The following chart will give you a guideline to saving your seeds. Many factors will affect the viability such as, the seed’s age, humidity, temperature and light.
Also, these numbers are minimum years. If the seeds are kept in optimal conditions you could expect much longer storage times. The germination rates usually starts to decline after that. I will say however, that I’ve germinated tomato seeds 25 years old that were only stored in a closet. I’m not suggesting you will have to same results, but under proper conditions the list below should be more than accurate.

Plant Years of Viability
Artichokes 5
Arugula 3
Asparagus 3
Basil 5
Beans (Bush & Pole) 3
Beets 2
Broccoli 3
Brussels Sprouts 4
Cabbage 4
Carrots 3
Cauliflower 4
Celery & Celeriac 3
Chard 4
Chicory 4
Chives 2
Cilantro 5
Collards 4
Corn 1-2
Cucumber 5
Dill 5
Eggplant 4
Endive 5
Fennel 4
Kale 4
Kohlrabi 5
Leeks 2
Lettuce 3
Marjoram 1
Muskmelon 5
Mustard 3
Okra 2
Onions (green & bulb) 1
Oregano 1
Parsley 2
Parsnip 1
Peas 3
Peppers (hot & sweet) 2
Pumpkins 4
Radishes 4
Rutabaga 5
Sage 2
Salsify 1
Sorghum 4
Soybean 2
Spinach 3
Squash 4
Strawberry 2
Sunflower 5
Tomatillo 3
Tomatoes 5
Turnips 4
Watercress 5
Watermelon 5