Friday, November 20, 2015

Successful Seed Saving

Sowing seeds collected from your own food garden can be fun and successful if you stick to a few basic rules. Taking control of the whole cycle from seed to crop and back to seed can be very satisfying. Seed saving allows home gardeners to play a role in preserving valuable heritage varieties and it saves money.



It is thought that mankind began to collect seeds of wild food plants around 11,500 years ago. Initially the purpose was simply to sow these seeds and get a bigger crop than could be collected in the wild.

The next step began, when farmers noticed the difference in quality between seeds collected from just any plant and seeds collected from healthy prosperous plants. Mankind began to selectively collect seed. The resulting plants were better adapted to local climate and soil conditions. Over time these plants became different from the same plants elsewhere in the land. New varieties were born.

Then farmers began to pollinate by hand plants that they thought would be good to combine the characteristics of. This was revolutionary, and led to even more productive, tasty, and nutritious food plant varieties.

Collecting seeds and trying to improve the characteristics of food plants requires a lot of expertise, persistence and patience. This blog post is not about improving the characteristics of food plants. Its aim is to enable you to collect seeds from your food garden each season and grow from them new plants that get a very similar crop the next season.


What you need to know:

Pollination is the process whereby pollen is transferred from the stamen of a flower to the pistil of a flower (see the diagram below). If pollination is successfull one or more seeds may be produced.

Self-pollination is the process whereby pollen is transferred from the stamen of a flower to the pistil of the same or another flower on the same plant.

Hermaphrodite plants have flowers like this

Cross-pollination is the process whereby pollen is transferred from the stamen of a flower of one plant to the pistil of a flower on another plant.

Hermaphrodite plants are plants that have flowers as shown in the diagram above. They have in every flower one of more stamens and a pistil. Around 80% of Earth’s plants are hermaphrodites.

Monoecious plants are plants that have flowers that either have stamens (female flowers) or a have a pistil (male flowers). Some species have male and female flowers on the one plant (for instance pumpkin). Other species have female plants and male plants (for instance Kiwi). This last group is often referred to as being Dioecious.

True-to-seed is the term used for a plant when it is very similar in terms of looks and characteristics  to the parent plant that produced the seed the plant was grown from.

If we want to have a high degree of certainty that the seed we collect from food plants in our garden will produce plants that are true-to-type, we should limit ourselves to collecting seeds from plants that have in each flower both stamens and pistil.  Those plants will almost certainly self-pollinate because there is pollen within millimeters from the pistil in the same flower.

Hybridisation is the process whereby pollen is transferred from one plant to another, and the two plants belong to the same species, but they are not the same variety within the species.

Hybridisation is a natural process that has taken place in nature for as long as there have been flowers. Hybridisation can produce seeds that are not viable.  In other cases plants grown from this seed will be weak.  Sometimes, however, a better-adapted plant is the result and a new variety is born. Hybridisation is the trial and error method that nature uses in the evolution of species.

In the 1950s agricultural scientists developed the methods that allowed mankind to hybridise plants on a commercial scale. That led to the development of many new hybrid plant varieties.

Hybrid plants may produce viable seed, but the next generation grown from that seed will not be just like their hybrid parents. Instead, they will be a completely new combination of the good and bad traits of the plants that were initially crossed to create the hybrid. It is impossible to predict just how the seedling plant will perform or what qualities it will have.


Growing plants from seeds from your own garden will be simple and successful if
  1. Your aim is not to improve plant characteristics, but to produce plants that are true-to-type. 
  2. You only collect seeds of self-pollinating plants 
  3. You don’t collect seeds of hybrid plants 
Following these rules you can collect seeds of peas, beans, tomatoes, capsicums, peppers and lettuce year after year and have a high degree of certainty that you will have very similar plants every year.  There might be no need to ever buy seeds of these plants again.

Did you notice the words high degree of certainty in the previous sentence?  I put them there because I like to make things simple without promising something that can not be delivered.  The truth is that many self-pollinating plants will also develop fruit if cross-pollinated, although the chances of this happening are quite small because because there is pollen within millimetres from the pistil in the same flower.


Let's look at these vegetables individually:

Peas and beans

 Are self-pollinators so there is a high degree of certainty that offspring is true-to-type.
  1. Make sure they are not hybrids. 
  2. Select plants that have grown well and have produced well. 
  3. Once you have picked all the pods you want to eat, and the pods that are going to provide next crop’s seeds are fully formed, keep conditions on the dry side. 
  4. Allow the pods to stay on these bushes until they are completely dried out. 
  5. On a dry day collect these pods. You can at this stage take the peas or beans out of their pods, but you can also leave them in their pods until many months later you are ready to sow your next crop. 
  6. Allow to completely dry for a few days in a well-ventilated dry out-of-the-sun spot.
  7. Put them in a paper bag or glass jar and document variety and date of harvest.
  8. Store in a dark, dry, well-ventilated spot with even temperatures.
  9. These seeds do not need any further treatment before being sown. 
An over-ripe pea pod that I will allow to dry completely on the bush
Capsicums and peppers

