5 Tips For End Of Season Tomato Plant Care

A gardener holds ripped up tomato plants in a greenhouse
(Image credit: Helin Loik-Tomson)

When the growing season is waning, time is running out for crops like tomatoes that are still producing. Some of the fruit on the end of season tomato plants is almost ripe, while the rest is still green. Should you pull all the end of season tomatoes and, if so, then what? Many of them are still unripe. If you want to get the most out of your end of season tomato plants, read on to learn what to do with tomato plants before the first big frost.

When is the End of Tomato Season?

The beginning of tomato season varies depending upon your location. This means that those in the warmer climates of the South may be planting tomatoes as early as January, and harvesting by April, May or June. In cooler climates those tomatoes won’t get into the ground until May or even June, and will be harvested mid-summer to early fall.

Tomatoes in cooler climates may still have plenty of fruit, but an imminent frost shuts down production and ripening.

What to Do with Tomato Plants at the End of the Season

Tomato plants are warm weather tender perennials that thrive in full sun with temperatures of 70-75 F (21-24 C). As temperatures cool heading into fall, the ripening process slows -- so much so that unripe fruit often remains on the plant as the first frost arrives.

So, what can you do with your tomato plants as autumn approaches in order to harvest the most tomatoes possible? Keep an eye on the calendar and weather forecast, and follow these five tips.

1. Harvest the Last Tomatoes (Even the Green Ones)

Fresh ripe tomatoes off the vine are divine, but toward the end of the growing season it becomes patently obvious that this good thing is coming to a rapid end. Up to a point, you can cover the tomatoes overnight when temperatures drop, but as it gets colder you will have to become more drastic in your approach. Tomatoes cease to thrive when temperatures hit about 50 F (10 C), and the plants will not survive when they get below 35 F (2 C).

To hasten outdoor ripening, cut off any blooms or small fruit. This will be a signal to the plant to put all its energy into ripening the rest of the fruit.

When temperatures dip and frost is in the forecast, you should immediately harvest all ripe tomatoes, but don’t stop there. Harvest all the green tomatoes, too. Why? There are two reasons. First, you can fry up some succulent green tomatoes, can a green tomato relish or use them as a fresh twist on a salsa. Or, you can try to ripen them.

Some tomato varieties do better than others when forced to ripen indoors, but nothing is lost if you want to give it a try. Some gardeners pull the entire plant from the soil and hang it upside down in a dark cool area like a basement or garage, while others remove the fruit and then allow it to ripen. Either way, do not wash the tomatoes!

You can place the green tomatoes in a layer in a box for ripening. Some people individually wrap each piece of fruit, but that isn’t necessary. Ethylene gas is the ripening hormone given off by the fruit, and you can speed up this process by harnessing the gas. Simply place the unripe tomatoes in a closed paper bag or covered container, and add an apple. Keep a close eye on the ripening process and remove the fruit as it ripens. Green tomatoes ripen in about 2 weeks at 65-75 F (18-24 C) or 3-4 weeks at 55 F (13 C)

2. Cut Back Tomato Plants

End of season pruning is another way to extend your tomato harvest. There are a few reasons for pruning back tomato plants. Pruning improves airflow, thus thwarting some diseases. It can help produce larger fruit, and it can speed ripening. But only prune indeterminate tomatoes. Pruning determinate varieties will reduce production.

This was mentioned above briefly, but again, removing or pruning small blooms or fruit will act as a signal to the plant to devote all its energy to ripening the remaining fruit. Cut back on watering and withhold fertilizer at this time, as well.

3. Discard Tomato Plants

You will know when your tomato plants are done for the season. They’ll stop producing new foliage and fruit and will begin to look peaked. You can pull the entire plant out, roots and all, or cut them at the base and allow the roots to decompose. But before you make a decision, check the plants carefully for any signs of disease.

4. Watch Out for Disease

If you’ve noticed any signs of disease on your tomato plants, it may not be a good idea to allow any part of them to decompose in the garden. Some diseases are able to overwinter and infect the following year's plantings.

Spores that spread fungal disease are often left behind, but also any residual debris may be infected or infested with pest eggs that will overwinter. If in doubt, it’s a good idea to remove the entirety of the plant and rake up any remaining debris and dispose of it.

The compost pile isn’t a great place for infested plant material unless your pile gets really hot. The best bet is to burn it, but that isn’t allowed in many communities, nor is it a good idea when the weather is tinder dry as it has been in many regions lately. Another effective management tool to combat the spread of disease is to practice crop rotation.

5. Save Seeds for Next Year

If you want to save tomato seeds, remember that hybrids do not grow true to type, meaning they will likely not reflect the parent plant. If you have open-pollinated or heirloom varieties of tomato, saving seeds is a fun and resourceful, albeit messy idea.

To save seeds, cut open the tomato and squeeze out the seeds. These seeds are covered in a protective gel that must be removed. The easiest way is to soak the seeds in a jar or water-1/3rd seed to 2/3rds water. Stir and allow it to ferment.

Mold will grow on the seeds. This mold will break down the gel and release the seeds to sink to the bottom. Drain the mixture into a colander and rinse the seeds with water. Spread them out onto a paper towel to dry for a couple of weeks then package them into labeled envelopes.

Can You Winterize Tomato Plants?

There are several things that can be done to promote tomato growth during the winter months. How long these methods will aid in keeping your plants alive depends on where you live and the weather.

You can wrap your plants in a tarp, old sheets or burlap to get them through chilly nights. Remove the coverings during the day. Tomato plants can also be protected in a cold frame, tunnel or, of course, a greenhouse.

You may also bring your tomato plants indoors to grow. They will need plenty of light, more than even a window with southern exposure can provide in the winter. Ideally, provide them with supplemental light in the form of LED lights that should be run for 18-20 hours per day.

Beware of pests clinging to tomato plants that have been grown outside and are then brought indoors. Of course, without insects there will be no pollinators so, in the event your plant flowers, it will be up to you to hand-pollinate the tomato blossoms using a small, delicate brush and going from the male stamen to the female stigma.

The best type of tomatoes to attempt growing indoors are determinate types, such as dwarf or micro dwarf varieties.

You can also keep tomatoes alive indoors as stem cuttings or in bare root dormancy, kept in a cool basement, cellar or garage. The benefit of bare root dormancy removes the need for sowing seeds and results in an earlier harvest.

Amy Grant

Amy Grant has been gardening for 30 years and writing for 15. A professional chef and caterer, Amy's area of expertise is culinary gardening.