers. Getting it wrong may mean the loss of flowers for an entire season.
- Some climbers need light pruning after flowering, while others need hard pruning to encourage new growth.
- Prune vigorous climbers regularly to keep them in check; aim to maintain the structure's shape and to allow easy access.
- Use pruners and long-handled pruners on new growth and a pruning saw on old, thick wood.
- Quick-growing annuals, such as morning glory (Ipomoea), will cover the bare stems of vigorous climbers.
- Be sure to keep vigorous fruit climbers, like grapes, under control.
- For best results choose the right exposure for sun-loving, flowering climbers, such as passionflower (Passiflora)