They will probably continue to grow but won't be as big as they would be if they had their own pot or more so if they were in the ground. It also depends on the type of sunflower you planted. Some want to grow very very tall so a 4 inch pot is just not enough room for those.

My best luck with sunflowers (any type) is to direct sow the seed where you want the flower to grow. Seems almost too simple but this has worked for me the best. My transplants always suffer and usually don't make it.

Good luck, Sunflowers are so beautiful.

I am sorry that I was not clear.

These sunflowers were started in 4" pots, then planted in the ground. They are growing tall, but stem to stem.

I have munchers, earwigs and probably others, despite diligent beer trapping. Sunflowers sown directly and those transplanted small were munched to death. Bigger transplants survive.

I have no advice, but I am your gardening compatriot... 37 and planted my first sunflowers ever this spring. They just sprouted last weekend. Go sunflowers!

:) they'll be fine... mom raised me to plant them Russian style- three in a hole. so 'twins' should be downright roomy for them. depending on the species, they might lose a foot of height if the ground is really rotten-

but that just means the flowers will be closer to your face :)