How to grow vegetables on a balcony or patio

A balcony or a paved courtyard will grow a genuinely useful amount of food, and the reason most attempts at it go sideways isn't the size of the space, it's that a pot behaves nothing like a garden bed. It dries out in a day instead of a week, it heats up through the side as well as the top, and up off the ground it cops wind that the yard below never sees. Allow for those three and the rest is ordinary gardening.

Work out what light you've actually got

Stand out there a few times across one day and watch where the sun lands, because people are almost always wrong about their own balcony. Down here north is the sunny aspect, so a north facing balcony gets sun most of the day and a south facing one is in shade for most of the year. West facing is the tricky one, because it gets the afternoon sun and that's the part of the day that does the damage to plants in pots.

Most vegetables want 6 hours of direct sun. Fruiting crops like tomatoes and capsicum want that as a minimum and will sulk on less. If you've only got 3 or 4 hours, don't fight it, grow the leafy things instead, because lettuce, spinach, silverbeet and most herbs will do fine in part shade and will actually last longer there through summer.

Pots, and why bigger is easier

Small pots are the single most common reason a balcony crop fails, because a 200mm pot in full sun in February can dry out between breakfast and dinner. Go as large as you can carry when it's full, and check what the balcony is rated to hold if you're going really big, because wet potting mix is heavy.

Depth matters as much as width. Carrots and other root crops want at least 300mm of depth to make anything worth pulling. Herbs and salad greens are happy in something shallow. And every pot needs drainage, so if the one you like has no holes in the bottom, put some in with a drill before you fill it. Use a saucer under anything sitting on a balcony so the run-off doesn't end up on whoever lives below you, and tip the saucer out after rain rather than leaving the pot standing in it.

One more thing about pots that nobody mentions. A dark coloured pot in full afternoon sun gets hot enough to cook the roots against the inside wall. Pale pots, or a pot shaded by a plant in front of it, are worth thinking about on a west facing spot.

Use potting mix, not garden soil

Garden soil compacts into a brick in a container and drains badly, so it wants to be a proper potting mix. Mix a slow release fertiliser through it at planting, then follow up with a liquid feed every couple of weeks once things are growing, because every time you water a pot you wash nutrients out the bottom of it. That's the trade for the good drainage and it's why container plants are hungrier than the same plant in the ground.

What to plant, and when to sow it

  • Salad greens. Lettuce, rocket and spinach, sown any time from about February through to November, and picked leaf by leaf rather than pulled.
  • Radishes. Three to four weeks from sowing to pulling, which makes them the one that convinces a sceptic. Sow most of the year, and avoid the hottest part of summer.
  • Herbs. Basil from October once it's warm, and parsley, chives and thyme through most of the year.
  • Cherry tomatoes. Sow or plant from October after the frost risk, and give them the biggest pot you've got plus something to climb.
  • Capsicum and chilli. October onwards, same as tomatoes, and they want the sunniest corner.
  • Cucumber and climbing beans. From October, grown up a trellis so they take no floor space.

Grow upwards

Floor space runs out long before growing space does. A trellis panel against the wall, a few stakes in a pot, or a hanging basket off the rail turns one square metre of floor into a fair bit of crop. Cucumbers, climbing beans and cherry tomatoes will all go up happily. Just tie things in properly, because wind on a balcony will snap a loaded stem that would have been fine at ground level.

Watering a pot

Check before you water rather than watering on a schedule. Push a finger into the mix to about 5cm, water if it's dry at that depth, leave it if it isn't. Water in the morning where you can, and water until it runs out the bottom, because a splash on the surface only wets the top couple of centimetres and the roots below stay dry.

In the middle of summer a pot in full sun may well want water twice a day, and that's normal rather than a sign you've done something wrong. Mulching the top of the pot slows it down a lot.

Pests on a balcony

Aphids and caterpillars find their way up regardless. Look under the leaves once or twice a week and squash what you find, because on this scale hand picking genuinely works. A pot of marigolds or alyssum in among the vegetables brings in the insects that eat aphids.

While we're here, crushed eggshells get recommended constantly as a snail barrier and they don't work, so don't waste your eggshells. Snails walk straight over them. Pellets, a beer trap or a torch after dark are what actually deals with snails.

Shop related products

Did you know we also stock potting mixes, pots and planters with saucers, bamboo and plastic coated stakes, polypropylene trellis panels and loose vegetable seed by the variety, radishes included, in the shop. Not all of it is on the website, so give us a ring on (08) 8536 4333 to check what's on the shelf, or come and pick your pots in person in the garden centre.

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Pots are the part of gardening I'm worst at, purely because I forget them, so put yours somewhere you walk past every single day.

Candeece

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