In cleaning up for the new year I have found in used seeds some have a plant date and others don’t. Can these seeds be used?
The viability of seeds will be determined by their storage method. Even if the “best before” date has not been reached, there can still be a possibility that they will not grow.
If there are expiration dates on your packages, they should be stamped with a wording like “Packed for 2017”. Seeds that are only a year or so old and whose packets are still unopened generally germinate very well.
If they are older than 5 years and the packs were opened or the seeds were stored where the temperature and the humidity add up to more than 100 when combined it is usually a no-grow.
If your seeds were stored in a garage or basement they will have a better chance of being viable, because those environments are typically dark, cool and dry. The temperature remains pretty constant. Most seeds stay viable longer if stored at a constant temperature of 5 degrees or lower.
There is a 10-day germination test you can do to see if they have any growing power whatsoever.
Place some sample seeds inside moist paper towels and slide the towels into a plastic bag. Mark the type of seeds on the front, but don’t seal the bag. Let them sit in the warmest room of your house and re-moisten daily if necessary. Viable seeds should sprout by Day 10, or by the germination date period stated on the seed packet. If they don’t, or if a very small percentage sprout, get fresh seed. If you decide to use your seeds, it might be a good idea to sow them a little thicker than you usually would in order to make up for seeds that won’t germinate. The following article is a good article outlining this method:
Best of luck with your spring planting!