Most likely there was 2 seeds stuck together. Difficult to see and happens often. Just leave one of them if you aren't going to separate and transplant the extras.

Dave

Yes, it was probably two seeds stuck together. Here is a trick way to separate them if you want to save both plants. Wait until they get big enough to handle. Then dip the whole root ball in a container of water and jiggle it up and down and swish it around until all the dirt comes off. Then you will just have roots and you can easily separate them. Immediately replant them and really saturate the soil, I dip the whole container in water.

DUH! When I look at a handful of seeds under my 10x binocular microscope, there are a few that are 2 seeds stuck together. Thanks digdirt!

I agree it's probably the result of two seeds being there but if it isn't, and they are fused stems, two fused together, then they're called fasciated stems. It happens from time to time but would not be expected to happen with all the seeds you sowed for San Marzano as you described above.

Carolyn

californian, I'd like to save the little guys but they're planted in a hole in the bottom of a 5-gallon paint bucket, my first experiment with growing tomatoes upside-down. So there's really no way to mess with them other than to select the lucky(?) one who survives to be hung inverted from my southern-exposure garage rafter tails.

mikemr
yeah whenever I see a seed that looks a little fatter it is usually 2 stuck together as mentioned above.
I take a coin envelope with it open and push the flap between the 2 seeds they separate easily that way - oh on a rimmed paper plate so it doesn't fly off the table
Dennis

Last spring the local garden centre sold sweet millions in clumps of 10-12. They were planted in the center of a 3" pot. I made a slurry of the dirt and they separated easily. I lost one of two of the smaller ones and still had 10 plants -- $0.25 each :)