What you need to know about growing tomatoes on a balcony

By Dorothy Dobbie

Don’t be intimidated. Tomatoes are easy to grow anywhere, including on balconies. They just need lots of light and warmth, decent soil, good drainage and consistent watering.

The biggest challenge with balcony gardening is temperature control. The balcony either gets too much sun and heat or too little, and often there is an issue with wind. Tomatoes enjoy moderate temperatures, not extremes. They are unhappy at temperatures that dip below 10 degrees Celsius or rise above 29 degrees Celsius; they prefer temperatures around 21 degrees Celsius.

Consistent watering during fruit development is key. Too much or too little, or sudden change, can all send them into sulking fits that can result in fruit damage. Underwatering to the point where they dry out will cause blossom end rot, that nasty black stuff on the bottom of the fruit that makes them so unappetizing. Drying out can block the calcium needed in the blossom to develop the fruit. Adding eggshells to the soil will do little if the soil has enough calcium and most does. (By the way, yes, you can cut away the bad part and eat the rest.)

Too much water can cause splitting. Long-time tomato growers attribute this to sudden rain, but it is the sudden rush of water, not the rain, that causes the damage.

Excessive heat will cause curling leaves and blossom drop but when temperatures return to normal, this will end, and new blossoms will emerge. Catfacing, unsightly puckered skins and funny shapes, can be caused by both too much heat and too little, two conditions that interfere with pollination development.

On the prairies the sun is fierce and hot, so catfacing may result from direct exposure. While leaf removal to expose the fruit to more light for ripening may work in murkier environments, in areas with intense sunlight, the leaves help to shelter and cool the fruit, which will ripen on its own even if it is still somewhat green when picked. Just set it out on the counter.

What to plant

There are two types of tomatoes: the ones called indeterminate that grow on a vine and keep on growing, and the ones called determinate that grow in a bush form, generally much easier to manage in a small space. Both types can be grown in a container.

The disadvantage to the indeterminate types is that they need staking because they will keep on growing, reaching as much as 20 feet. The advantage is that they keep on producing until freeze-up so you have a continuous harvest. They produce flowers and therefore fruit along the sides of their shoots.

The disadvantage to determinate tomatoes is that flowers grow at the end of their shoots so that they produce all their fruit at the same time. The advantage is size; they stop growing around three to four feet tall.

Both need some sort of support. A tomato cage works best for the bush varieties, while staking may be better for the indeterminates. Most heirloom tomatoes are indeterminate.

If starting your tomatoes from seed, make sure you start them at an appropriate time.

Know what tomatoes to grow

The easiest tomatoes to grow, if you are a novice, are the round, cherry varieties which are sweet and juicy and like long hours of sunlight. They are not as fussy as the big beefsteak types. Indeterminate, they keep on giving until freeze up. You will often see these sold as hanging baskets covered in fruit and flowers. Cherry tomato varieties are a great choice for the casual or beginner gardener. Just keep them evenly watered and provide a dose of fertilizer every couple of weeks.

Grape tomatoes are oblong and smaller than cherry tomatoes. They are often determinates but can be either. They are not quite as juicy as the cherries.

Roma or plum tomatoes are smallish, oblong tomatoes with firmer flesh. They are also determinates, good for harvesting all at once and making tomato sauce or preserves.

Beefsteaks are the big fat tomatoes, firm but juicy and great for sandwiches. They come in many sizes and can be determinate or indeterminate.

Heirloom tomatoes come in many colours, shapes and sizes and are generally grown for their more intense taste.

When choosing tomatoes, consider the time to harvest which can vary greatly. If you are starting them indoors this is an important factor to keep in mind so you will know whether to get started in February or April.

Growing conditions

While tomatoes like sun it may be best to say that they like six to eight hours of light. Really intense sun makes them unhappy. Soil should be slightly acidic (add peat moss) and don’t over fertilize with nitrogen or you will get lots of foliage but little fruit. Feed them a balanced fertilizer.

Don’t crowd them. Grow one tomato plant in a deep four- to five-gallon, well-drained pot, using potting mix as opposed to garden soil. Be sure to fertilize every two weeks or so.

If your balcony has access to an outside water source, consider hooking your plants up to an irrigation system on a timer. Lee Valley sells once especially designed for decks.