Seed saving 101: Cucurbits

To continue with the seed-saving series, let’s focus on cucurbits (melons, squash, cucumbers). As with corn, the seed-saving challenge for the home sub/urban gardener will be to maintain a population size that will permit seasonal attrition and genetic diversity.

Common name

Scientific name

Variety name

Isolation distance

Population size

Pollinators

Melons, cantaloupe Cucumis melo ‘Minnesota Midget’ 1600’ 10-20 Insects

Know what you grow.

When it comes to cucurbits, the gardener must know the scientific names of the crops she wants to grow. Cucurbits will cross-pollinate within their species (Cucumis melo with other Cucumis melo) but not inter-species, i.e., within the genus. So you can grow ‘Minnesota Midget’ cantaloupe next to your zucchini (Cucurbita pepo), and they’ll be fine. But you cannot grow cantaloupes, honeydew melons, and crenshaws together (all Cucumis melo) without expecting cross-pollination.

Common names in this family can be misleading. Armenian cucumbers, for example, are Cucumis melo, but regular salad-type cucumbers are Cucumis sativus. Summer squash, another cucurbit, is Cucurbita pepo, as are pumpkins, but winter squash may be Cucurbita pepo (acorn, crookneck, scallop-type, and spaghetti squash; zucchini; and pumpkins) Cucurbita maxima (hubbard and turban squash, buttercup squash, and some pumpkins), Cucurbita moschata (butternut squash), or Cucurbita argyrosperma.

In short, if the Latin name is the same, you can’t grow them together without cross-pollination. If the first half of the name is the same but the second half isn’t (Cucurbita pepo and Cucurbita moschata), you’ll be fine.

Getting them growing

First, keep cantaloupes and other muskmelons 1600 feet away from other muskmelons (what’s your neighbor growing over his fence?).

Cucurbits are insect-pollinated, and given the distressing decline in native pollinator populations, it’s not fair to assume you’ll have a healthy supply of wild pollinators nearby. Without an abundance of natural pollinators, you may have to resort to hand-pollination to get any fruit set. Fortunately, hand-pollinating is quite simple.

Cucurbits produce male and female flowers on the same plant. Fruit will form from the female flowers if they are pollinated. Female flowers can be distinguished from male flowers by the fruit (the bulbous part, or ovary) at the base of the flower. Male flowers do not have an ovary.

To hand-pollinate your plant, pick a male flower from the plant and peel back its petals, exposing the pollen on the anthers. Find a female flower, and gently open its petals if necessary.  Rub the pollen on the stigma, and let the petals fall back to their original position. One male flower can pollinate multiple female flowers.

Male acorn squash flower (Cucurbita pepo) by Forest and Kim Starr [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons

Female acorn squash flower (Cucurbita pepo) showing large, dark-yellow stigma. By Forest and Kim Starr [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

Female acorn squash flower (Cucurbita pepo) showing large, dark-yellow stigma. By Forest and Kim Starr [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons

Pollinating the female stigma with the male anther. Photo by Jay at Scientific Gardener under Creative Commons 3.0.

Pollinating the female stigma with the male anther. Photo by Jay at Scientific Gardener under Creative Commons 3.0.

The flowers tend to open early in the morning, and close as the heat of the day increases, so plan your pollination activity accordingly. A peculiar habit of cucurbits is that the female flowers often develop later in the season than the male flowers. Day length, light intensity, and temperature all influence the ratio of male to female flowers produced. Long, hot days yield more male flowers; cooler temperatures and shorter days yield more female flowers.

Saving the seed:

Muskmelons are easy. When the melon is ready to eat, the seed is ripe. Separate the seeds from the flesh, rinse them clean, and allow them to dry on a screen away from heat and direct light. Store in a clean glass jar or paper envelope in a cool, dry place.

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Seed saving 101: Understanding isolation distances for corn

Continuing the erratically-scheduled Seed saving 101 series…

Saving Sweet Corn

Who doesn’t love corn? But when each plant yields only 2 ears or so, it can be hard for the average home gardener to maintain a reasonable population size to permit good genetic diversity and account for seasonal attrition.

Ohio corn field By Graylight (Flickr) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons

Corn is wind-pollinated, and to prevent cross-pollination for seed-saving purposes you must maintain more than 1/3 mile (some sources say more than ½ mile) between your corn and anyone else’s.  If you live in a typical American suburban cul-de-sac development, avoiding contamination might be impossible if anyone else on your block grows corn. If you don’t have 200 plants, you might be able to use row covers to shelter your corn from other varieties. Frames can be made out of flexible PVC piping that are both inexpensive and can support row covers, but this might be more work than you want to do.

