What to do with those old and dying tomato plants?

The days are getting shorter, the smell of fall is in the air, and the last few tomatoes are hanging on, struggling to ripen on the vines. As we near the end of the growing season, it is time to start talking garden cleanup, and what to do with all that dead and dying plant material. The good news is that most of it can go straight into the nice new compost bin beside the shed – it will break down over the winter and make a nutritious addition to our beds in the spring. However, there is one major exception to this – tomato plants! When it comes time to take out your tomato plants and any unripe or diseased fruits, we will require you to pack those up and take them home with you for disposal in your household garbage or green bin.

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There are few good reasons to keep those tomato plants out of our compost bin:

Tomato plants are prone to diseases caused by fungi, bacteria and molds, from anthracnose (those black spots on the fruit) to early blight, fusarium wilt, and bacterial canker. Most of these diseases will overwinter on dead vines, leaves and fruit. If we put diseased tomato plants in the compost, the pile will need to reach a consistent internal temperature of over 130°F for several weeks to kill off these disease organisms – something our compost pile is highly unlikely to manage! If these organisms are present in the compost next spring, it can spread disease all around the garden and infect next year’s tomato crop, starting early in the season.

Tomato fruits that are put in the compost can result in viable tomato seeds that sprout in the spring. Free tomato plants next year may seem like a great thing. However, if the seeds are from a hybrid tomato, chances are good that the resulting vines will be sterile and will produce no fruit. If unwanted seedlings come up next year it is easy to simply dig them under or pull them out. However, if those composted tomatoes were affected by anthracnose, it will be present in the compost, and will transmit to the next year’s crop.

Tomato vines are tough and don’t break down easily. If thrown in the compost without being chopped up into small pieces, they can result in stringy compost that is hard to handle and just plain annoying.


We therefore recommend that you carefully inspect your plants when you are doing garden clean-up, and bring a garbage bag to take home your tomato plants, and any other plants that don’t look healthy. And please don’t put weeds in the compost, especially if they have flowers or seed pods – the compost pile will not get hot enough to kill off weed seeds either, and we don’t want to spread these around the garden plots! We also recommend that you bring a pair of clippers or scissors to cut up any large stalks, long branches and vines before you put them in the compost. It will help the composting process and make our compost better.

There are a few other plants that can be prone to disease, and that I tend to keep out of my compost at home, particularly if I notice signs of disease. These plants include peppers, which are from the same family as tomatoes and are prone to many of the same diseases, as well as beans. I usually put this kind of material in my green bin – the industrial composting process hits temperatures high enough to kill off diseases and weed seeds.

A tip for next year: one way to keep good air circulation around your tomato plants and help reduce the chances of certain mold and fungal diseases is to pinch off some or most of the suckers that grow from the points between the leaves and the main stem when they start to appear, and to pinch off lower leaves once the fruit start to grow. Reducing the density of the foliage will result in lowered risk of certain diseases which can thrive in a high-moisture environment. For a deeper exploration of why, how and when to sucker your tomato plants, I recommend this site: https://savvygardening.com/tomato-plant-suckers/