Your balcony, however small, is a valuable splash of green in a concrete urban jungle,
but its benefits are far more than just aesthetic: When you plant produce on your
balcony you are not only creating a relaxing haven and a handy source of ingredients
for your lunch, but you’re benefiting the wider environment, too.
It looks better
A bare balcony is a depressing sight and a wasted opportunity. Fill it with plants and
it becomes vibrant, softening the hard lines of the city and giving you a space to pause
It tastes better
Grow fruit and vegetables on your balcony and you can experience the wonders of
fresh food—sweet carrots, meltingly ripe strawberries, and crunchy greens. You can
also grow produce you can’t easily buy, such as purple snow peas and yellow cherry
tomatoes. With the merest effort you can be self-sufficient in herbs and never again
have to let those plastic packs of parsley from the grocery store turn to slime at the
back of the refrigerator.
It reduces food miles of fruit and veggies
There is something undeniably satisfying about being able to pick greens from outside
your kitchen and know exactly where and how they were grown. When you start
growing some of your own food, you quickly learn about and appreciate what is in
season and what is local. When you have eaten French beans you have grown yourself,
those little cellophane-wrapped green sticks flown in from thousands of miles away
don’t seem so convenient after all.
It keeps cities cool
Built-up areas trap heat, making average ambient temperatures in cities up to 5
degrees warmer than in the countryside. With global warming set to continue, urban
temperatures will only increase. Planting on roofs and, to some extent, balconies,
insulates buildings from the heat of the sun by as much as 20 percent, thus reducing the need for expensive and energy-devouring air conditioning. In Osaka, Japan, sweet
potatoes were hydroponically grown (that is, in nutrient solution rather than soil) on
the roof of an office building and this cultivation method was found to protect the roof
significantly from the heat of the sun, as well as provide a useful harvest. In
Singapore, Changi Hospital grows tomatoes hydroponically on its roof—yielding 440
lb. of tomatoes annually and reducing the heat on the roof. In cold countries, planting
on roofs has the opposite effect—it traps heat and cuts down on expensive heating
It reduces pressure on city drains
Every time it rains in a city, water rushes into the drains where, in the case of London
and New York, it mixes with sewage before being processed. This system worked
well when it was constructed years ago, but since then many roads, buildings,
sidewalks, and parking lots have been built, meaning more rainwater is forced into the
drains as opposed to being safely absorbed by the soil. This is why people get so
concerned about front yards being paved over for car parking. A sudden heavy
downpour can overload a city’s storm drainage system so that, unable to cope, it
dumps the rainwater-sewage combo in rivers or the sea.
By planting on your balcony or roof you create a sponge that holds rainwater for
some time before it runs down into the drains. Even a small delay of 20 minutes can
make the difference between a functioning city drainage system and one that is
dangerously overloaded, so by greening your outdoor space you can make a really
useful contribution. Capturing rainwater in rain barrels to use on your plants is an even
more helpful step.
It reduces air and noise pollution
Plants on a roof or balcony will improve air quality by absorbing carbon dioxide
emissions and releasing oxygen. A green roof will also absorb urban noise pollution
—from airplanes to traffic.
Planning your piece of edible sky: balcony basics
A garden high above the ground is a unique environment with its own advantages and
challenges. The sun may shine all day and pests such as slugs and snails struggle to
climb up to reach your crops, but the wind might just take your hat off. Here’s how to
make sure your garden in the sky is safe, peaceful, and productive.
Is it going to stay up?
Balconies are generally constructed to support the weight of people, so a few pots are
usually not going to be a problem. If you’re worried, though, use lightweight pots, such
as plastic liners hidden by woven willow baskets, and site them nearer to the house or
over load-bearing supports. Similarly, roof terraces will also have been designed to
withstand large loads and should have no trouble holding up the number of potted
plants you’d expect in an average domestic setting. However, if you’re thinking of
more ambitious projects, such as very large pots, raised beds, or laying soil over the
whole roof, it’s a good idea to consult a surveyor or structural engineer first.
Obviously, if you’re planning to create an “unofficial” roof terrace—customizing a flat
roof that wasn’t built to have people and plants on it—you will need to seek the
relevant planning permissions first as well as advice from a structural engineer to find
out if the roof will need to be reinforced.
