Seed circles, pass-the-parcels, the Heritage Seed Library and seed swaps mean lots of interesting (and free!) seeds come my way to try out on the plots. I still buy new seeds, and in the cold dark of winter I can spend days thinking through plans for growing and reading through seed catalogues.

There are lots of places selling new, unusual, open-pollinated varieties, and these are some of my favourites:

Real Seeds A brilliant, small company that started me thinking about seed-saving and inspired me to see if I could start a seed circle of my own. They have a minimum order level, but that’s not hard. They offer help and advice too, which is great. I go here first for seeds.
Baker Creek (US site) The variety stocked here is jaw-dropping. Their packets are generously stuffed with seeds, postage to the UK is reasonable and the winter squash section quite frankly makes me dribble.
A Bean Collector’s Window (US site) Possibly the biggest collection of bean varieties under the sun. How he can grow so many is beyond me, but I’m so glad he does!
Beans and Herbs Holds all the main vegetable seeds, but has a great heirloom bean selection, most of which are hard to find. 
Bobby Seeds A German site specialising in squashes and pumpkins – other seeds are available.
Chileman OK not a seed merchant, but this site has a massive amount of information about chilli varieties. It also hosts a database of amateur growers and a seed exchange, which can be really useful too.
KCB Samen Swiss site also specialising solely in squashes and pumpkins. If it’s not listed in Baker Creek, it might well be listed here. But the company doesn’t ship between July and December.
Otter Farm Shop Mark Diacono’s smallholding, selling a nice range of unusual seeds.
Plant World Seeds UK company with a wide variety of seeds – tomatoes and squash particularly.
Seeds of Italy Not always the cheapest seeds, but they are generous packets and sell lots of Italian staples like leaf chicory, which are, as I live with an Italian, absolutely essential.
Thomas Etty Esq Carries a great range of heritage and unusual seeds, with generous packets and I like the slightly antiquated language. The catalogue is usually without pictures, and hyperlinks to show up on searches, which is a bit of a shame.
Victoriana Nursery Has a great range of seeds and plants, but is particularly good for chillies, and runs an annual chilli festival which is well worth a visit.

These places have more of the staples, and I like ’em:
Moles Seeds Really good value – huge packets of seed. Might need a smallholding to make the best use of them, or split them with friends.
Seed Parade Nice selection of seeds at good prices.

Plus, there’s the annual Wyevale 50p seed sale, which has my fingers drumming impatiently till it arrives towards the end of August each year.

Which are yours?