Controlling Cross-Pollination: How to Keep Seed Lines Pure in Your Garden

Saving seeds? Cross-pollination between varieties muddies traits. Control is possible — but requires strategy based on how your plants pollinate.

Self-Pollinating Crops (Easier to Isolate)

Beans, peas, lettuce, peppers, tomatoes, eggplant. Flowers pollinate themselves. Crosses rare but possible.

Isolation: Plant different varieties 10+ feet apart. Better: stagger planting times.

Insect/Wind-Pollinated Crops (Harder)

Onions, cucumbers, corn, squash, pumpkins, broccoli, beets, carrots, cabbage, cauliflower, melons, radishes, spinach, turnips. Need pollen from other plants.

Isolation: 100+ yards — impossible in most gardens.

Hand-Pollination Technique (The Practical Solution)

1. Identify a flower to save seed from.
2. Collect pollen from same variety (small brush).
3. Transfer to target flower.
4. Isolate the flower: Large → tie shut with string. Small → cover with paper bag (not plastic — traps heat). Secure.
5. Tag the fruit/seedpod.

Alternative: Grow One Variety Per Species

Simplest for home gardeners. No isolation needed if no other varieties nearby.

Pure seed = predictable plants. Worth the extra step.