Do seed packages with dates on them, do they expire?

State and federal seed laws require seed companies print dates on the seed packages. Each state has different requirement, ranging from 9 to 18 month. West coast states usually have longer dates than eastern states, probably having to do with when the laws were set, western states were still the "frontier" states so they were allowing the seeds to be sold in a longer time period. Seeds don't "expire" Per Se after the 9-18 month after the printed dates. Vitality is used to measures how viable seeds are, the longer the time has passed, the poorer the vitality of the seeds. Different seeds maintain their vitality different. Beans, cucumbers and peas will last 5-6 years, while onions, lettuce and carrots probably only 1-2 years, that is from when the seeds were harvested, not what's printed on the seed package. Commercial seed sellers can sell their seeds as long as the germination meets the state requirement. Vitality is not a required element. So to answer your question, you can use past date seeds, just be aware that some may not come up fast. And avoid using old onion/leak seeds, because they have the least storage life.

Good luck and happy gardening!

Yeah, sort of. It really depends on what seeds you are talking about. Some lose viability with simple exposure to normal air temperature and moisture. Some are not so sensitive to heat and moisture. And some actually do better is first exposed to moisture or heat. Some will not even germinate unless exposed to heat. The seeds of the matillija poppy require that you build a small fire above the planted seeds in order for them to germinate. Some seed packages I purchase fresh every year have too because older seed do not germinate. Some seed that are over five years old have germinated well for me (cockscomb if one).

The date on the packages is the year they were packaged. Seeds can keep for long periods of time depending on the seed and how they are stored. Some like cool and dry, some like to be frozen, just have to look up each seed type and check them individually.

The expiration date is less important than how the seeds are treated after they are purchased. Exposure to heat, light and high humidity can destroy seeds quickly, a cool, dry, dark area is best for storage and the retention of their optimum germination.

They do not really expire but as the package gets older the number of seeds which will successfully germinate will decrease.