Speeding Up Ripening of Tomatoes and Peppers?

Help for the Home Gardener from the Contra Costa Master Gardener Help Desk

Client's Question and Problem:

Client left a message on the Help Desk telephone. Client is growing two tomato plants and some pepper plants in containers. While they have produced fruit, but most of it is still very green (as of early September). You wanted to know if there was something you could do to speed up the ripening process. CCMG Help Desk responded by email.

CCMG Help Desk's Response:
I'm writing to respond to the questions that you left in your Help Desk phone message. I understand that you are growing two tomato plants in containers as well as some peppers. You mentioned that the tomatoes have produced fruit, but most of it is still very green (as of early September). You asked whether there is something you can do to speed up the ripening process.

You probably won't be able to speed up the ripening of the tomatoes. The timing of getting ripe tomatoes depends both on when you started the tomatoes and on the variety you are growing. In my own garden, I planted eight different heirloom varieties this year. Two of them are in pots. I planted seedlings from four inch pots in early April. Most of the tomato varieties starting giving me quite a few ripe tomatoes by late July. However, one of them only produced an occasional ripe tomato until about a week ago, when I started being able to harvest three or four ripe tomatoes per day. The two tomatoes I have growing in containers are likewise producing ripe tomatoes at different rates. One has produced many ripe tomatoes and only a few green ones remain on the plant currently. The other was much slower to start producing ripe tomatoes. I've picked quite a few of them, but it still has lots of green tomatoes which I know will continue to ripen over time.

So my advice is just continue to be patient. For earlier tomatoes next year, you could pick a variety that produces early fruit. Or, if the weather cooperates, you might be able to plant your containers somewhat earlier next year. (I generally wait for night time temperatures to regularly reach 50 or above before planting. That target temperature occurred somewhat earlier this year than it does in many years.)

As for your question as to why your pepper is producing green peppers when the variety is supposed to be red, again the answer is that you'll just need to be patient and wait a while longer. All pepper varieties start as green peppers. With time, varieties that produce other colors will begin to ripen and change color. It sometimes takes several weeks after the green peppers have developed to their full size before you will start seeing a color change.

Both peppers and tomatoes can easily be sunburned. The sunburned area turns a light brownish color. It's still fine to eat the fruits, but you generally have to cut out the sunburn. To prevent your green tomatoes and peppers from getting sunburned, try to be sure that the developing fruit has some leaf cover. If not, you can also erect some type of sunshade to keep the sun from scorching the fruit.

Finally, as we approach fall and cooler temperatures, you may find that the ripening process slows. I generally leave my tomatoes in the garden if they still have green fruit until the night-time temperatures start to dip into the 40's. Tomatoes are quire cold sensitive so the plants will start dying when the weather cools. At that point, I harvest all the green tomatoes and put them on my kitchen counter. They will continue to ripen there. The fruit that ripens that way isn't as wonderful as a vine-ripened fruit, but it's still better than what you can buy in the grocery store. Unfortunately, peppers won't change color after you harvest them, but the green colored peppers can be just as tasty as those that have taken on their ripe color.

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A post script...

I hadn't realized from your phone message that the main question you have is “Why has the ripening of the tomatoes slowed down so much from what it was in prior years?” Thanks for clarifying.

Here are a couple of possible causes.

• A key resource that tomatoes need for ripening is plenty of leaf surface for photosynthesis. Often by late summer, some of the leaves on the tomato have started to dry up and wither and are no longer helping to nourish the plant. The plant is less vigorous than it was earlier in the season so it takes longer for the green tomatoes to ripen.
• High temperatures are also a major cause of slow ripening. The tomato plant produces several compounds that are needed for tomato ripening. When the air temperature rises above 85 degrees, tomatoes stop making carotene and lycopene pigments, two of the most important components in the ripening process. We have had some recent hot weather spells which are probably affecting your tomatoes in this manner.
• Finally, soil temperatures are also important. For optimal growth, tomatoes need soil temperatures that are less than 80 degrees. Hot air temperatures raise the soil temperature. Containers may be particularly vulnerable to soil temperature rise if they sit in the hot afternoon sun. Mulching can help keep soil temperatures lower. Also, if your tomatoes are hit by afternoon sunshine, you might consider erecting some shade barriers to keep the sun off the containers.

If you've run out of patience with slow ripening tomatoes, one thing you can do to speed up ripening is to remove some of the green tomatoes. Then the tomato plant can put all its energy into ripening the tomatoes that remain on the plant. You can ripen the green tomatoes you remove on your kitchen counter. As I responded earlier, they won't be as yummy as the ones that ripen on the vine, but they're still better than store bought tomatoes.

As a final caution, don't be tempted to fertilize the tomato plant thinking it will speed up production. Fertilizing now will probably just cause the tomato to go into a vegetative growth mode that is too late in the season to be helpful.

Hope the above explanations clarify what is occurring. You're welcome to contact us with any additional questions.

Contra Costa Master Gardeners Help Desk 

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Editor's Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523.

We can also be reached via telephone:  (925) 646-6586, email: ccmg@ucanr.edu, and we are on the web at http://ccmg.ucanr.edu/

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