How To Ripen Tomatoes Inside

If you have a batch of green tomatoes and want to enjoy them sooner, learning how to ripen tomatoes inside is a simple process. Whether you’ve brought in the last of your garden harvest or bought underripe store tomatoes, these quick indoor ripening methods will help you get the most flavor from your fruit.

The core principle behind ripening tomatoes indoors is understanding the role of ethylene gas. This natural plant hormone triggers the ripening process. By controlling the environment around your tomatoes, you can encourage them to produce and be exposed to more ethylene, speeding things up significantly.

What You’ll Need for Indoor Ripening

Gathering a few simple supplies will make the process much easier. You likely have everything you need already in your home.

A cardboard box, paper bag, or any breathable container.
Newspaper or plain paper towels (optional).
Ripe bananas or apples (for the fastest method).
A room with a stable, cool to warm temperature.

The Paper Bag Method (Quickest & Most Effective)

This is the go-to technique for a reason. It concentrates the ethylene gas around the tomatoes perfectly. Here’s how to do it step-by-step.

Check your green tomatoes for any bruises, cuts, or signs of disease. Use only healthy, blemish-free fruit.
Place the tomatoes in a standard paper bag. Don’t overcrowd them; a single layer is best.
Add a ripe banana or apple to the bag. These fruits emit high levels of ethylene and will act as a ripening accelerator.
Fold the top of the bag over loosely to trap the gas, but don’t seal it tight. A little air circulation is good.
Store the bag in a dark spot at room temperature, like inside a cupboard or on a counter away from direct sun.
Check the bag daily. Your tomatoes should ripen noticeably within 3–5 days.

The Cardboard Box Technique (For Larger Harvests)

If you have a lot of tomatoes from an end-of-season garden pull, a cardboard box is ideal. It offers more space while still containing ethylene gas effectively.

Line the bottom of a cardboard box with a sheet of newspaper or paper towels. This absorbs any excess moisture.
Arrange your green tomatoes in the box so they aren’t touching eachother. Stems should face down.
If you want to speed it up, place a few ripe fruits amoung the tomatoes in the center of the box.
Close the box flaps and place it in a cool, dark area of your home, such as a basement or pantry.
Inspect the tomatoes every other day, removing any that show color or feel soft.

Why Separation is Important

Keeping tomatoes from touching prevents mold from spreading if one fruit goes bad. It also ensures even ethylene exposure and air flow, leading to more uniform ripening across your whole batch.

The Classic Windowsill Ripening Approach

For just a few tomatoes, a sunny windowsill is a traditional choice. It works, but it has some drawbacks compared to the bag or box methods.

How to do it: Simply place your green tomatoes stem-side down on a sunny windowsill.
The Pros: It’s effortless and lets you watch the color change day by day.
The Cons: Direct sun can sometimes toughen the skin or cause uneven ripening. The ethylene gas disperses, so it’s slower.

This method is best for tomatoes that have already started to show a slight blush of color, known as the “breaker stage.”

Key Factors for Successfull Indoor Ripening

Paying attention to these three elements will make a huge difference in your results. Getting them wrong is a common reason for ripening failure.

1. Ideal Temperature Range

Temperature is the most critical factor. The perfect range for ripening tomatoes is between 65°F and 75°F (18°C – 24°C).

If it’s too cold (below 50°F/10°C), ripening stops permanently and can lead to poor flavor.
If it’s too warm (above 85°F/29°C), the red pigment lycopene fails to develop, leaving you with orange or yellow tomatoes.

2. Light vs. Darkness

Contrary to popular belief, tomatoes do not need light to ripen. Ripening is a biochemical process that happens from the inside out.

A dark environment is actually prefered. It helps maintain a stable temperature and prevents the skins from getting leathery. Light is not harmful, but darkness is often more consistent.

3. Humidity and Air Flow

You want a moderately humid environment. Excess moisture promotes rot, while overly dry air can cause tomatoes to shrivel.

A breathable container like a paper bag or open box provides the right balance. Avoid sealing tomatoes in plastic bags, as this traps too much moisture and will cause them to spoil quickly.

Common Mistakes to Avoid

Even with good intentions, it’s easy to make a few errors that slow down or ruin your tomatoes. Here’s what to watch out for.

Refrigerating Green Tomatoes: Never put an unripe tomato in the fridge. The cold halts the ripening process and destroys the enzymes that create flavor and texture.
Washing Before Ripening: Wait to wash your tomatoes until right before you eat them. Introducing moisture before storing them encourages mold growth.
Crowding Tomatoes Together: Piling tomatoes into a bowl or tight basket traps ethylene unevenly and increases pressure and bruising.
Using Damaged Fruit: A single rotting tomato can spoil the whole bunch. Always sort and use only the best specimens for ripening.

What to Do With Ripened Tomatoes

Once your tomatoes have turned a beautiful red (or their final color) and yield slightly to gentle pressure, they’re ready. They are best used within a few days for peak flavor.

If you end up with more ripe tomatoes than you can use immediately, you can slow down the next stage (spoiling) by placing them in the refrigerator. This will preserve them for several more days, though it can slightly affect texture.

Frequently Asked Questions

Here are answers to some of the most common questions about ripening tomatoes indoors.

Can you ripen tomatoes that are completely green?

Yes, but only if they are “mature green.” This means they have reached their full size and have a glossy, whitish-green skin. Very small, dark green tomatoes may never ripen properly.

How long does it take for tomatoes to ripen inside?

With a paper bag and a ripe banana, tomatoes often ripen in 3-5 days. Using a box alone or a windowsill can take 1-2 weeks, depending on temperature and their starting point.

Why are my indoor-ripened tomatoes not as flavorful?

Flavor development is tied to sugars and acids created while the tomato is still on the vine. Indoor ripening finishes the process but can’t create flavor that wasn’t started. Always start with the healthiest, most mature green tomatoes you have for the best taste.

Should I remove the stems?

It’s best to leave the stems attached. Removing them creates a small wound where mold and bacteria can enter. Place the tomatoes stem-side down to prevent the stem from puncturing other fruit.

What if a tomato starts to rot?

Remove it from the container immediately. Check the tomatoes it was touching for any soft spots and wipe out the container with a vinegar solution to kill any mold spores before continuing.

Using these quick indoor ripening methods, you can enjoy garden-fresh tomato flavor long after your outdoor plants have finished for the season. The key is patience, the right container, and a little help from a ripe banana. With a small amount of effort, you’ll have perfect red tomatoes ready for your next salad or sauce.