If I could only grow one crop in containers, I’d choose tomatoes. Homegrown, these colourful little jewels sing with flavour, and taste totally different from the round, flavourless red things with a curiously grainy texture available in supermarkets, also labelled – a bit misleadingly in my opinion – tomatoes. To my mind, there’s more distance between a ripe homegrown tomato and its mass market equivalent than any other container crop.
Given proper love and attention, tomatoes can also be highly productive in containers. Each plant will give you several kilos of bright red, orange, yellow or even black fruits. Grow a few plants and you’ll be eating them everyday from August to mid October. And, unlike some vegetables, it’s hard to find you have too many: I have been known to struggle for culinary inspiration when faced with a glut of runner beans but excess tomatoes never seem to be a problem.
To nurture the generosity of the tomato in containers, you need to remember that it’s a greedy plant. It needs sun, food and water – and does best with lashings of all three. It’s also important to choose the right variety, a decent sized pot, and to stake climbing varieties well.
As many small urban spaces are often overshadowed by surrounding buildings, the first thing you need to check is that you have enough sun. You really need at least six hours sun a day for most tomatoes to do well. You might, at a push, get a reasonable yield from a small cherry tomato in just five or six hours sun, but less than that and it gets more unlikely that you’ll see the fruits turn from promising green to luscious, juicy red.
What variety? If you’re growing outdoors in the UK, you’ll get a better harvest in most summers from a cherry variety than a large beefsteak tomato. Also look out for “early ripening” varieties, as these are more likely to be productive in a poor summer, and to fruit before the arrival of the dreaded blight (a nasty fungal infection that decimates tomatoes). You can then choose between bush or vining varieties. Dwarf bush varieties are my choice for hanging baskets or smaller containers. My favourite bush variety for hanging baskets is the aptly named “cherry cascade”.
Vining tomatoes make good use of vertical space by going up. Support them well, using a cane, a tomato cage, or my favourite solution: string. Secure the string to a hook about two metres above the tomato, and wind the string round the tomato as it grows. You’ll need to pinch out the side shoots of vining tomatoes as they grow (if you’ve not done this before, a “how to” video on YouTube can be instructive). Top cherry vining tomatoes varieties for pots include Black Cherry, Gardeners Delight, Sungold, and Blondkopfchen. Grow all four and you’ll have an amazing mix of yellow, red and black tomatoes that will look beautiful together in any bowl.
To help satiate the tomato’s desire for food and water, it’s best to grow all but the smallest varieties in decent sized pots – 10 litres or more. A container with a water reservoir is a good investment for tomatoes. It makes watering easier and you’ll get higher yields.
If you decide to grow tomatoes in a hanging basket, the challenge is watering. Choose the largest basket you can find, add 15% perlite or biochar to the soil to improve water retention, line the inside of the basket with plastic with holes for drainage, and cover the top with plastic to reduce evaporation. Add an upturned plastic bottle, with a hole drilled in the lid and the bottom cut off. Fill this up each morning and the water will gently drip into the basket during the day.
Tomatoes are best grown in a good quality multipurpose or potting compost. If you have a wormery, mix in 10–15% worm compost to add nutrients and soil life.
Feeding tomatoes regularly is critical for a good yield. At the minimum you need a good liquid tomato feed, high in potassium (K). Any tomato feed from a garden centre will do the job. But if you really want to push the boat out, check out Sea Nymph’s natural seaweed based feed, or BioBizz’s, BioGrow, which has added molasses to feed the microbes in your soil. I also add a 1in (2.5cm) layer of worm compost or manure (from the local city farm) to the top of my tomato containers about half way through the season. They love the extra nutrients and soil life this adds.
Is there a downside to growing tomatoes? Apart from the risk of blight, the biggest one is picking your last tomatoes at the end of the season. You might feel a sense of mourning that it will be eight months before you bite into another tomato which really tastes like a tomato should. But that also serves to make them that much more special when your crop is ready again the next July.
You can get many more tips on how to grow tomatoes successfully in the Vertical Veg Club this month.