Prolonging Your Tomato Growing Season

Over the Garden FenceSeptember 11, 2023 – By UC Master Gardener of Mariposa County – Helen Willoughby-Peck – Red, yellow, green, orange, brown, purple, and even white, the quintessential tasty treats of summer will soon stop producing. Cooler weather and shorter days signal the end of our tomato growing season and your plants will begin to decline. Tomato lovers will soon be forced to consider tasteless and characterless supermarket tomatoes.

But wait! Here are a few ways to extend your home-grown tomato season.

Bring plants inside: If you planted your tomatoes in pots bring them inside. Or try digging out a plant or two, potting them up and sharing a sunny window in your cozy home. Some varieties will continue to produce for a time despite the shorter days.

Harvest early: Tomatoes are very sensitive to frost. When frost is predicted, you may want to harvest all fruit that are in the mature green stage of ripening. Fruit harvested at this stage will still ripen, although not with the same flavor as fruit harvested with some color. Place fruit in a single layer in a warm, dark location with some air movement. Tomatoes and other fruit do not need light to ripen. Store the fruit where the temperature does not go below 55 degrees. Or, as an alternative, dig up your tomato plants, remove as much dirt as possible from the roots and hang the plants upside down in a garage or shed. Pick the fruit as it ripens.

Irrigate before a frost: A moist soil can hold four times more heat than a dry soil. It will conduct heat to the soil surface faster than a dry soil. Studies have shown that air temperature above a wet soil was 5 degrees higher than that above a dry soil. Thus, plants should be well watered the evening before a frost.

Cover your plants: Covering your plants can give them frost protection. The covers can be placed right over the plants or can be supported on stakes. Any material can be used to cover your plants however woven fabrics are better insulators then plastics or paper.

Another covering method is to build a vertical cloche (a transparent covering for outdoor plants) using stakes or wire fencing around an individual tomato plant. Wrap plastic or sheeting around the support, leaving the top open during warmer days but tie the top closed when it is cold.

Choose varieties bred for cooler weather: Next year remember to plant a few varieties that are recommended for cooler areas and can produce well into the fall months. Red October can be harvested in October and has a shelf life of 3-4 weeks after harvest. Champion and Siberian are both varieties that produce well into the frost season. An online search will help you identify other varieties from colder climates.

For assistance, contact our Helpline at (209) 966-7078 or at [email protected]. We are currently unable to take samples or meet with you in person but welcome pictures.

The U.C. Master Gardener Helpline is staffed; Tuesdays from 9:00 A.M. – 12:00 P.M. and Thursdays from 2:00 P.M. – 5:00 P.M. 
Clients may bring samples to the Agricultural Extension Office located at the Mariposa Fairgrounds, but the Master Gardener office is not open to the public. We will not be doing home visits this year due to UCANR restrictions.

Helpline Serving Mariposa County, including Greeley Hill, Coulterville, and Don Pedro
Please contact the helpline, or leave a message by phone at: (209) 966-7078
By email (send photos and questions for researched answers) to: [email protected] 

For further gardening information and event announcements, please visit: UCMG website: https://cemariposa.ucanr.edu/Master_Gardener
Follow us on Facebook at: https://www.facebook.com/mariposamastergardeners 

Master Gardener Office Location:
UC Cooperative Extension Office,
5009 Fairgrounds Road
Mariposa, CA 95338 

Phone: (209) 966-2417
Email: [email protected]
Website: http://cemariposa.ucanr.edu/Master_Gardener

Visit the YouTube channel at UCCE Mariposa.

Listen to us on the radio at KRYZ 98.5 Mariposa on Wednesdays at 2:00 P.M. and Saturdays at 5:00 P.M.

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