Plant Isolation Distances Table

Please note, these distances have been formulated for rural environments – no one has data applicable to urban growing, but the suspicion, and the experience of most SLOLA members, indicate that the distances will vary from these, and sometimes by quite a bit. In the final analysis, one needs to learn one's own growing situation and note air flow and insect activity. These charts also do not account for 'organic' methods which almost invariably means more insects interacting with the plants and create further variances from the figures below.

Plant	Isolation Distance (Ashworth)*	Isolation Distance (USDA)	Pollinator
Amaranth	¼ to 2 miles 1	—	wind, insects
Arugula	½ mile (2640')	660 feet 7	insects
Basil	150 feet	—	insects
Bean, Common	0 to 1 mile 4	0 5, 4	self 2
Bean, Fava	0 to 1 mile 4	0 5, 4	self 2
Bean, Lima	0 to 1 mile 4	0 5, 7, 4	self 2
Bean, Tepary	0 to 1 mile 4	0 5, 7, 4	self 2
Beet	5 miles	—	wind
Broccoli	1 mile	660 feet 7	insects
Broomcorn	—	660 feet 7	self 2
Brussels Sprouts	1 mile	660 feet 7	insects
Cabbage	1 mile	660 feet 7	insects
Cantaloupe	½ mile	¼ mile 7	insects
Carrot	½ mile	—	insects
Cauliflower	1 mile	660 feet 7	insects
Celery	1 mile	—	insects
Chinese Cabbage	1 mile	660 feet 7	insects
Chinese Mustard	1 mile	660 feet 7	insects
Chives	1 mile	¼ mile 7	insects
Collards	1 mile	660 feet 7	insects
Cilantro	½ mile	—	insects
Corn	2 miles	660 feet	wind
Cotton	—	¼ mile 6	self, insects
Cowpea	0 to 1 mile 2	0	self 2
Cucumber	½ mile	¼ mile 7	insects
Dill	1 mile	—	insects
Eggplant	50 feet	—	self 2
Fennel	½ mile	—	insects
Garlic	1 mile	¼ mile 7	insects
Garlic Chives	1 mile	¼ mile 7	insects
Gourds	½ mile	¼ mile 7	insects
Kale	½ mile	660 feet 7	insects
Lamb's Quarters	5 miles	—	wind
Lettuce	25 feet	—	self 2
Melon, Honeydew	½ mile	¼ mile 7	insects
Melon, Musk	½ mile	¼ mile 7	insects
Mustard	½ mile	660 feet	insects
Okra	1 mile	825 feet	self, insects
Onion	1 mile	¼ mile	insects
Parsley	1 mile	—	insects
Pea	50 feet	0 2	self 2
Pepper	500 feet	30 feet	self, insects
Potato	30 feet 3	30 feet 3	self, insects 3
Pumpkin	½ mile	¼ mile 7	insects
Radish	½ mile	660 feet 7	insects
Sorghum	—	660 feet	self 2
Spinach	5 miles	—	wind
Squash	½ mile	¼ mile 7	insects
Sunflower	½ to 3 miles	½ mile	insects
Swiss Chard	5 miles	—	wind
Tomatillo	0 4	30 feet 7	self 2
Tomato	0 4	30 feet	self 2
Turnip	1 mile	660 feet 7	insects
Watermelon	½ mile	¼ mile	insect

Footnotes:

1. Green amaranths may need only ¼ mile, grain amaranths up to 2 miles.
2. See paragraph on Self Pollination in Distance Isolation in the article on Saving Seeds True-to-Type.
3. Potatoes are not commonly reproduced from seed.
4. See note on tomatoes and beans in the article on Saving Seeds True-to-Type.
5. "Distance adequate to prevent mechanical mixture is necessary".
6. Isolation distances for cotton vary from 100' between similar varieties, to ¼ mile between 'upland' and 'Egyptian' types ('foundation' or 'preservation' grade).
7. Extrapolated from similar species.

