A: There are two schools of thought about that, and I’m going to have to land on the side of fresh tomato starts. I’ve done it both ways. Healthy plants of indeterminate types can be made to fruit again for fall. Greenhouse tomato growers keep individual plants productive for a very long time – maintaining optimum temperatures and conditions year ’round. There’s just one problem – we don’t live in optimum temperature conditions.
I’ve tried this myself for years, just replacing determinate-type tomatoes and any tomato plants which look stressed in early July, leaving all my best looking plants alone. I did get some decent production on the older plants, but it’s far too easy to end up with heat stressed older tomato plants by the time temperatures come back around to productive ranges, and by the time it happens, it’s too late to plant young plants to replace them. Young tomato starts are much more forgiving of the heat, given adequate water, and you’ll generally find fewer pest and disease problems present on your fall crop of tomatoes if you simply make a clean sweep of your older tomato plants and start fresh.
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