Question
QUESTION: How long can you keep seeds before their no good? Where do you have to keep them?

ANSWER: Hi Val,
Thanx for your question.  In the wild, the cones of the Sequoia can remain on the tree for 8-12 years or longer.  The seed is shown to remain viable for just as long if not longer.  Some seeds have remained as long as 20 years.  When storing seed, store in a clear jar with a lid and store in a cool, dry, dark place.  I hope this helps.
Tom

---------- FOLLOW-UP ----------

QUESTION: Is it hard o grow a cypress from seed? Also I have some Kudzu seeds, how can I keep this plant under control in a hanging planter?

Answer
Hi Val,
I'm sorry I misunderstood your original question.  For some reason I thought you were asking after sequoia and now I see you were asking after cypress.  What variety of cypress?  If you're talking about bald cypress the seeds require stratification (cold treatment) for 90 days.  Place the seeds in a damp paper towel and seal inside a plastic baggie.  Place in the fridge for 90 days.  After that, plant the seeds 1/4-1/2 inch deep and germination should occur in a few weeks.  I don't know how easy they are to grow as I have never grown them before but most seeds that require stratification will germinate successfully for you if you simply give them the retired wet/cold treatment.

As far as kudzu goes, if you live in the Southern half of the U.S. I believe it would not be prudent to propagate this plant.  In fact, there are restrictions, even prohibitions against propagation in some states.  Contact your local county extension agent for more information.  If you need contact information, I would be glad to provide it to you just give me your general location.  Kudzu has wreaked havoc on the U.S. Southern Pine Forest, choking it out in many areas of the Southeast.  Kudzu has been known to overwinter as far north as Missouri and Kansas.  I hope this helps.
Tom