* Seed To Seed, Ashworth, Suzanne © 2002, Seed Savers Exchange

Some Tips and Helpful Considerations in Seed Saving

In addition to saving seeds for your own use, for useful seed saving it was better to choose one or two crops that you would focus on entirely for seed saving and swapping. Doing this allows you to develop a seed over time that suits a particular soil and climate, and, accurately observe its characteristics and needs. For that seed or those seeds, keep detailed accounts of as much information about everything observed or known about them. :

• color
• odor
• size
• soil
• water
• sun
• cultivation and harvesting time
• variations in the seed
• where you planted it
• scientific name (as the colloquial name of it may vary)
• popular names
• uses
• origin (where it came from)
• date of seed preparation, etc.

As you prepare the seed for saving, you would then make detailed notes about these seeds.

Seeds without accurate information become nearly useless

Receiving seeds without knowing anything about them other than their variety renders the seed almost useless for planting. Although it may be fun, in terms of productivity it is akin to starting from zero.

Tips for saving seeds

• Select and keep the best plant for collecting seeds, don´t eat it.
• Clean the seed as dirt will encourage bacteria or fungus to grow and this will rot the seed.
• Keep them clean and dry.
• Paper bags are better than plastic bags.
• Put the paper bags then in clean, dry jars with lids.
• Maintain in a cool and dark place, if you can.
• Create a place for saving and organizing your seeds.

It is better to have a small quantity of seeds to save and exchange for which you have an abundance of information than to take on too much to manage information.  

Seed Saving Basics

Tools

The most important tools in your kit are

awareness – if you are planting a variety to save, you will plant that variety in a way to ensure success of growing it and harvesting seed from it.

patience – because saving seeds takes time and really, if you're a gardener, you are already patient.

observation – look for differences and similarities – choose earlier, or later plants, or the ones with white flowers and not red, or the seeds that have a different look.

Useful tools for seed saving (you would be surprised how many of these you can do without)

First you probably really would like to have...

2 buckets or totes – collecting into and for winnowing.

Jars or small plastic tubs/yogurt containers – for fermenting and wet processing seed.

Plate or baking sheet or window screen - for seed drying.

Air tight containers and/or envelopes - for storing seeds. Keep them cool, dry, and rodent proof. Masking (or other writable) Tape - for labeling things.

Pruners - important for clipping, picking, cutting and harvesting stuff.

Sieve or fine mesh strainer - to drain water from wet seeds.

Hardware cloth screen - for screening seeds from debris

Bonus points if you have or can borrow...

Tarps - drying seed heads, catching seed or winnowing onto.

Sturdy storage container - protection from mice.

Box fan - for when there is no consistent wind for winnowing.

Food Dehydrator - for drying seeds to ideal (low) moisture content for storage. Must set thermostat lower than 95 degrees.

If you find seed saving to fit your lifestyle and tastes, there are other seed savers all around you! You can come to the Seed Library of Los Angles (www.slola.org) meetings on the third Saturday of each month (except December) at The Learning Garden, located on the campus of Venice High School. We talk about seed saving, plant breeding, saving varieties and finding new and very tasty varieties of vegetables. Perhaps one day we will get to California Native plants, medicinal plants and ornamental plants. (We already have sweet peas and calendulas. It's just a matter of time and interest.) Our web presence is getting better; we have an active Facebook Page and Instagram.

