On mine too - though there are buds at last. I had completely given up hope!

Could it be a short variety?

Some are from last year's seeds and they were much longer then. Don't think the others are a short variety - daughter sent me a photo of hers in a vase and they have reasonable length stems.

Growing conditions haven't been ideal in most places this year, some places have had more rain than usual, others not enough, and early in the season there were alternating hot and cold spells. Perhaps they're doing the best they can in the conditions available. It would be interesting to save some seeds and see how they go next year.

Many years ago (and I mean many) an old gentleman (who won prizes for his sweet peas) told me how to get more flowers and longer stems on my sweet peas, he said take off most of the tendrils that they use to climb and hold tight with and you will get lots more flowers and longer stems, it worked for me I won 2nd prize to him in a competition in the village I used to live in. LOL and in those days the perfume on them was amazing (not had any like that since)

I'll try that next year! My daughter has just sent me yet another photo of a vase full of glorious, long-stemmed, many coloured sweetpeas. I am green with envy - I planted the same seeds in my pots as I did in hers. Though granted mine went in about 3 weeks later so I guess there is hope yet.....