Are self-pollinators so there is a high degree of certainty that offspring is true-to-type.
  1. Make sure they are not hybrids. 
  2. Select plants that have grown well and have produced well. 
  3. Allow some fruits to stay on the plants until they become fully ripe and start to wrinkle. 
  4. Now take the seeds out of these fruits and allow them to completely dry in a moderately warm well-ventilated out-of-the-sun spot. 
  5. Allow to completely dry for a few days in a well-ventilated dry out-of-the-sun spot.
  6. Put them in a paper bag or glass jar and document variety and date of harvest.
  7. Store in a dark, dry, well-ventilated spot with even temperatures.
  8. These seeds do not need any further treatment before being sown. 
Tomatoes

Are self-pollinators so there is a high degree of certainty that offspring is true-to-type.
  1. Make sure they are not hybrids. 
  2. Select plants that have grown well and have produced well. 
  3. Allow some fruits to ripen fully 
  4. Now squeeze the seeds out of these fruits onto some kitchen paper towel and allow them to completely dry in a moderately warm well-ventilated out-of-the-sun spot. 
  5. Allow to completely dry for a few days in a well-ventilated dry out-of-the-sun spot.
  6. Put them in a paper bag or glass jar and document variety and date of harvest. 
  7. Store in a dark, dry, well-ventilated spot with even temperatures. 
  8. These seeds do not need any further treatment before being sown. 
When you are ready to sow your tomato seeds the following season, just cut out individual seeds and plant them.  There is no need to remove the bit of kitchen towel that may be attached to the seed.

If you want to keep tomato seeds longer than one year, Point 4 needs to be:
  • Put seeds and gel in a glass jar with some water. 
  • Store in a warm place. 
  • Stir or swirl the mixture twice a day. 
  • The mixture will ferment and the seeds should sink to the bottom within five days. 
  • Pour off the liquid and rinse the seeds 
  • Spread them out to dry on paper kitchen towel. 
Fermentation removes germination inhibitors and the gelatinous sheath from seeds. Fermented tomato seeds that are stored properly may remain viable for six years.

My 'Truss' tomato seeds spread out over a piece of kitchen towel
Lettuce

Are self-pollinators so there is a high degree of certainty that offspring is true-to-type.
  1. Make sure the variety is not a hybrid 
  2. Select a plant or plants that have grown well and look healthy. 
  3. Lettuces flower continuously over a long period.  A flowering lettuce will almost always have flowers and seeds in all stages of maturity. 
  4. Rub dry mature seed heads between thumb and forefinger above a plate to release seeds. 
  5. Allow to completely dry for a few days in a well-ventilated dry out-of-the-sun spot.
  6. Put them in a paper bag or glass jar and document variety and date of harvest. 
  7. Store in a dark, dry, well-ventilated spot with even temperatures. 
  8. These seeds do not need any further treatment before being sown. 
lettuce seed

How about other plants in my food garden?
If they are non-hybrid self-pollinators not mentioned above, then you will be able to easily produce the next true-to-type crop from their seeds.

If they are cross-pollinators, things are a bit more complicated and your next crop may be less predictable.

Take pumpkins for example: they are monoecious.  Some flowers on a pumpkin plant will be male, some will be female. Plants will therefore simply not self-pollinate. Pistils will accept pollen from any compatible other flower including plants of a different variety and therefore offspring may not be true-to-type.  I remember one year growing pumpkins from seed collected by a friend the previous season and ending up with oddly-shaped not very nice tasting produce.  Quite disappointing.

Parsley seeds maturing on the bush

 If you want the next generation of cross-pollinating plants to be true-to-type
  1. Make sure the variety you want to take seed from is not hybrid 
  2. Grow only one variety of this vegetable in your garden
  3. Make sure that your neighbours over the fence do not grow a different variety of the same vegetable that flowers at the same time as your plants.  The term separation distance is used. It is the distance needed between different varieties of the same species to ensure that cross-pollination with another variety does not occur. That distance is different for each species.
  4. If you really want to grow more than one variety at the same time, choose varieties that do not flower at the same time, or study seed saving further before proceeding (see suggested reading at the end of this blog post).

Brassicas, Corn, Cucumbers, Parsley, Pumpkin and Silverbeet are all monoecious and can cross with other varieties. Separation distance between varieties are often officially more than a kilometre.

If it would be your aim to harvest seeds of these cross-pollinating vegetables every year for quite a few years into the future, you also need to consider the minimum number of plants that should be grown to preserve inherent genetic diversity, and this takes us into territory that is very interesting, but well beyond the scope of this blog post.


This blog post was just an introduction to the subject of seed saving.  Saving seed can be fun and rewarding.  For some people it becomes a wonderful hobby or even profession.


For further information go here:


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