A Seed Saving Glossary

This is not a comprehensive glossary, but should define most terms you will find in seed saving literature.
alternate-day caging - A technique that allows two different flowering varieties to be pollinated by insects without being cross-pollinated. Cages constructed of wood, wire, or plastic frames are covered with fine screen. One variety is covered with cages one day, allowing the other to be visited and pollinated by insects; the cages are switched each day to allow insect access to the previously caged variety.
anther - Organ where pollen is produced.
chaff - Broken pieces of dried seed capsules, stems, leaves and other debris mixed in with seeds.
characteristics - General features caused by unidentified complexes of genes including but not limited to freeze tolerance, cold tolerance, regional adaptability, winter hardiness, early maturation, and flavor.
cleaning screen - Screens with different-sized openings are used to separate seeds from chaff. The screen number denotes the number of openings that will cover a one inch line. A screen is selected with openings just large enough to let seeds drop through without the chaff or as in the case of larger seeds, a screen selected to allow the chaff to drop through without the seeds. (See page 36.)
cross-pollination - When pollen is exchanged between different flowers from the same or different plants.
dehiscent - A seed capsule opened to discharge seeds is dehiscent. Seeds must be harvested before this process takes place and the seeds are lost. In some varieties, the seed capsules literally explode.
dioecious - A species with male flowers and female flowers on separate plants as opposed to monoecious.
dominant trait - The variation of a specific, identifiable gene that results in obserable traits. For example, tall is a dominant trait in pea plant growth. Crosses with bush varieties will usually result in tall varieties. See "trait."
F1 hybrid - The "F" in F1 hybrid stands for filial or offspring. F1 means the first generation offspring after cross-pollination. The majority of F1 hybrids are sterile or produce offspring unlike themselves. See "hybrid."
F2 hybrid – The second generation offspring and so on.
filament - Tube that supports the anther where pollen is produced.
flail - The process of fracturing or crushing seedpods in order to free the seeds. This can take the form of everything from simply rubbing broccoli pods between your hands to driving over bean vines with a car or bribing high school students to jump up and down on seeds.
flower - The part of a plant where reproduction takes place and seeds are produced.
hybrid - Varieties resulting from natural or artificial pollination between genetically distinct parents. Commercially, the parents used to produce hybrids are usually inbred for specific characteristics.
inbred – reproduction of plants using parents that are significantly similar over time. In some plants this is not a problem (tomatoes and lettuce, for example) as they have flowers with both male and female and are typically fertilized within the flower before it even opens (see 'selfing'); other plants, needing a wide variety of genetic information to remain healthy cannot last long with such a limited gene pool.
inbreeding depression - A loss of vigor because of inbreeding. Inbreeding is the result of self-pollination or pollination between two close relatives.
insect pollination - Pollen is carried from one flower to another by insects.
monoecious - A species is monoecious if it produces single plants with separate male flowers and female flowers on the same plant.
open-pollinated - Open-pollinated varieties are stable varieties resulting from the pollination between the same or genetically similar parents. Not hybrid.
ovary - The female part of a flower that contains the ovules. Fertilized ovules develop into mature seeds.
perfect flowers - Individual flowers that contain both stamens and pistils, that is to say, both male and female parts.
pistil - The female reproductive organ in a flower made up of the stigma, style, and ovary.
pollen - Equivalent of sperm in plants. Pollen grain fertilizes plant ovules.
pollination - The process of sexual fertilization in plants. The male chromosomes contained in pollen are combined with the female chromosomes contained in the ovules; pollination can be done by insects, wind, water, birds or bats. In most vegetable crops pollination is carried out by wind or insects.
recessive trait - The variation of a specific, identifiable gene that results in observable traits only if the dominant trait is not present. For example, wrinkled pea seeds result only in varieties where the dominant smooth-seed trait is missing.
rogue - The process of removing or destroying plants with unwanted characteristics or traits.
selection - The process of saving the seeds from plants that exhibit desirable characteristics and traits. To identify desirable characteristics, plant the same variety in different environmental conditions, or plant different varieties in the same environ mental conditions.
self-pollination (selfing) - When pollination takes place within a single flower, usually before it opens. Other flowers or plants are not needed. Self-pollinating flowers are called "perfect flowers" because they contain the stamens that produce pollen and the pistil that receives the pollen. Isolation distance to prevent cross-pollination is not necessary unless insects are known to invade the flowers before pollination is complete.
silique - Long, tube-like seedpod that splits in half.
stamen - A flower's male reproductive organ consisting of the filament, anther, and pollen.
stigma - The opening in the pistil through which the pollen passes to the ovary.
style - Contains the pollen tube between the stigma and the ovary through which the pollen is carried.
thresh - A term used by growers and seed savers to describe the process of separating seeds from chaff; they can be separating for grain to eat or for seeds to save, the term is ubiquitous.
trait - A specific feature traced to an identifiable gene or group of genes. Pea traits traceable to single genes include vine growth (bush or tall), seed texture (smooth or wrinkled) and disease resistance (fusarium, enation mosaic, and powdery mildew).
viable - A viable seed is one that will germinate and produce a vigorous plant. Seeds must not be harvested before they have matured enough to be viable. There is wide variation in the point of maturity at which a seed can be harvested and the time passing when the seed will still be viable. Seeds have been known to remain viable for hundreds of years, but in practice, many seeds are no longer viable even after five years.
vigor - Strong, vibrant germination and growth. A desirable characteristic.
wind pollination - When pollen is carried from one flower to another by the wind.

winnow – A seed cleaning technique still used from ancient times to clean seeds by moving air from a fan or breeze to separate heavier seeds from lighter chaff. 

