A curtain of vines

Thinking about ways to reduce our energy use for cooling next summer, I hit on the idea of shading some west-facing windows at the back of the house with foliage. I don’t want to block the three full-length windows that provide our main view of the garden. But a pair of windows near the southwest corner could use some summer shade. Vines could be just the thing.

These windows get a lot of afternoon sun in summer

    The Department of Energy explains that vines can lower the temperature of a house in three ways. In the process of evapotranspiration, plants actively transport water, and when it evaporates, it cools the surrounding air. Shade reduces solar gain, of course, and vines can blanket the side of the house, creating an insulating air space. Put together, these contributions can reduce temperature shifts by 50 percent.

Vines can keep a house cool-photo Michael Palmer

    I’m not proposing to cover the whole west side of the house in vines yet. My idea is to start with a large container of fast-growing vines to keep the sun off that pair of windows.

    When I put up supports, I’d like to leave space between the vines and the house to permit air flow. I’m picturing a wooden frame attached to the siding that would hold some lattice or wire fencing to support the vines. Maybe I can attach hinges at the bottom of the frame so I can swing it down when it comes time to paint the house again.

Lattice attached closely to the garage wall leaves little air space behind it

    I’ve learned a lesson from a large wooden planter I placed directly on the ground in a shady corner. Tree roots grew up into the potting mix, making it hard to remove and replace old growing medium in the spring. This time I’ll prevent that by standing the planter’s corners on bricks to leave an air space that the roots can’t jump.

    Next will come the fun part: choosing which vines to grow. I could go with classic fast-growing flowering climbers such morning glory (Ipomoea purpurea), moonflower (Ipomoea alba), or mandevilla (Mandevilla spp.). These all originate in Central America. I could choose edible options: scarlet runner beans, cucumbers or squash. 

Morning glories are lovely and grow fast

    But I'd prefer to use native vines. I’ve already got two trumpet honeysuckles (Lonicera sempervirens), a cross-vine (Bignonia capreolata), and a trumpet vine (Campsis radicans) close enough to the proposed site that I’d like to try something different.

Trumpet honeysuckle is going strong in a dry spot against the house

    Last summer I grew a blue passionflower (Passiflora caerulea) vine in a container on the deck, wrapping its long stems around a black metal obelisk stuck in the pot. That one’s from South America. There’s a native cousin called maypop (Passiflora incarnata) that looks pretty. It’s reportedly a woody vine in the Southeast that dies to the ground in colder areas, which would serve my purpose. Growing it in a planter would curb its tendency to aggressive root spread.

Maypop, a native passionflower-photo H. Zell

    Another native possibility is woodbine (Clematis virginiana), a vigorous grower with white flowers August to October that could accept cutting back in winter. A quick search uncovers warnings about its spreading by seed, though, so maybe not.