Not all tomatoes have tough skins. Some tomatoes have remarkably soft, thin skins that are easy to slice and bite into. But it’s not necessarily a bad thing when tomato skin is tough. In fact, some tomatoes are bred with tough skins!
Roma and other plum-type tomatoes have been bred to produce thick skin. This makes them ideal for canning and drying. But if you are growing a variety that doesn’t naturally have a tough, thick skin, the cause is usually either because of high temperatures or too little water.
Reasons Why Your Tomato Skins Are Tough
Typically, tomatoes develop tough skins for three reasons. Only one of these is 100% predictable – when you plant a variety that was bred to have a thick skin.
The other causes aren’t predictable. But if you know what they are, you can do something about it.
High temperatures caused by intense sunlight can cause the skin of any type of tomato variety to toughen. So, too, can a lack of water and other severe environmental factors.
Even little cherry tomatoes, which usually have thin, easily digestible skin, will toughen in very high temperatures.
There are also several diseases that cause tomato skins to become tough and thick. Too much fertilizer can also be a factor.
Extreme temperatures will tend to toughen the skins of tomatoes. Intense sunlight raises the temperature and can also scald the fruit.
High temperatures may also slow down the ripening process. If your tomatoes don’t ripen properly, the fruit will tend to have tough skin.
While tomatoes generally like direct sunlight, if it gets too hot, you can provide some shade with shade cloth or shade netting. Ideally, install it over a pergola that enables you to retract the netting when temperatures are not too intense.
Otherwise, just install it over the top, and not on the sides of the structure. Then it will be protected from the intense, overhead midday sun, but the sun won’t be blocked out completely.
Too little water
Tomatoes that get insufficient water often develop thick, tough tomato skins. This often happens when the fruit hasn’t been watered enough in the early stages of growth.
Regular watering and the addition of mulch around your tomato plants will ensure they get enough water. Just be sure not to overwater or you could end up with tomato plants that have root rot!
A good option is to install a drip irrigation system. It will keep the soil moist and also minimize the risk of fungal diseases like the Septoria leaf spot.
Some tomato varieties have been specially bred with tough skins. For example, it is beneficial for tomatoes to have tough skin when they are to be used for preserving, canning, or bottling.
Plum tomatoes, including popular Rosa plum tomatoes, are a good example of tomatoes bred with tough skin. They are particularly suitable for sauces, pastes, puree, and tomato juice, both commercial and homemade.
The fact is that the tomatoes’ tough skin is easier to remove for the canning process. It also holds together better than other types when the fruit is dried.
Generally, any variety of tomatoes that are known to be resistant to cracking will also have a thicker skin.
The good news is that there are some tomato varieties that are less susceptible to growing tough skins than others. These include Tigerella, which bears tasty, medium-sized fruit, as well as several varieties of cherry tomatoes.
Tomato plants need nourishment, but if you feed them too much, this can result in tough skins. Fertilizers with a high potash content are villains in this category.
Many experts recommend rather that you alternate fertilizer with a good level of nitrogen with fertilizer that is high in potassium. Nitrogen promotes leaf growth while potassium promotes fruiting.
There are several diseases that attack tomatoes and lead to tough skins. These include Anthracnose and the Curly Top Virus.
Anthracnose is a fungus that infects the fruit of tomato plants, creating discolored, leathery patches on the skin. Over-watering, rather than under-watering, is the problem here.
Curly Top Virus is carried by pests in the garden, like the sugar beet leafhopper. The fruits get stressed and start to ripen too early.
At the same time, the leaves of stunted plants start to twist and curl upward, becoming leathery and stiff.
This makes the skin tough and uneven. But you’ll probably notice the leaves curling and turning yellow before the disease affects the fruit.
The best course of action is to remove any plants that are infected. You’ll lose out on part of your tomato crop but will stop the virus from spreading to your healthy plants.
One fortunate thing is that because the disease isn’t soilborne, it’s safe to compost the infected plants.
How do you soften the skin on tomatoes?
If you plant thick-skin tomatoes you can expect them to have tough skins. As mentioned above, these types are generally preferred for processing.
You can cook with them, though you can also remove the skin and still eat them raw or puree or juice them.
By quickly boiling and then chilling tough-skinned tomatoes, you will dissolve a layer of the fruit just under the skin without cooking the tomato. This releases the skin allowing it to slide off very easily.
How to prevent tomato skins from getting tough
It’s simple really. If you know what causes tough tomato skins, you can prevent the skins from becoming tough.
Give them enough water and sunlight, but not too much. When the sunlight is intense, provide shade.
And don’t plant varieties that have naturally tough skins!
If you don’t want tomatoes to have tough skin, avoid planting varieties that are known to be thick-skinned. Also, be sure to water them well, but not too much, and to provide shade if they are exposed to excessive heat for any length of time.
It’ll be worth the effort because not only will the skins of your tomatoes be thin, but the flavor of the tomatoes will be tastier too.