I have a metal pergola in my backyard (4 metal posts with slatted roof, 10 x 10 feet). I want to plant two Boston Ivy vines at the bottom of two of the posts (the roots will be buried directly into the lawn) and have the vines snake upwards and cover the entire metal roof of the pergola. Issues: We have fierce western sun so hopefully this vine grows super fast and is very hardy.
Question: How long will it take for the Boston Ivy to grow up an 8 foot post and then cover a 10 x 10 foot pergola roof? Again, I plan to use to large Boston Ivy plants.
Thank you
p.s. Is it safe to mix two vine species together, eg Boston Ivy one side and Virginia Creeper the other?
Thank you for contacting Toronto Master Gardeners.
Boston Ivy (Parthenocissus tricuspidata) is a rapidly growing, vigourous deciduous vine that does well in full-sun to part shade and is hardy to Zone 4. It should be planted in medium, well-drained soil. Boston ivy has shiny, maple-shaped leaves that turn brilliant red in autumn. The vine is a tendril climber meaning that it does not need support rather it clings by small disks located at the end of the plant’s tendrils. This quality makes it very difficult to remove when grown on a building. Your choice of training it up a pergola is a good one.
The vine has very small white flowers in spring that are almost hidden by the foliage, but these turn to berries that become visible in the fall when the vine’s leaves drop.
Virginia creeper (Parthenocissus quinquefolia) is another rapidly growing, vigourous deciduous vine that will also grow well in full-sun to part shade locations. Virginia creeper is slightly hardier than Boston ivy, hardy to Zone 3. It is a five-leaved ivy that will exhibit the best fall colour when grown in full-sun. This vine tolerates many soil conditions but grows best in medium, well-drained soil. Virginia creeper also produces berries that attract birds. Virginia creeper may also damage walls, so a trellis is a good choice. This vine is also a tendril climber that climbs by clinging to its support. Virginia creeper will spread along the ground and it would be important to train it up the pergola for support. It can be invasive if it spreads horizontally.
Both vines need regular pruning to keep them under control.
Growing one or both vines on your trellis would be a matter of personal preference and should not pose any particular problems.
You might be interested in these two articles:
https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c267
http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=l490