In Parts 1 and 2 of this series, we looked at growing vegetables from cool climates in containers. We will now turn our attention to the production of tomatoes,a plant from a warm climate.
Making the right choice
Tomatoes have three different growth habits: determinate, indeterminate and semi-determinate. Indeterminate cultivars produce stems and clusters of fruit continuously, as long as the weather permits. Determinate and semi-determinate plants stop growing once they have produced a certain amount of fruit.
Indeterminate varieties are less compact, flower later and require a bit more care (staking, pruning) but produce more over a longer period. In general, fruit from indeterminate varieties are more flavourful.
Growing tomatoes in containers
Most tomato varieties can be grown in containers.Some even produce better results. If you like large tomatoes (375–750 gr) such as Brandywine, Celebrity or Cœur-de-bœuf, keep in mind that they will not be beating any size records if grown in a container. However, you will get flavourful fruit if you give them a lot of water, fertilizer and a good volume of soil.
Cultivars that produce small fruit (55–85 gr) suffer much less from the “dwarfing” effect of container gardening.
Don’t skimp on the container
It is preferable to use large containers (45–50 cm in diameter), because tomato plants have abundant, branching root systems that tap deep into the ground. This is all the more important for indeterminate cultivars, which can easily reach two metres high.
If you don’t have room for large containers, choose cultivars specially developed to be grown in pots (Patio Hybrid, Tumbling Tom Red, Tumbling Tom Yellow, Tiny Tim, Lunch Box VF, etc.), which can tolerate a diameter of 25–30 cm.
Lots of warmth, water and fertilizer
Tomatoes need warmth to reach maturity. The ideal temperature to trigger fruiting is 14–17°C at night and 19–24°C in the daytime. Very hot or very cold conditions can lead to malformed fruit or blossom drop.
Tomato plants require regular watering. Dry periods followed by heavy rain or abundant watering will slow growth and cause deficiencies, particularly of calcium. A drip irrigation system is ideal. If you don’t have the very latest state-of-the-art irrigation gear, cover the surface of the soil with mulch and, as soon as the top 3–4 cm of soil is dry to the touch, dampen with lukewarm water.
Tomatoes require a lot of nutrients. Give them potassium-rich water-soluble fertilizer every two weeks.
Pruning and pollination
Indeterminate plants produce side shoots between the main stem and the leaves. These should be removed as they appear, since excessive production of shoots and leaves will take away from the production of fruit. Also prune any lower leaves that are withered or diseased. However, maintain a good cover of leaves, as the fruit should not be exposed to full sun. To encourage end-of-season fruit to mature, get rid of any flowers or fruit that will not have the time to ripen.
Finally, if pollinating insects don’t often visit your balcony, you will have to shake your plants from time to time (between 11 a.m. and 3 p.m. as much as possible) to optimize the flowers’ pollination.
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