But first, here are the seeds that aren’t worth saving except under very specific circumstances:  

• Don’t save squash family unless you are isolated and are growing only one kind of winter squash. They cross-pollinate easily and the resulting seeds can produce some very awful tasting and sometimes semi-poisonous offspring. That said, if there is only one cucumber (or squash) within bee flight distance, your odds of getting good quality seed is decent.

• Onion seeds are very short-lived. One year is about it. Many onion varieties are hybrids so won’t produce “true” seeds anyway. Stick with buying them each year.