Late summer heat frying your veggies? Here are four ways to keep your plants cool and your garden productive into autumn
The gourd plays it cool in the shade
By early August it’s apparent the heat and sun of summer are taking a real toll on the garden.
While the days aren’t as long as they were when summer started, the sun is still high in the sky allowing strong light (and the resulting heat generated by that UV light) to reach the surface. Also, both the air and soil are now much warmer than they were six weeks ago.
The vegetable garden in mid June
The vegetable garden in mid August
This creates special problems for mid-to-late summer annuals and vegetables. Ripening fruits and vegetables can get burned by sun scald. Plants will drop leaves or stop flowering and fruiting to conserve water and energy. Seeds and young plants that like their soil and air temperatures in that Goldilocks zone of 60 to 78 degrees (16 – 26 C) won’t germinate or will stop growing.
Fortunately, all of these problems can be minimized or eliminated just by throwing a little shade at them. Ideally, you want to provide shade that offers 40% – 70% sun blocking — higher percentage for brighter/hotter areas, lower for those that may be partially shaded during the day.
Here are four different shade methods to keep your garden productive going into autumn.
Types of shade coverings
The type of shade covering you choose will depend on what you’re trying to protect. All shade covers reduce the amount of sunlight reaching the plant to one degree or another. Some will also reduce the amount of heat. Reducing light is good for plants that might get burned in the sun, but are otherwise okay with the heat (sweet peppers are a good example). Others, however, need both less sun and less heat.
Horticultural Shade Cloth
Horticultural shade cloth on tomatoes to keep them blooming
Horticultural shade cloth (not to be confused with shade cloth for deck coverings, etc.) is the kind of shade cloth you see being used in nurseries, greenhouses operations and farm fields. It’s a woven plastic with a finished edge and grommets that can be used to fix it in place. The plastic weave is available in various widths and lengths, as well as densities to block anywhere from 20% to 90% of the sunlight (the sweet spot is usually in the 40% – 60% area).
Lightweight and flexible, horticultural shade cloth allows air to easily pass providing air circulation and preventing heat buildup. It’s light enough to drape directly on lager plants without crushing them. You can place it on smaller plants too, but it’s generally better to support the cloth via wire hoops, poles, etc. to keep it from weighing on the plants.
Pros: Available in many different sizes and sunblock densities. Flexible so it’s easy to fit lots of different shapes and areas. Air easily circulates under it to keep down heat.
Cons: More expensive than other shade coverings and usually only available at nurseries or online. Also, the plastic degrades in sunlight, so it’s prone to falling apart after a few years. Finally, it’s light enough in weight that if you’re in a wind-prone area you’ll need to tie it down to prevent it from blowing away.
Best for: covering rows or large areas that need sun protection.
Door / Window Screen
Screen fabric protecting baby sweet pepper plants
This is the material used for screen doors. It’s made from high density plastic or fiberglass, and available in a variety of lengths/widths, and shades that block anywhere from 30%-70% of sunlight.
This material is stiffer than shade cloth so it requires less support. The holes in the screen are also finer which prevents small insects such as aphids from passing through it. At the same time, the smaller holes also reduce air circulation which means heat can build up under it.
Pros: Long lasting and weatherproof. Comes in a variety of lengths and widths that fit pretty much any raised bed. Stiff enough to support itself with a minimum of additional supports. Small holes prevent insects from penetrating.
Cons: Not as flexible as shade cloth, so it doesn’t drape well. Smaller holes mean less air circulation and more heat buildup underneath. Also, in wind and rain it needs to be secured so it doesn’t blow away or weigh down the plants.
Best for: raised beds and sturdier plants that need more shade but not necessarily less heat.
Burlap landscape fabric
Protecting peppers from sun scalp with a burlap tent
Burlap is an all-natural fabric made from jute. It comes in both loose and tight weaves that allow varying amounts of sunlight and air to pass through. Like horticultural shade fabric, burlap is very flexible and requires support to keep it from weighing down plants.
Two types of burlap weave
Additionally, it will absorb water, making it heavier and potentially squishing tender plants if it’s unsupported.
Pros: Cheap and 100% organic. Loose weave burlap will allow good air circulation and 50% – 70% shade coverage. Easy to cut to different lengths and widths for various uses.
Cons: Stretches and degrades over time, requiring extra support. Absorbs water so it can get heavy. Additionally, the tight weave burlap (70%+ shade coverage) allows less air circulation, so it’ll act like a blanket if not supported so that air can came in from the sides.
Best for: Tenting specific plants, areas that need limited (smaller) shade coverage.
Hanging gourd garden shading the western bed in the vegetable garden
One of my favorite forms of providing shade because it’s multi-purpose. Tall, vining plants grow up a trellis over a bed, providing shade to those underneath, while also producing fruit (or flowers) and a visually attractive garden feature.
You can use any tall vining plant — pole beans, long vine cucumbers, morning glories, or my favorite – gourds. Just make sure you’ve got enough support and the vining plant is one that grows over a long period or it’ll die back exposing the plants under it.
Pros: Natural, provides good air circulation and shade, makes use of vertical space for additional fruits/veggies/flowers, and makes an attractive garden feature.
Cons: Requires trellising and more substantial support than other shade methods. May also require more maintenance if you have to prunes plants to keep them in control.
Best for: Garden rows or beds with plenty of room above and on either side for trellises/plants.
Which type of garden shade is right for you?
As you can see, garden shade materials vary widely and each has its own strengths and weaknesses. I happen to use all four types in my gardens.
I find the horticultural shade cloth works best on large plants that are well supported or on row beds (using wire hoops for support). During the hottest part of summer I’ll cover my tomatoes with it to keep the temperature down. Tomatoes will stop flowering when it gets too hot, so this is an easy way to keep them fruiting through the dog days of summer. I also use shade cloth on the roof of my greenhouse to keep the temps down and prevent seedlings in it from boiling.
Screen fabric is useful in smaller areas where I need to cut the sun but not necessarily the heat. I use it in the keyhole garden to protect young pepper plants, keeping the screen from crunching the little peppers by propping it up on bamboo skewers.
Solar lights make the gourd garden an evening attraction
Burlap is useful to make small “tents” over sun-tender plants as well as for covering beds where I’m direct seeding crops that enjoy heat (e.g., bush beans), but need the water kept in the soil until they sprout, grow leaves and make their own shade. Another bonus with burlap is that it can be used in other seasons as a blanket, warming the soil when it would otherwise be too cold to grow anything.
The vertical garden is probably my favorite, but least practical shade method. It takes some extra effort to get it set up, but by the time the heat of summer is in full swing, it provides a shady canopy that keeps the soil cool enough to grow things that don’t thrive in the heat such as lettuces, broccoli & cauliflower, and cilantro.
It also looks pretty awesome at night because it’s lit with inexpensive solar powered fairly lights.
Regardless of whether you use just one or all of these methods, you’ll find that a little shade goes a long way toward beating the heat in the hottest parts of summer. Give it a try — your plants and garden will appreciate it!