Seville oranges for marmalade - how important is freshness? We're currently (in January) in the brief season for seville oranges which means it's marmalade making time.

I acquired some sevilles as soon as they appeared in the shops here a week ago. However things have suddenly gone crazy at work and I'm not going to have time to have a marmalade making session now for a week or two.

How well will my sevilles last if I wait that time before making my marmalade?

Are greengrocers and supermarkets getting sevilles in pretty much daily? In which case I think I'll just go out again and buy more when I have a bit more time (so long as I do it before the season closes). Or does Spain just dump one giant load of the fruit on us at the beginning of the season?

I guess it's this latter part of the question which is most intriguing (since I know I can always freeze the sevilles I already have) since seville oranges are one of those very few products which are still truly seasonal. How does the supply chain work, and why are they so seasonal when so many other kinds of produce are nowadays available nearly all the year round? 

Finally, what are the rough start and end dates for the seville orange season in the UK? I feel like it's the middle two weeks in January, but I haven't really checked up on that.
I'm presuming that your'e British because (a) You want to make marmalade (b) your nickname is 'tea drinker'. am i right?

Anyway, those bitter oranges are grown not only in Spain but in other parts of the Mediterranean as well, but their season i relatively short - so if i were you i would keep my eyes open for nice ripe ones and buy them - you can keep them cooled for at least a month in your fridge if they are in good condition in the time of their purchase.

Tip #1: try to buy oranges that weren't waxed.

Tip #2: if you can get Satsuma Citruses, they will do a good job as replacements. The result might be a little more sour though.