There are two categories of plants in terms of seed saving, those with wet seeds and those with dry seeds. When you save wet seeds, you need to wash them to separate them from the surrounding pulp of the fruit. This can be accomplished by putting the pulp in a bowl of water. The seeds will sink while pulp and any dead seeds will rise to the top. The seeds will then need to dry thoroughly before storage. Some wet seeds will also need to be fermented before saving, such as tomato seeds. Fermenting removes substances from the seed that inhibit germination.
Dry seeds are harvested from the plant when their husks or pods have dried. The seeds then have to be separated from the chaff. When the seeds are dry, you can crumble them up and place them in a dish. Swirling the dish will cause the larger pieces of chaff to rise to the top where you can remove them by hand. To separate out the smaller pieces of chaff, you can use screens. One screen will let small pieces of chaff fall through, leaving the seeds behind. The next screen will allow the seeds to fall through, while larger pieces of chaff remain behind.
To separate dry seeds from the chaff using an ancient method called winnowing, you need a breeze or a fan. Put a sheet or bucket on the ground and drop seeds onto it from a height of a few feet. The breeze or fan will blow the chaff away, while the heavier seeds collect below.
There are some tricks and techniques for saving seeds from different plants. In many cases, a plant or two will need to be sacrificed to get the seeds. Vegetables like lettuce, cabbage, and broccoli will need to be allowed to bolt, while for others you will need to allow the fruit to dry or over ripen in order to get the seeds. Account for this when you plan your garden and grow extra plants for the purpose of collecting seeds.
Certain plants will need to be isolated from each other to avoid cross-pollination. This is only important for plants from which you hope to save seeds. For instance, if you have two different varieties of peppers from which you hope to collect seeds, you need to keep them from mixing pollen. These plants can be bagged or surrounded with wind-proof caging. If the plants that are bagged normally require insects to pollinate them, you will have to lift the bag and use a small brush to hand-pollinate the flowers.
To harvest bean seeds, let the pods dry on the vines before you pick them. Shell the beans and let them dry thoroughly before storing. You can harvest most of your beans for eating and leave just a few pods on the vine to dry for seeds.
If you are growing beets and Swiss chard, they will need to be surrounded by wind-proof caging or bagged. They will easily cross-pollinate, even at distances of a mile. Allow your selected beet plants to over-winter. They will flower and produce seeds in the spring. When the seeds are mature and dry on the plants, simply rub them off of the stems. They can be stored as is for up to five years.
To get seeds from broccoli, you need at least ten plants to make sure there is enough of a genetic base. You can harvest the broccoli’s central head to eat and let a secondary shoot on each plant over-winter. Collect seed pods in the spring before they split open naturally. Dry them upside down in paper bags and the seeds will fall from the pods and into the bag.
Cabbage should be isolated from broccoli, collards, cauliflower, kale, and Brussels sprouts. Like broccoli, you need ten plants for a good genetic base. The cabbage plants will need to over-winter, and you will not be able to harvest any for eating from your seed plants. In the spring, collect the pods when they are dry but not yet split.
Carrots can cross-pollinate with Queen Anne’s lace, so they need to be isolated for the purpose of seed collection. Only a small area is needed to let carrots remain in the ground for seeds. Pick the seed umbels when they have dried on the plant. Let them dry, and the umbels will easily crumble away.
To get seeds from cucumbers, let the fruits over ripen on the plant. When fruit is removed from the plant, let it sit for three weeks before removing, cleaning, and drying the seeds for storage.
It is not common practice to collect seeds from garlic for future use. Instead, save a bulb or two and plant the individual cloves to get new plants.
Lettuce produces many flowers throughout its flowering season. Collect dried seed heads from the plants every few days. Hang them upside down in a paper bag or over a tarp. The seeds will fall out as they dry.
Melons are a wet seed plant. Allow melons to be harvested for seeds to ripen on the vines until their skins are very hard. Pick the fruits and let them sit for three weeks. After this time period, you can remove the seeds, clean them and dry them.
When flowers form on the onion plant, you need to let the seeds ripen and dry before picking them. However, you need to watch for this carefully to avoid losing seeds. Harvest them as soon as they are dry. You can only store onion seeds for one or two years before they go bad.
Some varieties of pepper will cross-pollinate, but you can safely grow one sweet pepper and one hot pepper without worrying about separation. To collect seeds, let the fruit mature and fully dry before picking. The seeds can be easily removed from the inside of the fruit at this point.
Allow squash fruits to remain on the vine well past the stage at which they can be eaten. They are ready to be harvested when the skin is hard and leathery. Store the squash for three weeks before opening them for the seeds. Remove the seeds, clean them, and dry them before storing.
Most tomato plants will not cross-pollinate and do not need to be isolated. Pick tomatoes for seeds when they are very ripe and just past the eating stage. Once the seeds are removed, they need to be fermented to remove the germination-inhibiting gel that surrounds each seed. Put the seeds and pulp in a jar and leave it in a warm place. When you see bubbling in the jar for a day or two, remove the seeds and clean the pulp from them. The timing is important. If you allow the seeds to ferment for too long, they will begin to germinate. Watch the jar carefully. The process should take between one and a half and five days.
Original text from http://www.heirloomsolutions.com