Load-bearing areas are generally positioned around the edge and above internal
supporting walls, and it’s here that you should put heavy pots, water features, and
seating. If you have a balcony that is suspended from the side of a building, don’t put a
lot of heavy pots in one place; rather, spread the load around, putting the heaviest
items nearest the building.
Earth, wind, and sunshine
Sunny? Shady? Does your hat stay on? These are the sort of things you need to think
about when you plan your garden in the sky. But there is one thing you can almost
always be sure of: up high it is generally much more exposed than at ground level, so
you will undoubtedly be contending with the wind.
There are two ways to deal with the wind. The first is to plant wind-tolerant
plants; many of these are coastal—hedges of grasses and bamboo or those that form
dense evergreen blocks, such as box or Elaeagnus x ebbingei. In the edible world,
wind-tolerant crops may include hardy herbs such as rosemary and bay, low-growing
crops like greens and strawberries, tough fruit trees like olives, or vegetables like
carrots, potatoes, or dwarf bush beans.
The other solution is to construct some form of protection by erecting screens.
Trellising or bamboo or reed screens, available from all garden stores, are great for
this since they filter the wind a little, rather than forming a barrier that whips it up,
over the top, then down again to scatter your Sunday papers. Trellising, of course, can
be used to support climbing plants—adding valuable height to any garden design.
Bamboo or reed screening is less appropriate for growing plants up, but it is gentle on
the eye, extremely good value, and can be easily fixed to posts using plastic cable ties.
Keep in mind, though, that screens do tend to block out the view, so you may have to
compromise on height if you want to see that lovely urban skyline. Also, work out
which direction the prevailing wind generally comes from before you put up any
windbreaks, as you don’t want to block out your views needlessly. This is as simple
as standing on your balcony for a couple of minutes over a period of several days and
judging which way the wind is blowing.
Wind will also have an effect on the pots you can use to plant your crops. The
lighter the pot, the less weight you’ll be adding to your balcony or roof terrace, and the
less difficult it will be to get it up there in the first place. However, the downside is
that light pots can skate across a roof terrace on a windy day—even furniture can
travel the length of a roof if you don’t choose wisely. If your balcony or roof terrace is
windy, either secure light containers by tying them to railings or fixings or choose
heavier ones such as terracotta that will stand firm in a breeze. Low, heavy trough
planters are the most wind-resistant of all.
One of the great benefits of sky-high spaces is the amount of sunshine you get.
Anyone with a small urban garden will know how frustrating it is when your precious
crops and flowers—not to mention your sunbathing zone—are shaded by other
buildings and trees. Up high, this is much less likely to happen. Of course, the opposite
can then occur: too much exposure to sun, scorched plants, and a need for endless
watering. But in the North this isn’t likely to be a huge problem, and it’s easy to attach
shade screens to the railings of a balcony or string up one of those shade sails in the
warm South. For a more permanent shade structure, you could attach a retractable
fabric awning to the building that you can roll down on hot days and roll back up if the
wind starts to become strong.
Don’t write off the bits of your outside space that seem unpromising. Areas that
are hidden around corners or are shady all day long could not only be useful for
storage of pots, compost, the barbecue, and deck chairs, but could also be the perfect
place to put a wormery. This is an excellent way of turning all your uncooked kitchen
scraps and plant prunings into a nutritious compost that you can then feed to your
plants in a circle-of-life kind of way. When deciding on the position of dining tables
and chairs, think about where the sun hits the balcony in the morning and at lunch and
dinner time. Is there potential for a sunning spot, or a place for a couple of chairs and
a cool drink after a hard day?
Water, water everywhere
All roofs—even flat ones—are generally built on a slight fall so that rainwater can
drain away into gulleys or drains. Check which way the gradient goes on your roof and
bear it in mind when positioning pots, as water will seep out from pots when you’ve
watered them and you won’t want to block its escape by putting something in between
them and the drain, such as a raised bed or planter.
All roofs have a waterproof membrane and it’s really important that this is not
pierced during the construction of your roof terrace, or else rainwater will then drip
down and get into the building. Even installing lights on spikes could damage a
membrane, as could securing pergolas or railings—so be aware.
The whole issue of saving rainwater has become an important one as of late, and
we are continually urged to reduce the amount of water that is lost into the drains.
Collecting rainwater in a rain barrel from the roof is a great idea in a roof garden,
because then you’ll have it easily on hand to water your plants—something you’ll
really appreciate when the alternative is dragging it in quantities from the kitchen
several times a day, or the expensive fitting of an outside tap.