I have read on this blog a number of times that one should buy garden seeds, however my question is:- HOW LONG CAN YOUR HEIRLOOM GARDEN SEEDS KEEP IN YOUR FREEZER AND STILL ENABLE YOU TO HAVE AT LEAST A 90% GERMINATION WHEN YOU DECIDE TO USE THEM?We know that Brassica such as Cabbage, Cauliflower, Broccoli, and other vegetables like lettuce, carrot do not carry seeds therefore one would prefer to s