Solanum lycopersicum
Thousands of years ago, tomatoes were common in South America and Mexico and were used in cooking more than eaten raw. They were first brought to Europe by the Spanish conquistador Cortés, in the 16th century.
Tomatoes are in the Solanaceae or nightshade family, and this caused them to be viewed with suspicion in Europe for some time. Unripe fruits and leaves contain tomatine, which would be poisonous if eaten in large quantity, but ripe fruits contain no tomatine.
In the UK, one of the first people to grow a tomato plant was John Gerard the surgeon, who wrote in his Herbal of 1597 that the fruits are unfit for human consumption. It was another 200 years before tomatoes were in widespread use.
Harvest period
- Days from seed to first harvest: 90, often more.
- Best climate has warm summer days of 22–35 °C/72–95 ° F, and at least four months between last and first frost dates.
Why grow them
Great flavour, colour, abundant fruiting over many months, a range of plant and fruit sizes – there is much to like about tomatoes. Tomato plants grow well in warmth but also tolerate a certain level of coolness, more, for example, than aubergines and peppers.
- They can be grown in many ways and you can fit them into almost any growing situation.
You can choose from a huge range of varieties, for the fruit size, colour and flavour you like. They will compare favourably to most tomatoes of commerce!
Tomatoes with much less flavour happened from the 1950s, after a phenotype (genetic trait) was discovered that enabled breeders to ensure uniform ripening. The tomatoes were of even colour all around, with no green top (greenback), but unfortunately also had reduced sugar and taste levels.
- Well-grown tomatoes are a source of umami flavour – savoury. The other six main tastes are sweet, salty, sour, bitter. astringent and pungent.
- Use of salt increases umami tastes, hence the increased flavour of tomatoes with salt.
Fruit or vegetable?
Botanically, tomatoes (also cucumbers, peppers etc.) are fruits or berries. However, in general usage we call them vegetables because their sugar content is much lower than that of fruits.
- Another way to clarify this difference is to ask whether you eat a food as part of the main course or as a desert. Tomatoes, cucumbers etc. are eaten with the main course – they have a savoury rather than sweet flavour and therefore are vegetables.
Pattern of growth
Different varieties of tomato plants grow small or large, and tall or bush. Results vary according to whether you grow them outside or under cover. This lesson concentrates on the latter because it is based around my experience of growing tomatoes in cool summers, where there is often not enough time for plants to give a worthwhile harvest of ripe tomatoes outside.
- Plants grow for three or four months before they produce worthwhile amounts of fruit.
- During summer, tomato plants put on a phenomenal amount of growth: 1) creating new stem and leaf, 2) developing trusses of new fruits, 3) ripening tomatoes. They are doing all three of these things, each of which needs a lot of energy, at the same time!
- Plants are killed by the first frost of the autumn, and often before that their growth has slowed in the darker conditions.
Tomato types
- Bush plants are called determinate and are annuals – they ‘crop then stop’, without trailing stems.
- Cordon plants are called indeterminate and are perennials, as long as there is no frost in winter. Their natural habit is trailing. We grow them as annuals, vertically upwards with support.
- Cherry tomatoes are usually sweet and small, although often larger than a cherry in size, with a corresponding reduction in weight of harvest compared to beef tomatoes. They ripen quite early, especially Sungold and some determinate varieties.
- Beef tomatoes are the largest in size and have fewer cavities in the fruit, therefore contain more flesh and proportionately less skin. The texture is often dense (meaty, hence the name) and full of flavour, but they ripen later than cherry tomatoes.
- Medium-sized tomatoes with firm skins are most common in stores and supermarkets, often of a variety selected for yield ahead of flavour. Mostly they are grown hydroponically for maximum harvest, to pay the bills – the price of tomatoes relative to other goods has declined steadily in the last 60 years.
You can grow hydroponically at home, but this requires a fair amount of kit. I do not recommend it unless you have sufficient time to monitor all the variables. It needs more knowledge and investment compared to growing in soil or containers. Your harvest will look good, but is missing important nutrition from soil microbes.
Brix, a measure of sugar
A way to measure sweetness is called brix, and uses a refractometer. Brewers and winemakers keep this device handy to check the sugar content of their must, which tells them how much alcohol there will be after fermentation.
I have used a refractometer over a few years, with the juice of different tomatoes grown in different ways – the table below gives an idea of their sweetness. Higher figures mean more sugar.
- The highest figure I secured was a fully ripe Victoria plum at 19.4. Here, beetroot and carrots are 8 or 9. The table offers clues about how to increase tomato sweetness: reduced watering is the main one – this is easier in pots or containers than in soil outside if it has rained. Choosing suitable varieties clearly influences flavour.
Tomato variety and where grown
Brix level in refractometer
Dorada pot
10
Dorada soil outdoors
6.5
Primabella pot
9
Primabella in pot, kept dry 24.9
10.2
Primabella in soil, same day 24.9
5.2
Resi pot
9
Rosada F1 greenhouse
11
Rosada F1 polytunnel
9.5
Rosella greenhouse
6.5
Sungold F1 greenhouse and polytunnel
8
Trixi polytunnel
6.5
Velocity F1 polytunnel
3
Yellow Brandywine
5
Katy apple (ripe)
11
Victoria plum
19.4
Brix is sometimes claimed to represent nutritional quality, with higher numbers indicating more nutrition. This is not totally proven, but higher numbers certainly indicate reduced water content, and therefore you have denser food with more dry matter.
