Seeds you save from your home production system are accustomed to your climate and growing medium and are adapted to pests in your area. Seeds are generally saved from annual and biennial plants. Perennials are usually propagated through division or cuttings. If two varieties of spinach bloom near each other, the resultant seed is likely to be a cross between the two. Different varieties of peppers should be separated by 500 feet to avoid cross-pollination.
Biennials require more work and commitment.
These plants do not send up seed stalks until the second season. Biennials include beets, Brussels sprouts, cabbage, carrots, cauliflower, celery, onions, parsley, parsnips, rutabaga, salsify, Swiss chard, and turnips. Do not save seed from hybrid varieties if you want plants like the parents. Seeds from hybrid varieties produce a mix of offspring, many of which may have different characteristics than the parent. Unless pollination has been strictly controlled, strange hybrids often result in the next generation.