No answer for you, Waddy, but just to add that mine are the same.:-// I guess that they are perhaps too crowded at the roots so not enough light getting down there. Mine were the same last year too and I swore then that they wouldn't be in pots this year! Famous last words!

I look forward to the replies!

I think Sweet peas like a deep root system. Whenever I try them in pots they always go yellow, and stunted, and have very few flowers.
In the old garden before I moved here, I always used to dig a trench and fill it with crumpled up newspaper, then plant them in the filled in soil on top of that. I had beautiful results like that. It works well for beans too. I don't do it in this garden - not enough room ... and I don't buy newspapers any more ;o)

Can be anything from type of compost used, over watering, under fertilising, size of pot. Probably all of them to some extent.
I'm growing sweet peas in containers this year. They have no signs of leaf problems. But i am using a 50 Litre container, 15" tall and 2 foot diameter !!!
And the compost is a mixture of garden topsoil and a peat based hanging basket compost, not a compost bought from the superstores.
As Hywel says, you really need them in the open garden that has been well dug to get the best results. You also need to start them off February at the latest....mine were started early December and overwintered in a cold frame before planting out early April.
Anyone buying seedlings in May in a 3" pot with 5 or 6 plants in it will never get decent blooms i'm afraid.

Anyway, I've done a little blog on them that may give you a few tips.

Graham.

Mine are the same and are planted in the ground, I cheated and bought them from a garden centre and planted them beginning of April.

Yes Scrumpygraham you are right about the size of pot. If you really want to grow them in a pot I think a very large one would be best :o)

What a lovely lot you are. Thank you so much for your responses. After reading your Blog, Graham I know I'll never be able to grow them like you do. Space etc dictate that they have to be either in pots or not at all. Nevertheless, I am going to try growing them from seed next time (Dec) and follow your instructions. The ones I have had in the past have been plants but bought from a reputable grower. I also will try deeper larger pots etc. Once again, thanks everyone!

Yes, space is a problem, but as a guide, as pictures can be deceptive, a space 4 foot long by 2 foot wide will get you 14 sweet peas in garden soil.
Must admit that even though I've planted out good plants, and dug the soil nicely, this year has been my worst ever year. I would normally have expected to have cut 400 sweet peas in the last 2 weeks. I haven't cut one. They've all suffered from bud drop, which is a climate thing that they grow out of, and it will be at least 10 more days before I get a decent vase as you can tell when they are growing out of it.
Friends and family, who take no care of the soil, and who rely on my "reject" left over plants to plant, have all been thrilled with the blooms they are cutting.

Nature is a wonderful thing:)

No sweet peas for me this year - but my lily leaves are certainly yellow.
They were perfect last year, in the same place & I had srumptious blooms with gorgeous perfume!
This year they look awful, though they have plenty of buds. I wonder if they will open out o.k.
I get a lot of bright scarlet red lily beatles on them & I'm afraid I take them off & give them the chop when I see them!! The numbers don't diminish tho'!! Blimmin' things!:(

Your sweet peas were going yellow due to lack of magnesium. Lack of nutrition in the soil. Feeding with Epsom salts solves that or a multi purpose feed. Overwatering can wash nutrients out of soil.

Crumbs, I had forgotten I had asked this question. Thanks for your answer GB. I've since solved the problem by feeding all my flowering potted plants with Tomato Feed, it seems to do the trick and I get great results all round. All I need now is some sun, don't suppose you know where I can purchase some of that do you?