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Friday, November 7, 2014

Saving seeds for beginners

Here is an article I wrote for the GIY magazine 'Grow'.

Saving seeds for beginners
What makes us different to the other apes is our tendency to mess with food. We cook it, ferment it, dry it, grow it and deliberately breed it for certain traits. Our domesticated plants were developed from wild plants, over the last 10,000 years, or so, by farmers and gardeners. None of the early growers had degrees in biotechnology, nor were there any seed companies. Yet, they created all the important crops we use today. They grew, and exchanged their seeds, each farmer developing landraces suited to his or her taste, culture and climate. A huge diversity of types was developed in this way, which gradually spread around the world. We have a vast amount of domesticated varieties, but many are disappearing as ‘BIG-AG’ buys up small seed companies and reduces the number of available varieties. Farmers are encouraged to buy modern hybrid varieties that produce crops conforming to supermarket standards of appearance rather than use traditional ones, from which they can save their own seeds. Legislation in many countries is also making it difficult for farmers to save their own seeds and to sell or exchange them. Most seed packets do not give you much information about the origin of the seeds. They do not even show country of origin. Most seeds are produced in warm dry places like California and Israel, where the predictable weather allows seed to mature without danger of mould. Growing seed form such environments does not prepare them for the Irish climate. By saving you own seeds you can be a part of the evolution of domesticated plants, care-taking rare landraces, and adapting and creating varieties to suit your garden. It is not difficult. Always keep the seeds from the best plants in your garden, and eat the other ones.
One of the first things that early farmers selected for was self-pollinating plants. This is a useful trait when you are trying to domesticate a species as it prevents it crossing back to its wild relatives. Crops such as wheat, peas, common (French) beans and tomatoes are self pollinated. Seeds are produced when ovules in the plants ovaries are fertilised by pollen. When this happens inside a flower and the pollen and ovules come from the same plant it is called self-pollination. These are the easiest plants to start saving seeds from as you don’t have to worry about them crossing with other things.

Some tomatoes, especially the big beef ones and the cherries can cross pollinate. Flowers on these plants have stigmas that protrude out of the flower, but it doesn’t really matter as most of the seeds will be true to type, and if they are not you have the chance of developing your own variety. 

Cross pollination occurs when the pollen from a different plant reaches the ovules. Care must be taken in saving seeds from cross-pollinated plants that pollen you want, is reaching the flowers.

A species is defined as a group of organisms capable of interbreeding and producing fertile offspring.

Plants that are the same species, and have the same Latin Name are able to cross pollinate. For instance cabbage and cauliflower were developed from the same species of wild cabbage, and can therefor cross with each other. So, if you want to save cauliflower seed you don’t want any other cabbage type plants flowering within the distance insects are flying around. The other complication with cross-pollinated plants is that a significant population of plants is needed to prevent inbreeding. For practical purposes 20 plants is usually enough but seed companies would often have a minimum of 200 plants to ensure enough out-crossing. The pollen form wind-pollinated plants, such as beets and maize, travels even further than insect pollinated plants and can cross oceans.
Hybrid seeds are produced by inbreeding lines of vegetables until the genes on both of their sets of chromosomes becomes almost identical. Then, two of these inbred lines is crossed. This produces a population of almost identical plants with one set of chromosomes from each parent. They tend to be more vigorous and and productive than either of the parents but they are an evolutionary dead end as the traits of the succeeding generations of plants is unpredictable as all the genes will be randomly mixed up.
Landraces are farmer varieties that have more variability in them than a commercial variety. They contain more genetic diversity within them than modern varieties. This gives them more ability to adapt to new conditions such as changing climate, diseases and pests.

Saving Tomato Seeds
To save tomato seeds squeeze the seeds of a ripe tomato into a container and leave at room temperature for 3 days until a bit of white mould develops on the surface. Then stir the contents and fill the container up with water. Allow the seeds to settle at the bottom and then pour off the debris. Rinse the seed in a sieve and dry on a windowsill on a plate, (they will stick to paper). Stir as they are drying, to prevent them from sticking together. Remember to label them.

Saving Pea Seeds
to save pea seeds, leave the peas on a few plants to mature. When the lower pods have turned brown, harvest the whole plant and hang it in a dry place. when all the peas are dry you can pod the peas by hand or put them in a container and trample them to extract the seeds.

A variety is a population of plants from within a species that differs from the remainder of the species in certain characteristics.

Drying Seeds
Seeds must be fully dry before they are put in airtight containers and stored. Seeds store best when cool and dry. Seed banks freeze seed for long-term storage and you can too, but be sure it is really dry before you do so. Large seeds take longer to dry than small ones and if you are not sure how dry they are, it is better not to put them in airtight containers.
To test if a pea or bean is ready to store, hit it with a hammer. If it cracks and breaks into small pieces it is ready however if it squashes it is. When dry, cucumber and pumpkin seeds will snap when bent.

Storing seeds
Most seeds will last for a several years in a cool room. Putting them in a fridge in plastic food containers will extend their lives. The table below gives a rough estimate of how long seeds will last. Viability decreases gradually so there is no exact time and it depends on the original quality of the seed and on the storage conditions. Sachets of silica gel will absorb water and if enclosed with your seeds will help to keep them dry.

Germination testing
It is easy to test your seed for viability. Put a few seeds on kitchen paper in a plastic box, or in a small pot of compost. Then put them somewhere warm and see how many come up. Some seeds like it cool like lettuce and spinach, while tomatoes, peppers and other tropical plants like it at least 20C.