A Seed Savers Bibliography

The New Seed Starter's Handbook, Bubel, Nancy © 1988, Rodale Books, Once you have saved 'em, you gotta grow 'em. I had always started my own seeds, but when this book was really 'new,' I learned a lot more about growing plants from seed. This is still the classic, go-to book on the subject. The authority still.

Enduring Seeds: Native American Agriculture and Wild Plant Conservation, Nabhan, Gary Paul ©2002, University of Arizona Press Not a seed saving book per se, but a valuable background investigation to the seeds of Native American agricultural.

Where Our Food Comes From: Retracing Nikolay Vavilov's Quest to End Famine, Nabhan, Gary Paul © 2008 Shearwater Again, not a seed saving book, but Nikolay Vavilov's research into the seeds of our foods is fascinating reading and helps ground a reader in the history of seed collecting and the reasons why we want to save seeds from the wilds.

Breed Your Own Vegetable Varieties: The Gardener's & Farmer's Guide to Plant Breeding & Seed Saving , Deppe, Carol © 2000 Chelsea Green This is the most exhaustive and thorough book on the process of seed saving. Written with loving appreciation of seeds like no other book I've ever read, Carol Deppe is at once an authority on seeds and plant breeding and a knowledgeable gardener whose books I snatch up and devour as fast as possible. If you have interest in this field, buy this book now.

The Garden of Invention: Luther Burbank and the Business of Breeding Plants, Smith Jane S. © 2009, Penguin Press HC Like most folks interested in new plant varieties and the process by which we get new plants, I have a reverence for Luther Burbank, one of America's premier plant breeders. Burbank brought us the Burbank potato, Santa Rosa plums, Shasta Daisies and hundreds of other plants. His work in plant breeding places him with Henry Ford and Thomas Edison in Americans who brought innovation to the world. His story makes for some wonderful reading, Jane Smith has done a good job.

Heriloom Vegetable Gardening – A Master Gardener's Guide to Planting, Seed Saving and Cultural History, Weaver, William Woys, © 1997 Henry Holt & Co You can still get this on CD from Mother Earth News, but why the publisher has let this book go out of print is an absolute mystery to me. There is no other book that gives the history to so many seeds so thoroughly. Another work of love, Weaver's book has no peer from the past or present; nothing comes anywhere near to it and it should be republished without hesitation.

Some Lovely Seed Saving Resources

Agricultural Resources Service Germplasm Resource Information Network ARS-GRINThis is a government depository of seeds – mostly commercial crops and mostly grain crops. However, if you have a project and you need some 'germplasm' (AKA seeds), a simple email request and they will send you a packetful – my wheat seed (Federation 41) was an accession from California, grown prior to 1942.

Association Kokopelli  Very much like the Seed Savers' Exchange in America, Association Kokopelli, a non-profit organization in France, was set up in 1999 to take up the torch of Terre de Semences, which was forced to close down by a ministerial decree (Ministry of Agriculture) with draconian conditions for the legal registration of ancient vegetable v arieties in "A List for Amateur Varieties." Association Kokopelli since 1999, has blossomed all over Europe presenting an imposing collection of ancient vegetable varieties. Many members of the Association are very deeply involved in the protection of alimentary biodiversity and the safeguarding of traditional varieties.

***Organic Seed Alliance  One of the premier sources for information and assistance – these are the folks that put out the seed saving manual I use in my classes. They have a lot of good solid information that we all want to use. Blog posts are terrific!!***

SeedAmbassadors Project  From Oregon, this is a comprehensive seed site with seeds sorted into the Easy and Hard to save categories. They offer workshops and tours of their 'Open Oak Farm' near Eugene. 

Seed Library of Los Angeles, SLOLA  Some very good information on seed saving and definitely oriented to our climate and our urban ecology.

Seed Savers Exchange  This is out Granddaddy of seed saving outfits in the United States. Membership is currently $50 (I've been a member since it was $25/year). They have an amazing amount of diversity in their catalog, but the true strength of SSE is the members that offer seed in their annual Seed Savers Exchange Yearbook. It is a gold mine that is very beneficial. They have also started carrying a selection of seed saving items (like those shown in the workshop).

