Seed saving 101: Isolation distances and planning your garden

My last real post began to explore isolation distances and their role in seed saving. This is a big and complicated topic. I find that sometimes, the best way to grasp an expansive topic is to try to apply it to a more particular situation.

Applying isolation distances to the sub/urban home garden

Let’s start, for simplicity’s sake, with five major summer vegetables you may want to try to save, and we’ll assume you want to try heritage or heirloom varieties:

  1. Beans (‘Kentucky Wonder’ pole bean)
  2. Corn (‘Golden Bantam‘)
  3. Melons (‘Minnesota Midget’ cantaloupe)
  4. Tomatoes (‘Brandywine‘)
  5. Zucchini (‘Black Beauty’ zucchini)

All of these are open-pollinated varieties.

Common name

Scientific name

Variety name

Isolation distance

Population size

Pollinators

Beans Phaseolus vulgaris ‘Kentucky Wonder’ 20’ 10-20 Self
Corn Zea mays ‘Golden Bantam’ 1600’ 200 Wind
Melons, cantaloupe Cucumis melo ‘Minnesota Midget’ 1600’ 10-20 Insects
Tomato Solanum lycopersicum ‘Brandywine’ 40’ 10-20 Self, insects
Zucchini Cucurbita pepo ‘Black Beauty’ 1600’ 10-20 Insects

Table is adapted from A Seed Saving Guide for Gardeners and Farmers by the Organic Seed Alliance, www.seedalliance.org.

The immediate issue visible for most sub/urban home gardeners is that we have nowhere near the space to grow 20 tomato plants and 200 corn plants, so maintaining a population size to ensure good genetic diversity may not be an option. You can still grow enough plants to feed your family, and save your seed and even share it.

Beans:

This, perhaps, is the most reasonable plant of the five for the home gardener to both maintain a population size suitable for maintaining genetic diversity, and also maintain appropriate isolation distances from other bean crops.

Using a square-foot gardening technique, a row of beans 15-20 feet long × 1 foot wide or a double row 10 feet long × 2 feet wide will yield enough to permit attrition due to deer, disease, and occasional errant basketballs, and still have a viable population. And unless you and your neighbor are both trying to grow beans in the only sunny part of land in your neighborhood, which just happens to fall directly on your property line, you’ll probably be able to keep your plants 20’ from another variety of bean plant.

Urban patio gardeners: Beans may be grown in containers, using cage-type trellises to support the vines as they grow. Grow as many plants as your space permits, but do not overcrowd your containers. Plan on one plant per 8″ of container diameter. Spacing from other plants may be more challenging for you. Can you tell what your neighbors are growing?

Seed saving technique:

Enjoy some of your beans, and leave some on the vine until they turn leathery and yellow, tan, or brown in color. Then remove the pods from the vine, and dry them out of direct sunlight for a week. When the beans rattle in the pods, they are ready.

Corn

Corn is tricky. Let’s come back to it in another post.

Melons

Melons likewise are challenging. We’ll address those in a separate post.

Tomatoes

The trouble with tomatoes, from my perspective, is that there are only 200 interesting varieties. How can one possibly pick just one variety to grow in the home garden? I have no discipline: If I have the space to grow 10 to 20 plants such as would be recommended for a good seed-saving population, I will grow 10 to 20 different tomatoes.

Brandywine tomatoes by rsgreen89, via Creative Commons 2.0.

Brandywine tomatoes by rsgreen, via Creative Commons 2.0

It helps that tomatoes are primarily self-pollinating. If it is possible in your garden to grow multiple varieties and observe the 40’ planting distance from other tomato varieties, by all means do so.  But the popularity of home-grown tomatoes means you would do well to pay attention to what your neighbors are growing if your sunniest spot happens to be near your property line.

Acknowledging these challenges for the sub/urban gardener, my best advice from a seed stewardship perspective is to grow as many plants as you can of the variety you love best, say, ‘Brandywine.’ Cluster them together, tend them well, and select appropriately. If you cannot resist growing 15 other varieties, consider growing those well apart from the best-loved variety. Knowing that the other 15 may mix between themselves, if you save seeds from those varieties, keep those seeds for yourself. Keep detailed notes on how those plants behave from year to year, select them as you will for the Brandywines, and if they appear to be quite stable, then you may share them.

And if you live in an apartment and can only grow 1 tomato plant, grow it and enjoy it. If the plant is healthy, save seed from it to use next year. It’s your treasure.

Seed saving technique:

To save tomato seeds, use a wet processing method:

  • Squeeze the pulp and seeds from several saved fruits into a glass jar, and top it off with tap water.
  • Leave it on the kitchen counter for a few days, stirring occasionally. (It will begin to mold, so this may not be the time to have your mother-in-law over for dinner.) The white mold can be stirred back into the mixture with no ill effects.

How to know when they’re finished fermenting? There are several indicators that may be used, but I have had fine luck simply waiting 48 hours. You may want to try the different methods described here and find the method that works best for you.

  • Rinse the seeds several times using a metal mesh strainer. You may need to rub some residue off the seeds if they won’t come clean by a simple rinse. I find the spray attachment that comes on many kitchen faucets works well, as long as the spray doesn’t hit the seeds with full force.
  • Spread the seeds on a cookie sheet and let them dry for a week (it may take up to three weeks for the seeds to fully dry), and store them in a labeled paper envelope placed in a glass jar in the refrigerator.  You may put a packet of silica gel, such as you find tucked into a box of new shoes, in the bottom of the jar to absorb extra moisture, provided the packet is intact and the seeds are well secured in their envelopes.

Zucchini

Good heavens. I can barely keep up with the produce from 1 zucchini plant, let alone the 10 recommended for selection purposes. I should like to see the freezer big enough to hold all the zucchini bread one could make from 20 zucchini plants.zucchini copy

But perhaps your next door neighbor, or one across the street, or both, wants to grow zucchini as well. If you all are concerned about genetic diversity, you can all grow the same variety, splitting the seed packet between you. You might then be able to each select your best plants, save those seeds, and perhaps share a few seeds between each of you to spread the risk.  What are their neighbors growing? If they’re growing a variety of yellow summer squash, you might have an isolation issue. Fortunately, squash are easy to hand-pollinate. You could take this route, and use floating row covers to isolate the plants from the neighbor’s yellow squash.

Urban gardeners: I’m guessing that, due to the plant’s enormous size, heirloom zucchini may not be high on the list of plants to grow on a balcony. If you want fresh zucchini, you may need to go with an F1 variety developed to grow compactly. You can still have grow such plants organically, but heirlooms may simply not be practical for you.

Squash and zucchini are cucurbits, which are notorious cross-pollinators. I’ll get to this in more detail when we explore growing melons.

Seed saving technique:
  • Allow some fruits from the best plants to grow very big and to harden.
  • Harvest them, then allow them to cure at room temperature for four weeks.
  • Remove the seeds, cleaning the pulp from them, and rinse them well.
  • Spread the seeds on a cookie sheet and allow them to dry for several weeks.
  • Store them in a labeled paper envelope in a glass jar in the refrigerator.
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