Choosing what tomato variety to grow
Tomato growers are lucky: they have thousands of varieties to choose from. Likewise, they are unlucky: with so many varieties to choose from how do you make a good choice? Read the gardening press, ask a fellow gardener, review the seed catalogues: all good starting points, but still, choosing what tomato variety to grow for your needs can be tricky. To make the choice easier, tomatoes must be broken down into their basic elements. And then, and only then, can an informed decision be made.
Plant growth habit
Tomato plants have two basic growth habits:
• Indeterminate (aka Cordon)
Tall growing, cordon types whose main stem and the side shoots they produce can grow on almost indefinitely. To keep the plants under control, the side shoots should be regularly pinched out, leaving only the main stem to develop. These in turn need staking or trellising to keep them upright and off the ground. Some authorities even suggest pinching out their growing tips to promote fruit ripening at the end of the season.
• Determinate (aka bush)
Bushy or shrubby plants whose growth is naturally restricted by self-stopping
main stems and side shoots. Consequently, they need no pruning and are grown without support. They are often early maturing and are suitable candidates for growing outdoors and in hanging baskets.
There are also some varieties that are defined as semi-determinate. These can grow quite large, and might benefit from some pruning and support to keep them off the ground, but the main shoot will eventually terminate.
Fruit colour
To fully understand fruit colour in tomatoes both the colour of the internal flesh and the colour of the skin must be considered:
• Flesh
The colour of all immature tomato fruit is some shade of green, which is due to the presence of chlorophyll. As the fruit ripen, the colour of the flesh changes as the chlorophyll breaks down and various carotenoid pigments, including lycopene and beta-carotene, start to build up. Most varieties turn red, though other common colours are yellow (e.g. Honey Drop) and orange (e.g. Sungold). In a small number of varieties, some of the chlorophyll is retained, and where no red pigment is produced the flesh remains green (e.g. Green Zebra). If, however, there is an accumulation of red pigment, then the mixture of red and green produces flesh that is red-brown (e.g. Black Cherry).
• Skin
The colour of the skin surrounding a tomato is either yellow or colourless. This is important since the skin interacts with the flesh to produce a range of colours on the surface of ripe, intact fruit. Some examples of the interactions and the colours they produce are as follows:
Red flesh + yellow skin = red tomato; e.g. Patio Plum
Red flesh + colourless skin = pink tomato; e.g. Malinowy Ozarowski
Yellow flesh + yellow skin = yellow tomato; e.g. Sun Belle
Yellow flesh + colourless skin = white or ivory tomato; e.g. Snowberry
For more information on fruit colour, see: Carol Deppe (1993, 1st edition, though there is also a 2nd edition); Breed Your Own Vegetable Varieties. Little, Brown and Company. Pages 211-212.
Fruit shape and size
Other than colour, one of the most defining physical features of a tomato variety is the size and shape of its fruit. Fortunately, most varieties fit quite naturally into a manageable number of categories that are normally quite distinct from on another:
• Standard or classic
The type most commonly found in shops, it includes the varieties Orkado and Matina. Fruit are approximately 5 to 7cm in diameter and are round though normally slightly flattened. They have two or three locules, and their surface is generally smooth.
• Cherry
Small-fruited up to 32mm in diameter. The shape ranges from slightly flattened to slightly oval. The quintessential type for eating fresh, it includes the varieties Sungold and Sakura.
• Mini or baby plum
Small, oval-shaped fruit with a diameter similar to that of a cherry tomato. Ideal for fresh eating, typical examples include the varieties Modus and Golden Sweet.
• Cocktail
Size-wise, bridges the gap between the standard and cherry types.
• Beefsteak
The giant among tomatoes, fruit are about 7 cm or over in diameter. They are multilocular (with five or more locules), have a flattened shape, and are often strongly ribbed. Ovi’s Romanian Giant is a typical example.
• Plum
Medium-sized, oval-shaped fruit that have a pasty texture due to a high level of dry matter. They are at their best when processed into sauces, and Nova and all varieties with ‘San Marzano’ in the name fall within this category.
• Miscellaneous
A minority of tomatoes don’t fit neatly into the mould but are worth a look-at for their novelty value alone. They are often disguised as other objects, such as the larger-sized, somewhat heart- or top-shaped varieties like Cuor di Bue (oxheart). Likewise, there is also a small, pear-shaped type that comes in red and yellow; another one that is reminiscent of a bell pepper; and a variety that is similar (well, sort of) in shape, size and colour to a strawberry.
