Pergola

Pergolas are more than shade structures.

Shade structures protect us from the sun’s summer glare, but they are often poorly made and generally don’t last more than a season or two. Pergolas, on the other hand, are sturdy structures that can provide shade for decades. Let’s find out why pergolas are such a good idea.

Pergolas cool concrete patios and provide climbing structures

Pergolas reduce the heat sink effect

Many homes have concrete patios. Concrete acts as a heat sink that absorbs and then radiates a phenomenal amount of heat in the summer. This is also known as the urban heat island (UHI) effect. As this heat is radiated, it can cause several problems:

• burnt feet and pet paws (concrete can reach 140°F!)
• baked container plants (put spacers underneath to keep them off the concrete)
• scorched soil and underground roots
• dead soil microorganisms and earthworms
• higher risk of sunburn damage (to plants and humans)
• increased water needs for nearby plants
• higher air conditioning costs

Shade can reduce the ambient temperature by as much as 15°. If it’s 100°F outside, that can make a huge difference in your comfort, your plants’ health, and your cooling bill.

Pergolas as protection

The word ‘pergola’ comes from the Latin word ‘projecting eave’. People have been creating shade for themselves since, well, since there have been people! At first, pergolas provide only marginal protection from the elements. Over time, as climbing plants make their way up and across the top of your pergola, the shade protection can become significant. After many years of growth, your pergola may even offer something of a rain barrier!

A structure by any other name…

Pergolas are spaces defined by upright posts or beams and an open lattice above that is normally used as support for climbing plants. Many people call pergolas by other names: arbors, gazebos, and bowers, but they are technically incorrect. The words describe slightly different versions on a theme, but there are differences:

• pergola - an attached or anchored garden structure covered with trained climbing plants
• arbor - a smaller, free-standing garden alcove with sides and a roof for climbing plants
• gazebo - a solid-roofed structure that is open on the sides, often round or octagonal  
• bower - generally a living tunnel created by overhanging trees meeting in the middle
• green tunnels - living plants trained over an arched trellis to create shady tunnels

Green tunnel (Andrew Bossi) CC BY-SA 2.5

Pergola: DIY, ready-made, or custom

This decision is one of those time-or-money questions. Most of us have one or the other, but rarely both. If you have time and tools, you can find designs online and at your local library for a wide variety of pergola styles. The building process is relatively straightforward. If you prefer more convenience, there are ready-made pergolas with the lumber already cut and drilled and all you do is assemble the pieces. If you have money to spare, the sky is the limit. You can custom design a pergola to fit your space and style, creating a unique, artistic sanctuary in your garden or landscape.

Plants and pergolas

One of the biggest problems with vine-covered pergolas is weather. [I’m speaking from personal experience here.] One night of freezing temperatures and your trumpet vine, wisteria, or honeysuckle can be killed off, leaving behind a skeleton of its former self. Luckily, in most cases, the root system will be able to recover thanks to that heat-sink concrete patio slab. Of course, covering an 8- or 9-foot high pergola with some square footage takes time. You may want to supplement your shade with shade cloth for the first few years. And if freezing temperatures are predicted, hang some old fashioned Christmas lights, drape plants with fabric (without touching), or fire up the BBQ grill. [Just make sure you don’t start a fire somewhere else!]

Pergola plant selection

As you select plants to grow up your pergola, make sure they are suited to your microclimate in terms of temperature, sun exposure, and soil. This will help your plants thrive and reduce your workload. You should also consider bloom time. Some people install multiple plants with different bloom times and colors for a longer season of flowers. Of course, my personal favorites are the edibles! Here are some popular plants for pergolas:

Training your pergola plants

Most climbing plants, even self-clinging varieties, will benefit from a little help, at first. You can gently tie new stems to the nearest pergola post, leaving the ties in place until the tendrils have taken a firm hold on their own. Once plants have reached the top of the pergola, these ties can be removed.

So, more than just shade, a pergola can provide support structure for climbing plants, reduced water and electric bills, increased home value, and even art!

• bleeding heart
• bougainvillea
• clematis
• grapes (edible)
• honeysuckle
• hops (edible)
• jasmine

• kiwifruit (edible)
• morning glory
• passionflower
• sweet pea
• trumpet vine
• wisteria