enter image description hereShould I trim my determinate heirloom tomato plant of yellowing leaves and branches?

I did a lot of research on how to trim, but all I could find was the general advice of “determinate plants don’t need trimming.” Does this mean I SHOULD NOT trim my determinate tomato plant at all, and leave yellow and dry leaves on the plant?

If not, and I should trim, how? Should I cut off just the leaves that are yellow? If an entire branch is yellow and drying out, should I cut off that branch? The entire circled branch 1 is yellow; the entire circled branch 2 is also yellow, though no leaves and very short; circled branch 3 looks like it will all go yellow but currently it’s just some of the leaves.

Background: It‘s a German Johnson variety that I transplanted from a nursery into its current pot almost two months ago. I water with filtered water; I fertilize with Fox Farms Grow Big liquid plant food 6-4-4 every two weeks; the soil is covered with organic mulch.

Just noticed that one of the tomatoes (pictures) looks like it might be getting blossom end rot. I have added an eggshell to the soil roughly once per week for the last month. Should I be doing more and/or something else?

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  • A general note on trimming tomatoes. They are fickle little things when it comes to pathogens, I have found. Make sure to use a sharp pair of pruning shears and dip them in rubbing alcohol with each cut to prevent spreading any spores, etc. If you don't have mulch on top of your soil, that can prevent splashing of spores as well. I use dried grass clippings. If placed on top while moist, keep them away from the stems or they will heat up.
    – Evil Elf
    Nov 24, 2020 at 10:22

2 Answers 2


Trimming those branches is more of a personal preference than something you should or shouldn't do. If it was my tomato plant, I would trim branches 1 and 2 right now, and wait until branch 3 is fully yellow to trim it. To me, it looks better and it prevents diseases from spreading.

To treat the blossom end rot, I say that you should pick up a bottle of Cal-Mag. This is because the eggshells take a while to break down and won't give immediate relief. You could also react the eggshells with muriatic acid or vinegar. Just ensure that you don't use too much acid when dissolving the eggshells so you don't hurt the plant roots.

Other than that, your tomato plants look great. Keep up the good work!


I would definitely trim the yellowing branches as you want to have nice airflow through the plants to make sure you don't develop fungus. Keep in mind its a balance (art vs. science), as the leaves are needed for photosynthesis which feeds the plant so you don't want to take too much off. In your case, the yellowing leaves are most likely safe to remove because I only see a few. I believe the guidance you were reading online in regards to pruning determinate tomatoes is referring to pruning suckers as opposed to branches. Typically on a determinate variety you don't want to prune suckers as you want the plant to push out as much fruit as possible.

On the blossom end rot issue, adding egg shells are great but remember that the calcium isn't readily available to the plant until the egg shells are broken down. I'd use something that is fast-acting like a liquid calcium. You can use this as a foliar spray or feed the roots directly both are effective. Also be mindful of how consistent you are with watering and consider mulching with straw or wood chips to help maintain an consistent moisture level in the soil--this can also help with your blossom end rot.

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