Under cover
Inside a structure you have the possibility of growing indeterminate plants up strings – this increases harvests a lot. I refer to these plants as cordon tomatoes.
- In areas with cooler summers, growing under cover gives much more chance of worthwhile harvests, in summer as well as in autumn.
- When summers are hot and long enough, tomato stems have time to grow longer than a structure is high. You need a device to hold spare string, which enables repeat lowering of the now-empty lower stems down to soil level.
- The active flowering and fruiting zone of cordon tomato plants spans roughly 1.8 m/6 ft. Below that level are non-working leaves and finished trusses.
Plants grown under cover can be kept dry, which is a huge advantage in damp climates because it prevents late blight. Your key knowledge is that late blight cannot develop on dry leaves – see below.
Outdoors
There is more wind outside and indeterminate tomato plants need tying to strong stakes. There is a fair amount of time needed for securing them.
Bush plants are quicker and easier to grow than cordons outside, but take longer to harvest and fruits on the ground may be damaged by slugs; also, leaves may stay wet and suffer late blight.
Suitable for containers/shade?
Tomatoes are the container vegetable par excellence. The main criterion is a container large enough to grow the variety you choose – cherry tomatoes are most successful. Site in sun where possible, unless your summers are hot.
You need a compost with plenty of nutrition. The photos below illustrate what happens to plants when they run out of food. It’s not the end of the world and you still get a harvest, but it’s smaller and finishes sooner.
There are many proprietary foods available for tomato plants. You need a feed for container growing, compared to the little or no feeding needed for plants in soil. Also watering is much more frequent than for tomatoes growing in soil, where the root run is more extensive.
Make sure you have the time and means to water regularly. There are proprietary watering kits with pipes and timers, but that investment may well not be repaid in the value of your harvest, depending on how you calculate it.
Large containers can grow cordon tomato plants with stakes inserted in the container. Or you can grow special varieties for hanging baskets. Do try a few things!
Varieties
My favourite varieties reflect the growing conditions here – summers warm but not hot, with the risk of late blight outside and five months between last and first frost.
In warmer climates, I would favour beef tomatoes over cherry tomatoes. In cooler climates, look for fast-ripening varieties.
- Sungold F1 ticks every box – it crops early and tastes amazing, plus can be grown outdoors in sheltered gardens. The yield is not heavy and the skin is prone to splitting.
- Sungella F1 is a larger version of Sungold, with more harvest and less flavour.
- Sakura F1, a red cherry, offers great flavour and larger fruits than many cherry varieties.
- Gardeners Delight was an early commercial cherry tomato variety in the 1970s, when it was smaller and sweeter than it is nowadays. The varietal maintenance has not been thorough because there is more money made from selling hybrid tomatoes. My last two attempts at growing Gardeners Delight resulted in medium-sized fruit with very average sweetness and tough skins.
Crimson Crush and Mountain Magic, both F1, resist late blight without being immune to it and have decent flavour. Crimson Crush is a medium-sized beef tomato.
I have had top results from open-pollinated cherry varieties offered by Culinaris in Germany. Resi, Primabella, Primavera and Dorada all have good flavour. They grow well in cooler conditions and have some resistance to late blight.
Beef tomatoes grow better under cover, in cooler climates.
- Black Russian has a rich flavour, soft skin and deep colour. It’s not really black, just purple. I tried Indigo Rose once, which is sold as a ‘black tomato’, and found it tough-skinned with little flavour.
- Brandywine tomatoes are large and taste wonderful – there are red, pink and yellow varieties.
- Super Marmande is an old variety from South West France, of variable quality according to who has been selecting the seeds. The flavour and texture are superb, fruits are medium-large. Possibly these were the origin of the huge beef tomatoes I found in a neighbour’s garden in South West France, which we called Mami tomatoes in honour of the old grandmother who grew them every year.
- Hybrids such as Gigantonomo, Big Boy, Country Taste and many others, have been bred for the exceptional size of their fruits. All of those that I have grown and eaten also taste good!
- Feo de Rio and Feo de Rigordo grow super tasty, red beef tomatoes of dense texture and top flavour.
Commercial tomato varieties are mostly red and of medium size. They have tough skins so that they transport well, plus have a long shelflife. Their water content is high because this results in a high yield for making a profit. Do look at the brix result of Velocity in the table.
- Orkada Fi tastes better at least.
- A medium-sized red fruit of decent flavour is Matina.
Clear
Use a sharp trowel or knife to cut around surface roots, enabling plants to come free but leaving most of their roots in the ground. Cut stems to 10 cm/4 in lengths before adding to a compost heap.
It is safe to put any blighted material on the compost heap. Blight spores die once the plant tissue has decomposed, and even in cool heaps this will be before midwinter.
Follow with
Tomatoes grown outdoors finish by mid-autumn, which means there is little time for new plantings, especially after bush tomatoes.
However, cordon tomatoes give many possibilities. Options are to underplant or sow winter and spring vegetables, starting with spinach in late summer, then salads in early autumn and spring onions in mid-autumn.
- Spread a little compost before undersowing or planting, because you may not find space to spread it in late autumn, between the new vegetables that are already growing.
