To save seed there are only three simple processes to know. Once you have an understanding of each of the processes, you can save almost any seed. For specific processing requirements for individual plants refer to an seed saving resource that describes each species in detail.

Dry Seed Processing

Seed is left on the plant to ripen and dry, this is normally well past the usual picking/eating stage. The seeds are harvested, usually by cutting the whole seed pod/flower head or even the whole stalk off of the plant. The seed is then separated from the parent plant; threshing, lightly crushing and hand picking are used depending on the size and type of seed. Fully dry seeds normally separate very easily. The seed is then cleaned from any remaining chaff by sieving, winnowing or using a gold panning action.
Used for; legumes, grains, lettuce, brassicas, onions, beets, carrots, celery etc.

Wet Seed Processing

Involves removing the seed from the overripe fruit, rinsing clean of debris, and then drying. A jar of water can be used to separate seed from debris – seeds usually sink and debris usually floats. Drying the seed quickly and completely after wet processing is very important.
Used for; soft fleshed fruits, melons, peppers, eggplant, tomatillo, pumpkin etc

Fermentation Processing

Similar to wet seed processing, but the seeds and their juices (as in tomato and sometimes melons and cucumbers) are mixed with a little water and allowed to ferment for a few days. The fermentation process breaks down germination inhibitors such as the gel-sack that surrounds tomato seeds. When a layer of mold has formed on top of the water and the seeds sink, the fermentation is complete. Then simply add more water, swish it around, then decant the mold and pulp. This process is repeated several times until all of the pulp, bad seeds (floaters) and mold is removed, then drain the water from the good seeds seeds (sinkers) and set them out on a plate, screen, or paper towel to dry. Once the seeds are thoroughly dry, place them in a moisture-proof container, label and store them for the future.

Used for; tomatoes, cucumbers, pomegranate, some melons and any seeds that have a gel sack surrounding them after washing

Some Examples:

Pea (Pisium sativum)

Easy to save

Family: Fabaceae
Pollination: Self fertile, perfect flowers
Populatuion Size: Minium one, preferably ten or more
Isolation: Easy. Separate varieties by 3-6m, time or physical barrier
Cross pollination: Low risk (within species) by insects
Processing: Dry method
Viability: 3-5 years

Peas are an ideal place to start seed saving as they are truly easy peasy. There are three groups of peas. Smooth-seeded peas
are starchier and hardier than wrinkled-seeded peas; edible-podded peas are more commonly known as sugar peas or mangetouts.GROWING FOR SEED SAVING
It is possible to grow several seed crops in a larger home garden, if possible 3-6m separation should be kept between varieties. Tall varieties of pea need support sometimes as high as 2m. Seeds should preferably be planted direct as they dislike being transplanted and sown at a depth equal to about twice their size. Rouge out any plants that show odd characteristics particularly changes in leaf structure, flower color, pod size or seed character.

Hot tip – Protect seeds and seedlings from birds, slugs, snails and other pests. Young seedlings are irresistible

COLLECTING THE SEEDS
The pods will appear after the flowers open and will develop over a few weeks to eating stage. About three weeks after the eating stage the pods will dry and the peas inside can be rattled (depends on variety). This indicates the seeds are mature and ready to harvest. Pick the pods and then shell out the peas. Dry further by spreading on a tray in an airy location. When dry the peas will split rather than crush and will be impossible to dent when pressed wit your fingernail.STORING SEEDS
The seeds should be sorted and checked before being stored. Select large, well formed peas with no insect damage. If insect damage is present/suspected then freeze the dried pea seed for three days in a domestic freezer. As with most seeds the trick to long storage is cool, dry and dark. Ensure they are properly labelled and drop off at the seed library.

Lettuce (Lactuca sativa)

Easy to save

Family: Asteraceae
Pollination: Self-fertile, perfect flowers
Population Size: Minimum one, preferably four or more
Isolation: Easy. Time, Distance (6m) or physical barrier
Cross pollination: Low risk of cross pollination by insects. Can cross with some other wild species within Latuca genus
Processing: Dry method
Viability: 3-6 years

Most lettuces are annuals and although a cool season crop they can be planted in Nelson throughout the year if care is taken to protect the young seedlings from the elements. In hot, dry Nelson summers lettuces sometimes struggle and prefer to be grown in part shade, keeping the moisture up to them through mulching, watering or high organic matter in the soil. Although most varieties are fairly hardy the red ones seem to do better in frosty locations. Successive sowings will help keep your household in young tender lettuces.

GROWING FOR SEED SAVING
A minimum of ten lettuces should be planted and any that are different or weak can be removed leaving four well spaced, strong plants to save for seed. When stressed lettuces are quick to bolt (go to seed) and care should be taken not to accidentally select for early bolting. As the flower stalk forms the lettuce often turns bitter and is less suitable for eating, in crisphead lettuces the flower stalk sometimes has trouble pushing through the head, a cut in the top of the lettuce can be made to free the flower stalk if required. The stalk can reach 1.5m and should be staked to prevent the plant being blown over and uprooted.

Hot tip – Watch out for rains
when the seeds heads are ripening

Lettuce flowers are made up of lots of florets, which each contain up to 25 seeds. The flowers mature from top to bottom over a few weeks and ripen in the same order. The flowers contain both male and female parts and will readily self pollinate with good seed set. They do however open briefly and cross pollination by insects during this time is possible, although the risk is low. Isolation can be achieved easily by only having one variety flowering at once, a 6m separation from all other lettuces flowering at the same time should provide reasonable isolation. It is also easy to physically isolate lettuce seed flowers by wrapping in horticultural fleece or a fine insect mesh, no insect pollinators are required for good seed set.

COLLECTING SEED
Between two and four weeks after flowering the seed will become ripe and naturally fall from the seed head. One of the main problems with saving lettuce seed is that the seed will easily rot if the seed head gets wet during the ripening process, either protect it from rain or if you are in for damp week the entire plant can be pulled up and hung in a shed to finish ripening. As the seed ripens over a period of a few weeks, you can visit the seed head every other day and shake the loose seed into a clean bucket, or, once the seed is starting to become loose the entire seed head can be cut and left to ripen in the shed for another week or two. Once dry, the seed head can be shaken into a bucket or threshed onto a tarp to remove the seed. In some varieties the seeds may need to be rubbed free.

STORING SEED
The collected seed can then be cleaned by winnowing, sieving, or shaking from one container to another to separate the chaff electrostatically. Cleaning lettuce seed is a dusty process and the dust can irritate the lungs, try not to breathe it. Once clean the seed should be dried thoroughly, labeled and returned to the seed library.