Caroline,
Grow singles , better for the bees and other flying insects, start with Bishop of Llandaff and maybe Magenta Star for colour, after that go for your own from seed from those plants. Dinner plates are vast, over heavy heads and repositories of earwigs and caterpillars, never mind the grazing slugs. Single flowers open in a few days, but the complex varieties take much longer to mature a flower and if your growing season is short you really need speed.
It takes about three years to grow good tubers from seeds and get a full sized plant without blasting them with a steroid mix. I start many from seed , with about 100% success and it is cheap as chips. Grow from seed, drop the seedlings into 3inch pots in year one and let them form their first tubers. They die down in winter and bring the pots inside and leave them somewhere peaceful I leave them in their pots as they tend to get drier if you clean them out and they shrivel like prunes. They will show you a leaf above the pot using the energy from the tuber in the following late spring. At that point you can water them.
In year two you can plant them out when the fear of frost has gone, they should be about 6 inches high by then, put bone meal or blood fish and bone in the hole for them water them in, put down slug pellets and make sure they get water every few days for a couple of weeks.You should get a full size plant that year, and you should put a stake with about eighteen inches above the ground showing. I tend to grow them on for another year in the raised beds before I put them in the garden, as I want to see what their form is for shape of bush and frequency and form of flower. I photograph and label the year two plant and if it is good, I don't let it flower much as I want the energy down into the tuber. If it is lovely but not for me, they make ideal gifts for other gardeners and for the garden society bring and buy each month or church charity drives. If it is a poor flower or shape it goes on the compost heap.
Inexpensive, with the opportunity of surprising blooms, and with an endless supply. Cheap, plentiful and a joy to grow. I will send you seeds if you want, although I don't know how that works on this forum.
All the best.
