Ripening Green Tomatoes Indoors

As mornings get chillier and the days get shorter, the demise of the summer garden is inevitable. As you harvest and prepare root crops, fruits, and winter squash for winter storage don't give up on the tomato.  The first frost does not need to end your tomato season!  Mature green tomatoes can be ripened indoors.

Some basic knowledge of you planting zone is helpful.  Do you know your average first frost day? The average first frost date is the average date at which a light freeze may occur.  There is a 50% chance it will occur before the date or after the date.  

Light Freeze:  29-32 degrees, tender plants killed

Moderate Freeze:  24-28,  widely destructive to most plants

Hard Freeze:  24 and colder with heavy damage

Look up your average spring and fall frost dates here:

Frost Dates

 In New Harmony the average first frost is October 9th.  So when October comes you need to watch the weather to be prepared to bring in mature green tomatoes before a freeze.  As daytime temperatures fall below 60 degrees, tomatoes are less likely to ripen on the vine. You can pick green tomatoes at this point and bring them indoors to ripen and remove your tomato plants from the garden or wait until a frost is predicted.

Picking Green Tomatoes

The best tomatoes for ripening indoors come from young plants still in their prime not older worn out plants that have been bearing all season.

Most gardeners have volunteer tomato plants that spring up in random places in the garden which are perfect for producing green tomatoes late in the season.  

Before a frost gather your mature green tomatoes.  Do not bother with the small whitish colored tomatoes, they will not ripen.  Pick only the mature green or riper tomatoes.  A mature green tomato is well developed, shiny, and medium or deep green.  Pick without stems. (Root Cellaring)

Most importantly pick before frost because frost damage can prevent proper ripening.  Interestingly, tomatoes that have some color are less sensitive to low temperatures.

Bring the tomatoes inside and sort them. Separate riper ones from green tomatoes.  

Keep some out to ripen right away.  Green tomatoes ripen quickly at room temperatures.  Spread them out single layer out of direct light in a room with temperature between 60-70 degrees.  A mature green tomato will ripen at room temperature in about 2 weeks.  If the tomatoes are already starting to turn then they will ripen faster.

You can wrap them individually in paper, place them in a box in the pantry,  or keep them in a drawer to protect them from direct light.

To keep some tomatoes to ripen later, store them at temperatures of  55- 60 degrees to keep them on hold.  Bring a few fruits at a time into warmer room temperatures to gradually ripen and enjoy throughout the fall. (Root Cellaring)

As tomatoes ripen they produce a gas called ethylene.  Bananas and apples also produce this gas. This gas actually promotes ripening.  

To quicken the ripening process you can place a few tomatoes in a brown paper bag with an apple or banana with green still on the tips.  

Another way to save some of those tomatoes for later in the season is to pull up the whole vine and hang it in a garage or shed.  The remaining leaves and stem will continue to nourish the fruit.  Be sure to hang where there is good air circulation and do not pull them up wet or they may just rot.

A great resource for preserving your harvest into winter is found in the book Root Cellaring by Mike and Nancy Bubel. 

Hopefully you will be able to continue enjoying garden fresh tomatoes an extra 4-6 weeks after a frost.