Howdy Comet, I regularly make nettle feed for all my veg and plants.
first, to answer your question, of course you can make nettle tea from nettle tea bag material,
but it is going to be far less effective, and really its not the way to go.
its true the fresh stuff does stink, but its doesn't stink until you disturb it,
and curiously when it is diluted it has an almost medicinal smell, unlike comfrey tea which stinks all the way.
bite the bullet and make some fresh stuff;
cram a bucket full of freshly pulled nettles (wear gloves) put an old plate or plastic lid on which is slightly smaller than the bucket opening,
and then weigh it down with a rock or a brick; fill with water and leave in a warm place....OUTSIDE! for about 10 days.
best thing to do then is strain off the concentrate carefully by using the weighing down plate to keep the icky mess in the bucket.
strain the drained off concentrate a second time using some net curtain material, so as to prevent your watering can rose from clogging up;
if you are using a sprayer, best strain again with a really fine filter, such as a synthetic tea bag (the silk type)
you can top up the bucket a second time and get a second run which will be weaker but still worth using.
dilute 10-20:1 water: nettle tea (20:1 for spraying).
give it a try.
