Good afternoon all! I grew some san marzano plants this year. Plants were extremely healthy. Managed to control the infamous blossom end rot that these varieties typically suffer, but my tomatoes are ripening odd. The sides are ripening last, if at all. I noticed that someone I know picked up a few bushels from a farm and some looked the same, so it may be an issue with this type of tomato. Problem is if I wait for the sides to turn red, the rest if overripe and squishy. I don't mind too much since I use for sauce but some have black rot inside at this point so I have to throw them out. Do I just cut out the yellow part, use the ripe part and call it a day? Any assistance would be appreciated.

I grew Roma in the same plot and haven't had the same issue - despite blight being a real pain in my butt. Managed with some fungicide.

Unimproved San Marzano and several of its hybrids are very weather/soil specific plants. To cut a long story short San Marzano are extremely fussy plants I wouldn't personally grow again, especially given the ready availability of enormously improved hybrids such as Dunne and Roma.

To get back to us, what you are seeing two different problems.

The rot inside the berries is another form of blossom end rot. These are plants that require a ton of slacked lime in the soil: calcium foliar fertilizers work well but the whole thing may turn into an expensive chore quick.
The other problem is called uneven ripening and 90% of time is a combination of environmental and genetic factors. Read: San Marzano requires more hours of direct sunlight than you are getting and/or a different pattern of day-night temperature fluctuations.

Nothing you can do right now, just plant something more suited to your local growing conditions next year.

Thank you for the response. I wish I researched SM before I grew it. Many have issues with it -- as you said, it is a fussy. Probably why I can't find any at any local farms. I will stick with Roma's next year.

What about Amish Paste? I was consider Roma for my determinate variety and AP for my indeterminate?

I've never grown Amish Paste, but if the official story is to be believed it's considerably older than San Marzano (introduced in 1870 vs 1926) and most likely doesn't share all its many genetic/environmental quirks.

Regarding determinate vs indeterminate: I have never been able to grow a tomato without at very least a cane, unless I wanted them to grow as creeping vines. The only difference for me is indeterminate cultivars need to be "beheaded" to keep them in check while determinate cultivars struggle mightily all season long.

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Noticed my tomatoes suffer from puffiness -- very hollow. I'm assuming I made a huge mistake top dressing with a top soil w/fertilizer, when I already fertilized at transplant and after 30 days from transplant. I'm assuming the additional nitrogen messed them up. The first tomatoes that were forming before I did that were fine. All the ones forming after were hollow. I guess I learned my lesson.

Luckily If I cut out the green/yellow, they still make good sauce.

In the same plot of land, I have romas as well. About 1/3 of tomatoes are still green. They started ripening in early August. I know we had a stint of hot weather, so I'm assuming that's why a lot of green lingered into September, but now that the weather has broke, they are still green. I'm assuming I will lose a lot of harvest in a couple weeks at frost. SAD!

My first year gardening at this level -- 23 plants -- so mistakes were guaranteed, and have been learned from, but at least I managed to avoid a ton of blossom end rot on my SMs and kept my Roma foliage green w/o too much blight. Slight success for 2020.

I don't think the fertilizer has anything to do with it: excess nitrogen stimulates a lot of leafy growth to the detriment of flowers and berries. But I have never seen it happen to vegetable, only ornametals.
There's actually a strain of San Marzano tomato called "Scatolone" (big box) in Italy which are specifically bred to be very "hollow" and almost as dry as bell peppers to be used in some dishes: the genetics of San Marzano are pretty weird and to make matters worse it seems the original strain introduced in 1926 went extinct in the early 60's as it was rapidly replaced by improved hybrids. I can only guess you are seeing some of the usual genetic weirdness associated with San Marzano, especially those coming from open pollinated seeds.

Here's a tip to force ripening before the first frosts: leave all plants on their supports and strip away all the leaves and the smallest berries. You should get your tomatos to ripen in 10 days at most (unless the weather turns really cold) and it will also slow down the spread of blights.