Gardeners usually have two options when it comes to picking tomatoes. You can either wait until the fruits are fully ripe before you pick them., or you can pick your tomatoes just before they are ripe. You might get better flavor if you wait to pick your tomatoes, but harvesting the fruits before they are completely ripe gives you more control over the process. It also reduces the risk for damage to the fruits.
Some people argue that letting tomatoes fully ripen before picking them leads to the best tasting fruit. There's a scientific reason for this, argues Tomato Dirt. If you pick a tomato before it's fully ripe, you cut off its supply of oxygen from the main plant.
The not-quite-ripe fruit will continue to ripen after being picked. But, the sugars that develop in the tomato do not have the oxygen they need. Without a supply of oxygen, the sugars easily turn into decay-promoting compounds, such as sugar alcohols and ketones. The decaying sugars can negatively affect the taste of the tomato when it does finish ripening.
For that reason, many gardeners prefer to wait to pick tomatoes until they are fully ripe.
You can tell if a tomato is ripe partly based on feel and partly based on the way it looks. The above video, from About.com, walks you through the process of choosing a ripe tomato.
Once upon a time, home gardeners mainly grew red tomatoes. That made it easier to know when to pick a tomato, since all you had to do was wait for it to turn fully red.
Since many gardeners now grow tomatoes in a rainbow of colors, from yellow to red and from pink to green, it's particularly important to know what the final color of your tomatoes will be. Knowing that will keep you from picking them too early or from waiting for them to turn a hue they'll never be.
Usually, a tomato is ready to go when the color is even all over. For example, a red, ripe tomato will be red all over the fruit, not just on one side or not just on the bottom.
How the tomato feels can also help you determine if it's fully ripe or not. A ripe tomato won't be very firm to the touch. It also won't be too soft or squishy. Instead, it will most likely be somewhere between too firm and too soft. Give the tomato a very gentle squeeze. If it gives somewhat to pressure, it should be good to go.
Some gardeners argue that you should pick tomatoes before they become fully ripe. According to Aggie Horticulture, you can increase the size of your tomato harvest if you pick tomatoes before they are entirely ripe.
Harvesting the fruits before they are completely ripe tricks the tomato plant into thinking that it needs to produce more. Another argument in favor of harvesting the tomatoes before they are completely ripe is that doing so protects them from birds.
Birds are likely to go after fully ripe tomatoes and might get to them before you can pick the fruits. You can protect the fruits from birds by cover them with old, clean stockings or nylons. But for many gardeners, it's just easier to harvest the tomatoes a little early.
Here's one more reason to harvest tomatoes before they are fully ripe. Doing so reduces the risk of damage to the fruit. Some tomatoes, notably cherry tomatoes, are likely to crack or split when left on the plant for too long.
Cracks in the skin of the tomato make it more likely that the fruit will be exposed to mold or bacteria. The mold or bacteria can cause the fruit to rot quickly.
Picking tomatoes before they are fully ripe also gives the gardener greater control over the ripening process, according to K-State Research and Extension. Although many people think of tomatoes as sun-loving, heat-loving plants, the truth is that they get a little fussy when it's too hot out.
According to Modern Farmer, temperatures above 86 degrees Fahrenheit mess with the tomato ripening process. A green tomato won't turn red or fully ripen on the vine when it's too hot outside. If you live in an area that regularly sees 90 degree days (or hotter) in the midst of summer, your best option is to pick the tomatoes when still green and let them ripen indoors.
Tomatoes produce ethylene gas, which plays a big role in the ripening process. By the time a tomato has reached its full size and has an even green color, it has enough ethylene gas in its fruit to continue the ripening process on or off the vine.
Ethylene gas decreases the amount of chlorophyll in the fruit, so that the green color fades. The gas also increases the carotenoid pigments in tomatoes, which helps them turn red, yellow or orange.
Once you've picked an unripe tomato, you have some control over how quickly it finishes the ripening process. Storing the tomato in a warm place, such as on the counter in your kitchen, helps it ripen more quickly. Putting the tomato in a paper bag also speeds ripening.
Here's a great video about how to help your tomatoes ripen.
The bag traps the ethylene gas, so that the tomato ends up absorbing more of it. Some people put unripe tomatoes near ripening bananas to speed up the process. Like tomatoes, bananas produce ethylene gas. They have a tendency to speed up the ripening process of any fruits they sit near.
You can slow down the ripening process by putting the green tomatoes in a cooler area. According to Aggie Horticulture, tomatoes stored at 55 degrees Fahrenheit will finish ripening in 28 days Tomatoes stored at 70 degrees F will ripen in about 14 days.
Whether you wait for the fruits to fully ripen or you decide to harvest early, use a gentle hand when picking your tomatoes. If the fruit doesn't come off the vine easily, it's best to use a pair of garden shears to cut it away from the vine. You don't want to damage your tomatoes when picking them, putting all your hard work to waste.