No harm in sowing to find out.

Only way to know is to try them! The garage is likely to be a bad place to store seeds--too hot and humid in the summer--but many seeds are surprisingly durable.

Give it a try. Perhaps your seeds are as tough as the ones I will mention to you now..... When I was in Uzbeckistan ( couldn't go there now without loosing my head I suppose) I purchased at an outdoor market a carved snuff box made out of a gourd which I still keep as a souvenir. Inside the gourd I could hear its seeds rattling around inside when I shook it. Twenty years later I shook five seeds out of it and planted them.....every one of the seeds germinated!

There it goes again! The above answer about the gourd seed was posted by me...Loosestrife..I don't know why I have been occasionally cursed with the avatar of Iciar. Hmmmm ..The Curse Of The Avatar Of Iciar"...sounds like the title of a mystery novel:)

Seeds will remain viable for at least 2 years. From that point, viability rate declines according to species. Onions, leeks, alliums are usually dead after 1 year. I agree with above, try sowing them and see what happens. They will require a lot of nurturing, however, before you realize what you have. You may also discover why you tucked them away in the garage and forgot about them.

Loosestrife, lots of us (me included) have been Iciar at one time or another -mystery and remedy so far unsolved...

Nellie, if you can still read the instructions just follow them - some will be best sown direct into the ground, others would be better started off in seed trays. If you get a pointed stick and push it through the packet you can stick it in the compost to remind you which is which.

many seeds remain viable for several years. if they are foil packed then they will probably be fine. excess temperature and high humidity tend to be their down fall.

I did a stint at the millennium seed bank back in 2000 and seed is stored at 5% humidity and 5 degrees Celsius.

nothing to lose in trying is there? I regularly give old seed a chance

The only old seed I would automatically discard is parsnip seed. I was told many years ago that I would get poor results from previous years seeds. As they take a while to grow and need to be cared for I opted for new seed. I have grown good crops of garden peas from seed more than 10 years old. They were stored in a tin in a cool shed. I always use left over seeds. There are usually far more seeds than one needs in a packet. You can always compost any seedlings which are not up to scratch.