Every year I grow sweet peas, mainly for cut flowers but also because for a small footprint you get loads of colour and scent. I grow them in a 40cm square container that has a good depth and volume of growing media. I always try to use a container compost mix that has water retention crystals included, as sweet peas can be very thirsty even on a warm summers day.
They prefer full sun to get the best amount of quality flowers but any spot that isn't in deep shade is suitable. Make sure you keep them well supported with canes and tie the shoots in with string or special wire rings made for the job. The worst task though is to then remove any of the tendrils that grow to support these climbers in their natural habitat. If you don't remove them, they tend to cling and constrict any flowering shoots making them unsuitable for cutting.
The varieties I have grown this year are Cupani and Suttons Early Fragrance Mixed. The summer weather has not been kind to them and as you can see from the photograph, growth has been slow and flowering has only just started.
Though an old fashioned favourite, sweet peas are great for the small garden. The colours vary from strong primary colours to pastel tones, so make an impact were ever you put them.