Tomatoes are one of the most popular garden plants and understanding how to ripen tomatoes is important when you grow them. Unless you live in a protected greenhouse, your outdoor tomatoes probably fall victim to pests before they get the chance to fully ripen. Or perhaps you have a short growing season.
It seems your only option is to pick them while they are green, but is it easy to ripen them indoors? What is the best method for ripening tomatoes? Also, are there methods that can slow down or speed up the ripening process? Do cherry tomatoes ripen the same way?
In this article I’m going to share the best method for ripening tomatoes indoors, along with some tips and tricks. I know all too well what it is like to have tomato problems, and it can be depressing when you don’t yield much due to problems with ripening.
These days, I have much more success because I ripen almost all my tomatoes indoors. Indoor ripening also taught me how to ripen tomatoes faster or slower. By slowing down the process, it is possible to have fresh tomatoes even in the winter. Using this method, I have more control over when the fruits ripen, and I am much more successful in obtaining a crop of unblemished, tasty red tomatoes.
What Is Ripening, Anyway?
Before we get into how to ripen your tomatoes, we have to understand ripening as a process first. Ripening is the transformation process that gives tomatoes their signature red appearance and their sweet, fresh flavor. When a tomato fruit ripens, the green chlorophyll of the tomato breaks down and red color pigments come to the surface.
Timelapse of a ripening tomato. Created from this video
As it ripens, it decreases in tannins, which are responsible for the sourness of green tomatoes. Ethylene gas, which is present in aging fruits, helps break down cell membranes. As a result the tomatoes become softer. This is why they ripen faster when they are around riper tomatoes. As the tomatoes become softer and sweeter-smelling, they also attract pests.
If left outdoors, most tomatoes will be eaten before they become pink. You will have much better results if you pick them when they are still green, but just beginning to ripen. They can easily be ripened indoors to reach their most delicious, red color.
What Color is Your Tomato?
How ripe your tomato is can be determined by the color on the outside. This standard can be applied to all kinds of tomatoes, including cherry tomatoes. There are 6 tomato color classifications recognized by the USDA: green, breakers, turning, pink, light red, and red:
If your tomato is completely green, ranging from light green to dark green, it is the furthest from being ripe. Once your tomato begins to show a little yellow, pink, or red, it is said to be in the “breaking” stage. When 10-30% of the tomato’s surface is showing yellow, pink, red, or a combination of these colors, it is “turning.”
After the turning stage, your tomato will turn pink, meaning that between 30-60% of the tomato’s surface will show a red color. Then, the light red stage means that more than 60% of the surface is pink or red. The final stage is red, and this is when more than 90% of the surface shows red color.
A Few Words on Other Methods
You might wonder, can I bring my tomato plants indoors to ripen the tomatoes on the vine. You can, but tomato plants carry things like bacteria, microbes, and mold spores, so bringing the plant inside will also contaminate your home. This will quickly contaminate other tomatoes that you have picked off the plant.
Commercial growers might tout ripening methods that include chemical treatments of oxygen and ethylene. However, you don’t need to get that technical. In the right conditions your tomatoes will ripen just fine on their own.
You might think, sun ripened tomatoes are a thing. Doesn’t that mean I can ripen them in a sunny window? Well, not exactly. Light is not required for ripening and it will actually make the skins harder. The heat will cause the tomatoes to ripen too quickly, and if they become to warm they will rot. Sun-ripened tomatoes are different than window-rotted tomatoes.
You can, indeed, ripen your tomatoes in a paper bag, or wrapped in newspaper placed in plastic bags. These methods do work. However, they take longer, and are harder to regulate than the method we’re going to discuss right now!
How to Ripen Green Tomatoes Indoors
There are a variety of methods that can be used to ripen green tomatoes indoors. I have experimented with different methods and tricks for years, and have found that simpler is often better. This method is fairly easy, but it has also given me the most success.
Here is a list of items you will need.
- A wide, flat box or container
- Absorbent material, such as a towel or paper towels
- Dehumidifier (if the ripening area is humid)
Step 1: Pick Your Tomatoes
If a tomato is hit by frost, it will turn dark green and cease to ripen. Therefore, it is important to pick the green tomato off the vine before a threat of frost. Only pick the tomatoes that are shiny and green, or green with a little pink. The smaller, white tomatoes will not ripen well indoors. This goes for cherry tomatoes, slicers, and paste tomatoes.
Step 2: Wash
Wash the tomatoes under cold, running water. You’ll want to use running water so you can wash away all the dirt and bacteria down the drain, and not cross contaminate the tomatoes. As you do this, also remove any stems, so that the stems will not accidentally puncture other tomatoes.
