Firstly, as the flowers fade, remove the flower stem from the leaf structure, with scizzors if you like. As is the nature of most plants, it will want to produce babies, and you will have just removed the way in which it does so - seed.
It's next course of action will be to produce babies underground, ie. more bulbs!!!
In order to be successful, keep the plant fed and watered well into the summer, until the leaves naturally die down. Best to put your containers in the shade during this process.
Once the leaves have decayed, forget about the pots until it is time to protect them over winter. Wrap with bubble wrap or fleece - completely and totally, and place ON insulation.
Next year you will have at least twice as many flowers!!!

(Written by DerekF's friend)

In addition to Derek's advise I like to change the compost each year - it doesn't always happen, but I prefer to try and do this. If you do this allow the soil to dry out in summer, empty out the pots and collect the bulbs. I replant straight away and then give them a good soaking on 1st September.

And yes Muddywellies feed with half strength liquid tomato food until the leaves die back. As Mr MB says we do our best to repot all our bulbs in pots every year - labour of love or lunacy!

oh yes- oops- i forget bout repot- good to put well rot manure at botom of pot so root hav sumthin to feed on next yeer

Thanks all of you for the advice. Just to make sure I've got it right, I need to;

1. Cut off flowerheads when petals fall off
2. Put those pots in shade, but feed until the leaves die back
3. Allow them to dry off over the summer once leaves have died back
4. Repot in fresh compost in autumn and water from sept/oct onwards

That sounds very manageable and thanks for explaining it all so well!

You've got it Muddywellie