SlowFood USA  It is hoped we can align our efforts with Slow Food USA to gain a greater audience and get our message out loud and clear.

Southern Exposure Seed Exchange  I like the fact that they carry seed saving supplies. I got my corn shoot and silk bags from these folks. And they do have some very different varieties – this is where I originally found the lettuce: Drunken Woman Frizzy Head! Also carries supplies for seed saving. An excellent resource.  

Pollinating Mechanisms & Systems in Common Vegetable Crops

Crop Common Name	Crop Species	Primary Pollinating Mechanism(s)	Pollinating system	Wild Crossable Species in US
Onion	Allium cepa	insects	cross	N
Garlic	Allium sativum	insects	most are sterile	N
Garden Chives	Allium schoenoprasum	insects	cross	N
Garlic Chives	Allium tuberosum	insects	cross	N
Dill	Anethum graveolens	insects	cross	N
Celery	Apium graveolens	insects	cross	Y
Beet	Beta vulgaris	wind	cross	Y
Swiss Chard	Beta vulgaris	wind	cross	Y
Mustard	Brassica juncea	insects	cross	Y
Kale	Brassica napus	insects	cross	Y
Broccoli	Brassica oleracea	insects	cross	N
Brussels Sprouts	Brassica oleracea	insects	cross	N
Cabbage	Brassica oleracea	insects	cross	N
Cauliflower	Brassica oleracea	insects	cross	N
Collards	Brassica oleracea	insects	cross	N
Kale	Brassica oleracea	insects	cross	N
Chinese Cabbage	Brassica rapa	insects	cross	N
Mustard, Chinese	Brassica rapa	insects	cross	Y
Turnip	Brassica rapa	insects	cross	Y
Pepper	Capsicum annuum	self	self #3	N
Lambsquarters	Chenopodium album	wind	cross	Y
Escarole/ Endive	Cichorium endivia	self	self #2	N
Radicchio/ Belgian Endive	Cichorium intybus	insects	cross	Y
Watermelon	Citrullus lanatus	insects	cross	N
Cilantro	Coriandrum sativum	insects	cross	N
Crop Common Name	Crop Species	Primary Pollinating Mechanism(s)	Pollinating system	Wild Crossable Species in US
Armenian Cucumber	Cucumis melo	insects	cross	N
Cantaloupe Melon	Cucumis melo	insects	cross	N
Honeydew Melon	Cucumis melo	insects	cross	N
Musk Melon	Cucumis melo	insects	cross	N
Cucumber	Cucumis sativus	insects	cross	N
Pumpkin	Cucurbita pepo	insects	cross	Y
Winter Squash and Show Pumpkins	Cucurbita maxima	insects	cross	Y
Winter Squash	Cucurbita moshata	insects	cross	Y
Summer Squash and Fall Squash	Cucurbita pepo	insects	cross	Y
Carrot	Daucus carota	insects	cross	Y
Arugula	Eruca sativa	insects	cross	N
Fennel	Foeniculum vulgare	insects	cross	N
Lettuce	Lactuca sativa	self	self #1	Y
Gourds	Lagenaria siceraria	insects	cross	N
Tomato	Lycopersicon lycopersicum	self	self #1/#2	N
Basil	Ocimum basilicum	insects	cross	N
Parsley	Petroselinium crispum	insects	cross	N
Lima Bean	Phaseolus lanatus	self	self #2	N
Common Bean	Phaseolus vulgaris	self	self #1	N
Pea	Pisum sativum	self	self #1	N
Radish	Raphanus sativus	insects	cross	Y
Turkish Eggplant	Solanum gilo	self	self #2	N
Eggplant	Solanum melongena	self	self #2	N
Spinach	Spinacea oleracea	wind	cross	N
Fava Bean	Vicia faba	self	self #2	N
Cowpea	Vigna unguiculata	self	self #2	N
Corn	Zea mays	wind	cross	N
Self #1: self pollinating species, outcrossing is usually < 1%
Self #2: self-pollinating species that often outcross between 2-5%
Self #3: self-pollinating species that may cross at rates > 5%