As the weather warms up and we spend more time outside in the garden, entertaining, pottering in the garden or just watching the kids play, the need for shade becomes very evident. Options for shade include natural shade created by plants and artificial shade created by shade cloth, umbrellas or sails.
As I drive around the city, hills and country, I see houses desperately in need of an appropriately chosen tree (or two or three) to cast summer shade on the hot exposed sides. Apart from the obvious aesthetic benefits that trees add to gardens, an appropriate tree can also help to make a garden more water wise, by making it cooler and reducing evaporation. Breezes that pass-through areas shaded by trees are cooled, acting as natural air conditioning to cool your home and surrounds. By reducing the temperature of your house, less air conditioning will be required and this in turn reduces your electricity bill. Trees also add to the value of your home and suburbs with shady street trees have higher property values.
Decisions to be made when choosing a tree include whether it should be deciduous or evergreen. Even though deciduous trees lose all their leaves in winter, this is often invaluable to let in the winter sunshine. Also, although a tree may be evergreen, it may shed its leaves over the whole twelve months of the year, as opposed to a deciduous tree losing its leaves over a one-month period. Leaves of deciduous trees make great mulch and compost – they need not be viewed as a nuisance but rather precious raw materials for recycling.
Size of a shade tree is an obvious consideration, and when choosing a tree nothing beats getting expert advice from qualified horticulturists, who can suggest how big a tree will be in ten to twenty years. Many gardening texts talk about tree size, but this may refer to the size in the wild state, perhaps of a hundred-year-old specimen, or not under South Australian conditions.
Other factors to consider are the tree’s features and seasonal interest, and where possible try to choose a variety with a number of features. While most people consider flowers, few think through how long the tree flowers for, with spring flowering trees having a very fleeting period of show. We often fall in love with a tree when we see it in bloom, and do not think about what it looks like for the rest of the year. So apart from flowers, consider what the foliage of the tree is like. Is it attractive in its own right? Generally, we look at the leaves for a lot longer than the flowers, yet this is often only a secondary consideration. Think about what the foliage does in autumn too, and even find out whether the leaves hold on the tree once they are coloured, or do they drop immediately? Ornamental fruit trees such as crab apples are a great way to attract birds and add some interest to the garden in autumn. Bark is another wonderful feature that is often overlooked. Finally consider what shape you would like the tree to have, perhaps a spreading round headed tree or something more upright.
There are so many wonderful trees to choose from, so make sure you get expert advice from your local nursery or garden centre.
Another way of achieving shade in the garden is by constructing features such as pergolas, arches and tunnels. In the old days, a pergola referred to an open structure, typically with a vine growing on it, yet now many people have covered pergolas, clad with metal or plastic sheeting. Such enclosed structures are anything but cool, and in fact can become heat traps, hence the placement of fans underneath them.
When considering a climber to grow over a pergola or arch, the same questions need to be asked that would be considered when selecting a tree – does it have a number of features and benefits during the year? Popular choices for climbing over structures to provide shade are wisteria and crimson glory vine.
Now the reality is that when planning for natural shade by planting a tree or a vine over a pergola, the plant is going to take a few years to get to the desired size. On one level this means that the sooner you can get planting the better, however on a practical note, it also means that you might need to consider how you can get some temporary shade in the meantime. You can use shade cloth or sails for temporary shade over pergolas or choose to use bamboo blinds to give a Mediterranean feel. You might also decide to wait till after the heat of summer to plant if you don’t think you can look after new trees well enough, particularly with regards to watering. However even if you choose the variety you want and plan for autumn planting, you could even start to work on the soil so that when the tree does finally go into the ground, it will power away.
Over the last few years I have done a few experiments here at Sophie’s Patch with vertical vegies such as New Guinea bean, Tromboncino, climbing squash, caigua and climbing spinach. These could be used to create short term shade for a few years until more permanent plantings get big enough. However, to grow these incredibly quick-growing, warm-season vegies, you need to have good soil. I sowed seeds of these into warm, fertile, organic improved soil in mid to late November after the last frosts and created shade or shelter by the end of January and into February. Now if you were down in town and frosts aren’t an issue you could sow a month or more earlier and have shade created that much sooner too. Read more about these at https://sophiespatch.com.au/2019/04/06/favourite-vertical-vegies/
When growing vegies over summer it is essential that you are prepared to cover and protect them on days of extreme heat. While vegies need sun to grow best, and not all need to be protected, the blast of summer sun during heat waves can be too severe. The temperature difference under shade cloth is significant and while I haven’t measured any ambient temperatures in my shaded areas, I have measured surface temperatures with my trusty infrared thermometer and I have found that the difference in temperatures on the sawdust path in my vegie patch between full sun and an adjacent path under 50% shade cloth is at least 10 to 15 degrees cooler.
The vegies I like to protect with shade cloth are leafy greens like lettuces which become bitter if allowed to dry out, kale which is often best as a cooler season crop, Asian greens like Bok choy, tomatoes, capsicums and cucumbers. I don’t try and cover my eggplants although their fruits can get sunburnt if there is not enough leaf cover and fruit is exposed to the hot sun. Pumpkins, zucchini, squash and tomatillos all grow out in the exposed heat of my garden.
By contrast, growing vegies in too much shade many cause some vegetables to flower and fruit poorly and growth of plants like tomatoes to become soft and sappy which can attract white fly. So, like many things in gardening, it is a balancing act. Some gardeners erect permanent shade over their summer patch using 50% shade cloth. Others set up a structure which they can then throw some shelter onto their vegies for the really hot days. This will ultimately be decided by the position and conditions in your vegie patch. This summer I am doing an experiment where I am growing one section of vegies in permanent shade and another under movable shade where I only cover them on days over 35 degrees. While at this stage I think movable shade will be the preferred option, I will be able to see at the end of the season.
Putting shade over my wicking beds is easy as I have metal hoops which I also use for insect exclusion netting and I now have shade cloth cut to size which I can readily clamp on. Recently I saw these taller shaded canopies over wicking beds at the Henley Community Garden and thought they were great. They have used electrical conduit which is cheap and often available in salvage yards and secures the bottom with metal clamps made for it. They have also made easy to use roll up sides so they can create shade when they need it.
However, popping shade cloth over sections of my main vegie patch has either been hard work due to its size or required many hands. It is also tricky once you need to shade taller crops like tomatoes on stakes. In the past, I have used umbrellas, scrappy bits of shade cloth and any piece of fabric I can get my hands on like old sheets, and not only has it looked dreadful it’s blown off with the hot winds we often get on those extreme days. So, now I have invested in shade cloth which is big enough and I have taken inspiration from other gardens I have visited and set up a series of wires which the shade cloth can be dragged across. It still needs some fine tuning as you can see in this video however once I have finished, I want it to be a one person job.
Finally, be aware of direct sun on the sides of corrugated metal raised vegie beds and plastic pots. Simply shading the hot sides of beds with bales of pea straw can make a huge difference, as can growing sprawling crops to hang over the edge, planting upright plants around the edge or clustering pots together to create shelter. Radiant heat from adjacent paving, brick walls or metal fencing can also cause problems for tender crops, so use climbing vegies to create shade (https://sophiespatch.com.au/2019/04/06/favourite-vertical-vegies/) or physical barriers such as bamboo screens to reduce this heat.
My conclusion after considering all this is that on a hot, summer day, nothing could be more pleasant than sitting in a cool shady spot in the garden. So, if you don’t already have any shade, why not plan ahead for future years.