QUESTION: Should I remove yellow leaves from tomato plants?
ANSWER: As your tomato plants grow to the height of 12-18 inches, you may observe that the leaves below the first flower cluster are turning yellow or necrotic. For all tomato cultivars, you can prune out any dead or senescent foliage as long it is beneath this first flower cluster.
With determinate types of tomatoes, there is no benefit in removing dead or dying leaves, or “suckers,” which develop higher on the plant.
You may choose to remove some of the “suckers” which develop at the junction where a branch joins the main stem on determinate tomatoes provided they do not exceed the height of the first flower set. For indeterminate tomatoes, all suckers may be removed as long as their size does not mean that leaving them would result in significant harm to your plant.
Indeterminate types of tomatoes may benefit from more aggressive pruning and removing dead or yellowing leaves at any height compared to determinate varieties.
This is because with determinate tomato varieties, they will only bloom once and bear fruit, meaning that there is a fixed quantity of potential tomatoes that can’t be altered much through pruning. In contrast, indeterminate varieties bloom multiple times during the season, so they are able to reap the benefits of good pruning.