Earliness
‘Earliness’ refers to the time it takes between planting and the first fruit to ripen. In this respect there are significant differences between varieties. For example, in a trial of 31 tunnel-grown indeterminate varieties, we noticed about four weeks difference between the earliest and latest ones to ripen.
Earliness is of the utmost importance for tomatoes grown outdoors, as plants that ripen early avoid the late season onslaught of cool, wet weather and the inevitable blight it brings. And because determinate types are often early maturing, they are recommended for growing outdoors, though a few of the early maturing indeterminates, such as Sungold and Matina, might also be worth a try.
Yield
To a great extent, maximising yields is what gardening is about. After all, why put all the hard work into growing a crop unless there is a worthwhile harvest at the end? Yield in tomatoes is a product of the number and the size of fruit a plant produces, so varieties that produce a good number of large-sized fruits are bound to be the best yielders.
Flavour
Tomatoes are the quintessential sweet-and-sour food, and the best-tasting fruits have high level of both sugar and acid. The balance is not always ideal, however, and high acid and low sugar levels result in tart fruits, while the reverse situation produces fruit that may be very sweet but quite bland. The worst possible scenario is a combination of low sugar and low acidity, resulting in an insipidness that cannot be corrected by even a sprinkling of sugar and vinegar.
Choosing the right variety is an absolute must, but it is also essential to provide the right growing environment if optimum acid and sugar levels are to be achieved. Restricting water and growing the plants in full sunlight increases sweetness, while adding potassium fertiliser to the growing medium will give acidity a boost.
While sweetness and tartness are the dominant features of taste, volatile compounds contribute to both the aroma and flavour that make tomatoes what they are. Literally hundreds of these chemicals have been identified in the fruit, and though the roles of most remain obscure, others have been positively connected with the characteristic aroma found in fresh tomatoes.
OP vs hybrid
Most modern breeding has focused on the production of hybrids, and there is a preponderance of these available in the catalogues. Breeding open pollinated (OP) varieties, however, hasn’t been completely abandoned, though it must be said that most of the OPs currently available have been around for quite awhile.
Heirloom tomatoes are particularly old OP types, and ones grown in the Uk normally have an American origin. They consistently receive good reviews in the gardening press, though the hype is often undeserved. Many are quite late to mature; most have little of no disease resistance; and – the greatest insult of all – some varieties don’t even taste very good. That said, varieties well-worth growing do exist, such as the beefsteak Ovi’s Romanian Giant, which is (as the name suggests), a Romanian heirloom variety.
Heritage vs heirloom
Heirloom tomatoes are particularly old OP types, and most heirloom tomato varieties available in the UK have an American origin. They consistently receive good reviews in the gardening press, though the hype is often undeserved. Many are quite late to mature; most have little of no disease resistance; and – the greatest insult of all – some varieties don’t even taste very good. That said, varieties well-worth growing do exist, such as the beefsteak Ovi’s Romanian Giant (which is a Romanian heirloom variety).
The term ‘heritage’, rather than ‘heirloom’, is reserved for British varieties of vegetables that are 50 years or older. Though they don’t come with the same romantic cachet as their American counterparts, seeds of a few heritage tomatoes varieties, such as Moneymaker and Ailsa Craig, are still around. Though flavour, yields and disease resistance might be considered less good than many modern varieties, these remain surprisingly popular with amateur vegetable gardeners.
Disease resistance
As a general rule, there is only one disease that is likely to be a problem in a well-managed crop of tomatoes grown by amateur gardeners. This is blight, and it tends to be more of an issue with tomatoes grown outdoors. There are now several varieties that have blight resistance, and if growing tomatoes outdoor should be grown.
Modern hybrids, at least the indeterminate ones bred for greenhouse production, are resistant to a host of other diseases, including tobacco mosaic virus.
This is not to say that OP varieties completely lack disease resistance – quite the contrary. For example, Red Alert, an older British variety, displayed some blight resistance in a Which? Gardening trial conducted in 2011, while Roma, a determinate plum tomato, has stated resistance to both verticillium and fusarium wilts.
©Sea Spring Seeds