Step 3: Sort
If you have any tomatoes that are soft, bruised, or blemished, separate them from the firm and clean tomatoes. You can attempt to ripen the bad tomatoes, but if they are left with the good ones, they may cause the good ones to rot.
Step 4: Create the Ripening Area
You will ripen the tomatoes in a flat, wide container. Cardboard produce boxes are ideal. You can get these boxes when you buy fruit at Costco or Sam’s Club. However, any cardboard box should work.
The container you use must be made of an absorbent surface, such as thick cardboard. You will need to layer the bottom with something absorbent, like a towel or paper towels. This absorbs moisture from any tomatoes that start to rot. If the liquid from rotting tomatoes touches other tomatoes, it will cause the good tomatoes to rot more quickly.
Step 5: Place the Tomatoes to Ripen
Place the good tomatoes in a layer at the bottom of your container, spacing them 2-3 inches apart. To avoid the spreading of rot, the tomatoes should also be spaced apart so they are not touching.
You can speed up the ripening process by including a ripening banana, apple, or other piece of fruit which will diffuse ethylene into the unripe tomatoes. If you go this route, ensure you’re checking the box frequently as the ripening process will be much faster than it would without them.
Step 6: Store the Container
Store this box in a cool, dry area that is 50-65ºF (10-18ºC). Basements, garages, or indoor porches can all be good areas for storing. High humidity will cause more rotting and a higher chance of mold, so you may need to use a dehumidifier.
Good air circulation is also important for preventing mold. Cooler temperatures, from 50-60ºF (10-18ºC), will cause tomatoes to ripen more slowly. Higher temperatures, from 60-65ºF (15-18ºC), will cause more rapid ripening. Make sure that the tomatoes don’t reach a temperature under 50ºF, or they may go soft and never turn red.
Step 7: Monitor the Tomatoes
Check on the tomatoes every day, or once a week at the very least. Remove any rotting tomatoes as soon as you see them. Check for rot at least every other day, because any rot will spread quickly to other tomatoes. When the tomatoes become 50% red, remove them from your box and continue to let them ripen in your kitchen.
Step 8: Enjoy Your Ripe Tomatoes!
It should take between 3 weeks to 3 months for your tomatoes to finish ripening. Through some careful monitoring and temperature control, you can cultivate a yield of tomatoes that lasts through the winter!
Storing Ripe Tomatoes
Now you may have heard that you shouldn’t store nightshades in the refrigerator. However, that’s just not the case for tomatoes. While it may be true for peppers, eggplants, and the like, tomatoes do just as well when they’re stored in a cool, dark fridge. In fact, they won’t degrade as quickly as if they were stored on the counter.
Especially if you have a perfectly ripe tomato that you’re not going to eat right away, the refrigerator will keep that tomato at the same ripeness it was when you placed it in the fridge. It should keep for up to 2 weeks this way, as long as you haven’t cut into it.
As you might already know, cold tomatoes don’t have as much flavor as room temperature ones. So, when you take the tomato out of the refrigerator for slicing or cooking, let it come to room temperature. Then enjoy its full flavor.
It’s still viable to store your tomatoes on the counter, but they may not last as long. Whether you choose to store them in the fridge or on the counter, turn them blossom end up. As we’ve discussed, tomatoes ripen from the bottom-up, and storing them on their stems will assist in this process.
Not to mention, storing them with the blossom end pointing toward the ceiling distributes the weight of the tomato more evenly, preventing weight-driven deterioration over time.
Frequently Asked Questions about Tomato Ripening
Q: How do I get my tomatoes to turn red?
A: Use the method described above, involving a cardboard box, lined with newspaper or some other absorbant paper. Check above for more details.
Q: Will tomatoes ripen after being picked?
A: As long as they are beyond the “green” stage (see the image above) they will indeed ripen after they’ve been picked.
Q: How long does it take to ripen tomatoes in a paper bag?
A: It takes about a week to ripen tomatoes in a paper bag. You can do it faster with the cardboard box method.
Q: Why haven’t my tomatoes turned red?
A: This usually has to do with conditions that are either too hot or too cold. Temperatures outside the 65-85° range trigger a reduction in compounds produced by tomato fruit that spurs ripening.
Q: Should you pick tomatoes when they are green?
A: During the growing season, try to avoid this unless there are disease and pest issues that instigate harvesting early. You can also remove mature green fruit from the vine to ripen indoors if a frost is looming.
Q: Do tomatoes ripen quicker on the vine or off the vine?
A: As long as conditions are right, they ripen faster off the vine.
Q: What can I do with unripened tomatoes?
A: You can still cook with mature green tomatoes! Fried green tomatoes are delectable. Salsa made with green tomatoes can be just as flavorful. Fritters, chutney, and tomato bruschetta could be made too. Get creative in the kitchen with your unripe tomatoes.