Pollination Guide
Crops can either be self pollinated or pollinated by insects or wind. Plants that are self pollinated are called selfers. Those that are insect or wind pollinated are called crossers.
In order to maintain genetic purity of a particular variety, plants must be isolated from other plants of a similar species. This is especially important for crops that are insect and wind pollinated. For instance if you are growing two kinds of cucumber, say Marketmore and Lemon, and a bee collects pollen on one and visits the flowers on the second variety, the seed on the second variety are potentially fertilized. When harvested the cucumbers look the way one would expect. The Market more is long and green and the Lemon is round and yellow. The consequence of the two varieties crossing shows up the next year when the seeds are planted when the resulting fruit shows a combination of the two types.
The recommended isolation distances will be difficult for the home gardener to achieve. Varieties can still be kept pure by staggering the planting times of similar varieties and by using screened cages to keep pollinators at bay.
The following chart provides information on how a plant is pollinated, how much isolation distance is needed to keep the variety pure and how many plants should be grown to preserve the broadest possible genetic base within the variety. Maintaining genetic diversity within a variety is critical to the variety's ability to continue evolving and adapting to environmental conditions.
An annual variety completes its life cycle and seed production in one season. A biennial produces leaves in the first year and fruit and seed in the second year of growth.
Seeds from plants marked with an asterisk require either fermentation or over ripening.
| Annual Crops | Pollinator Type |
Isolation Distance | Min # plants needed |
| Bean, bush | self | 20 ft. | 25-50 |
| Bean, pole | self | 1/2 mile | 25 |
| Bean, fava | self | 1 mile | 25 |
| Bean, runner | self | 1/2 mile | 25 |
| Corn | wind | 2 miles | 200 |
| Cucumber* | insect | 1/2 mile | 10 |
| Eggplant | self | 50 ft. | 10 |
| Lettuce | self | 25 ft. | 10 |
| Melon* | insect | 1/2 mile | 10 |
| Mustard | insect | 1/2 mile | 50 |
| Okra | self, insect | 1 mile | 10-15 |
| Pea | self | 50 ft. | 25-50 |
| Pepper | self | 500 ft. | 5-10 |
| Pumpkin* | insect | 1/2 mile | 10 |
| Radish | insect | 1/2 mile | 50 |
| Spinach | wind | 2-5 miles | 10-20 |
| Squash* | insect | 1/2 mile | 10 |
| Sunflower | insect | 1/2 mile | 10 |
| Tomato* | self | 10 ft. | 5-10 |
| Watermelon* | insect | 1/2 mile | 10 |
| Biennial Crops | Pollinator Type |
Isolation Distance | Min # plants needed |
| Beet | wind | 2-5 miles | 10 |
| Broccoli | insect | 1/2 mile | 50 |
| Brussel sprout | insect | 1/2 mile | 50 |
| Cabbage | insect | 1/2 mile | 50 |
| Carrot | insect | 1-3 miles | 30 |
| Cauliflower | insect | 1/2 mile | 50 |
| Celery | insect | 1/2 mile | 10 |
| Chin. cabbage | insect | 1/2 mile | 50 |
| Collard | insect | 1/2 mile | 50 |
| Endive | insect | 1/2 mile | 10 |
| Kale | insect | 1/2 mile | 50 |
| Kohlrabi | insect | 1/2 mile | 50 |
| Leek | insect | 1-2 miles | 10-20 |
| Onion | insect | 1-2 miles | 10-20 |
| Parsley | insect | 1 mile | 10 |
| Parsnip | insect | 1 mile | 10-20 |
| Rutabaga | insect | 1/2 mile | 50 |
| Swiss chard | wind | 2-5 miles | 10 |
| Turnip | insect | 1/2 mile | 50 |
Source for information in table: Abundant Life Seed Catalog