Seed saving is an important part of any organic garden for a number of reasons and is sometimes known as permaculture. The main reason to preserve your seed is to protect the heirloom varieties of plants that maintain bio-diversity in our ecosystem. These food stocks may not always be available from your local seed packet company as they are considered unpopular or unprofitable. Remember too that by saving our seed we become more self-sufficient, we save money, and we avoid genetic engineering of our food.
There are a few principles that we must understand before we can go on. Save only open pollinated seed. This seed is not modified in any way and will breed true to the parent. Hybrid plants are usually sterile or may revert to a plant similar to one of it's grandparents. We don't need this. After all these plants were bred out to remove some of their less desirable traits or to encourage a trait that we may not find desirable. Hybrid plants are also patented and it is therefore not legal to replicate them by seed, cutting, or other method. If a plant seed packet contains either F1 or F2 in brackets after the plant name it is most certainly a hybrid and not suitable to our purposes. The same goes for cv. This means cultivated variety and thus is also unsuitable for our purposes. On the other hand if the name on the packet is Latin with a common name afterwards then we are all set. These seeds are usually not manipulated by the hand of man.
At first try to stick to annual. These produce seed every year. Biennials produce seed every two years and that becomes something of a hassle in climates where there is a limited growing season. Perennials are just plain easier to propagate via cutting or division.
Do not keep seed from insect or disease ridden plants. Inferior plants make inferior seed.
At first stick to self pollinating plants such as bean, pea, lettuce, and tomato. You will have better success and avoid the dreaded cross-pollination. Other ways to ensure that your seed is true is to grow only a single type of any given plant. If you grow purple beans and green beans chances are that you will end up with seed that produces only green beans. This problem can be avoided by using row covers, plastic tenting, or cheesecloth to cover your plants. The added bonus to this is that it will help repel insects, though if you need the insects to pollinate the plants then this may not seem like such a bonus. When the flowers are ready for pollination then you must then remove the covering and grab your trusty cotton swab and play bee to your waiting plants. This can be a lot of work and generated a lot of questions from my neighbors last year who wondered what I was hiding when all I was doing was keeping watch over my black zebra heirloom tomatoes.
Sources for public domain, non-hybrid, organically grown, and open pollinated heritage seed for Canada, the U.S. and the U.K. are linked at the bottom of the page.
Here are some general how tos on seed saving.
Legumes are by far the easiest. Things like beans or peas simply need be left on the vine till seasons end and the seed removed from the pods and allowed to air dry.
Solanaceaes such as tomatoes and peppers need a bit more work. Cut the fruit in half and squeeze the insides into a dish of warm, not hot; water. Leave this for a couple of days till mold grows on the top of the mixture. Drain off the scum that forms and the seed that has sunk to the bottom of the container is your viable seed. Dry these seeds out on a plastic or china plate for a week or so and you are all set for the spring. The nasty mold serves a purpose. It breaks down the gelatinous coating on the seed and produces anti-biotics that keep the seed free from disease.
Cucurbits such as cucumber or squash must be left on the vine for as long as possible. Eggplants too. These plants do not produce mature seed in a ripe fruit. Only an over ripe one. When cleaning up the vines at the end of the year it is not unusual to find an old yellow ugly cuke still hiding under the brown leaves. This is the perfect plant to collect your seed from. These seeds simply need to be washed off and dried out for a week or so.
Always dry seed on a plastic, glass, or china plate. Paper towel or newspaper is a mistake many people make. The seed sticks to it in drying and never comes off.
After you have dried out your seed take each type and place it in a dark contained. Label each container as all seed seems to look the same come spring. Place these in a cold dark place to store till spring. The freezer works well but be sure to place the seed packets in a glass container. Plastic passes moisture after a time. The extra bonus to this storage method is that seed that needs stratification (a time spent below freezing to start germination ) will be ready for planting right away.
Instructions for saving seed from specific plants listed alphabetically can be found here.
Seed Sources: For Canada Seeds of Diversity's on-line Heritage Plants Database
For the U.S Seed Savers Exchange
For the U.K. Henry Doubleday Research Association