Purity Technique 1. Select varieties from different families
Select varieties of plants from incompatible families to grow in close proximity to each other to ensure the purity of each variety.
For example, you may grow varieties of Carrot and Spinach within 10cm of each other without risk of cross-pollination.
Purity Technique 2. Select self-pollinating varieties
Select self-pollinating varieties and grow them so that their flowers do not grow within 3 meters of each other to ensure the purity of each variety.
Plants will cross-pollinate within families unless some method of isolation is employed. Some varieties are largely self-pollinating so separating these members by a distance of 3 or more metres is sufficient to prevent cross-pollination.
For example different varieties of pea may be grown if a distance of at least 3 metres is maintaned without risk of cross-pollination.
Purity Technique 3. Use physical barriers
Isolate flowers with bags or cages to ensure the purity of each variety regardless of their proximity to compatible varieties.
Bags are typically employed for plants having large individual flowers and cages used to isolate entire plants. Bags or cages are made of porous material that can breathe but blocks the transfer of pollen. Download the detailed plans and specifications in the PDF document link.
For example different varieties of squash may be isolated from each other by bagging each flower but manual pollination will be required. Typically a small brush is used to tranfer pollen from the male flower to the female flower. Several plants may be caged to isolate them from compatible pollen.
How to save seed
Seed Saving Techniques
Nobody wants seed !
What they want are plants that grow vigourously from their seed (viability) and that produce consistent nutrition, flavours, aromas and/or medicinal characteristics we value and expect (purity).
Below you will find a description of the techniques you will need to ensure that a high percentage of your seed will germinate (are viable) and the plants they produce have the characterisitcs you desire (purity).
Pollinate to transfer pollen from the male flower to the female flower fertilizing it causing it to produce fruit/seed.
Cross-Pollinate to transfer pollen between plants of different characteristics. The offspring of this process will exhibit characteristics predictable by the normal rules of genetics.
Plant Families only members of the same families may cross pollinate.
Oh yes, and step 4, Repeat.
Saving seed is truly as simple as these 4 steps.
The devil is in the details.