In seed saving, it’s essential to prevent cross-pollination of crops that are not self-pollinating by keeping plants of the same species separated by distance. This keeps seeds collected from open-pollinated varieties true-to-type. Isolating by distance is the most fail-proof way to prevent cross-pollination, but you can get creative when the such isolation distances are not feasible.
Isolation by Containment
When space is limited and isolation by distance is not possible, you can physically isolate plants from each other through the use of isolation tents or blossom bags. Growing insect-pollinated plants inside tents with introduced pollinators prevents cross-pollination. Isolation by containment cannot be used on wind-pollinated crops like corn or beets, as physical barriers can keep insects out, but allows pollen carried by the wind to enter and cross-pollinate these crops.
Isolation Tents and Mosquito Netting
Isolation tents are often used by larger-scale growers. This method can be more challenging for home growers, because generally, pollinators are purchased and introduced inside the cages. Another approach to utilizing isolation tents is known as alternate-day caging. This method involves moving isolation cages between two different varieties in the same species on alternating days to prevent them from cross-pollinating, while still providing them with access to pollinators on the days that they’re not covered. Once fruit is set, you don’t need the plants to have access to pollinators, so you can leave them caged. You don’t need fancy supplies to make an isolation tent; you can make one yourself using mosquito netting and posts (the post help keep the netting off of the plants).