A short word about GMOs: In 2010, 86% of the corn planted commercially in the US contained some modified genetics.[1] Genetically modified corn seed, such as Monsanto’s Roundup-Ready seed, is not sold to the home gardening market. However, a 2004 pilot study by the Union of Concerned Scientists found that modified genes had found their way into 50% of the non-GMO corn seed they tested. Their test seeds had been purchased from the same retailers that sell to US farmers. The UCS data suggest a 1% contamination rate in the seeds of traditional varieties, which equates to 6250 tons of transgenically-derived seeds planted in fields of traditional crops.[2]   In 2004, approximately 81 million acres of corn were planted in the US, and 45% of all corn planted were biotech varieties.[3] In 2013, that amount had grown to 97.4 million acres, of which 90% were biotech varieties.[4] Such statistics suggest that in the past ten years since the UCS pilot study, accidental contamination of non-GMO seed stocks may have also increased, and may have found its way to a corn seed packet near you. And if you live within approximately 1/3 to ½ mile of a farm where corn is grown commercially (particularly for commodity corn, used in the production of ethanol or for livestock feed), the potential for direct GMO cross-pollination with your home-grown crop exists.

Truckload of corn

Truckload of corn, Wikipedia photo released to public domain.

Hybrids are not the same as genetically modified organisms, but seed saved from hybrid corn will not come true. Open-pollinated corn may cross with nearby hybrid varieties by wind pollination, which may result in unfavorable traits in your second-generation corn seed.  Sweet corn will also cross-pollinate with field corn and ornamental corn, resulting in less-sweet sweet corn.

How to grow and save the seed:

Plant your corn in blocks, not rows, to ensure the heavy pollen fully fertilizes all the seeds and the ears fully develop. Hand pollination is simple and is a good way to control the fertilization (and prevent cross-fertilization) of your corn:

  1. Place bags around the ears of corn before the silks emerge, securing the bags tightly.
  2. Separately bag the tassel, which contains the pollen.
  3. Shake the pollen from the tassel and allow it to collect in the bag.
  4. Then de-bag the ears, shake the pollen onto the silks, and re-bag the ears to prevent cross-pollination.

To harvest seed:

Allow the ears to dry on the plant. For sweet corn, harvest when a fingernail pressed into a kernel releases a milky fluid.[5] Peel back the browned husks and allow the seeds to dry on the cob in a well-ventilated space.  Twisting the dried ears will encourage the kernels to fall off the cobs, and you may also rub the kernels off by hand.[6] Store in a glass jar in a refrigerator or other cool, dark place.

Further tips on saving corn seed may be found at the Seedsavers.org blog, http://blog.seedsavers.org/preventing-gmo-contamination-in-your-open-pollinated-corn/.


[1] Acreage, Released June 30, 2010, by the National Agricultural Statistics Service (NASS), Agricultural Statistics Board, U.S. Department of Agriculture. Pp. 24, 32. http://usda.mannlib.cornell.edu/usda/nass/Acre/2010s/2010/Acre-06-30-2010.pdf

[2] Gone to Seed: Transgenic Contaminants in the Traditional Seed Supply. (pp. 1-2). Union of Concerned Scientists, Cambridge, MA: 2004. http://www.ucsusa.org/assets/documents/food_and_agriculture/seedreport_fullreport.pdf

[3] Acreage, 2004. National Agricultural Statistics Service (NASS), Agricultural Statistics Board, US Department of Agriculture,  p. 24. http://usda01.library.cornell.edu/usda/nass/Acre//2000s/2004/Acre-06-30-2004.pdf,

[4] Acreage, 2013. National Agricultural Statistics Service (NASS), Agricultural Statistics Board, US Department of Agriculture,  p. 25.  http://usda01.library.cornell.edu/usda/current/Acre/Acre-06-28-2013.pdf

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.

Seed saving 101: Understanding isolation distances

In order to save seed and, more to the point, be a good steward of the health and success of open-pollinated varieties, it’s important to take a few precautions.

Perhaps the most challenging one, particularly for (sub)urban gardeners, is that of observing some isolation distances. Isolating plants is a way of preventing the pollen of two closely related varieties from mixing, thus ensuring a relatively stable and pure strain of seed.

A pure strain of seed? Didn’t we want genetic diversity? Well, yes, but not too much. There is a balance to be struck: We want enough diversity to maintain a healthy and well adapted variety, but not so much that the heirloom cabbage you love doesn’t resemble that same cabbage anymore. Seed saving and seed stewardship are a blend of art and science, but don’t be terrified or put off by that. You alone will not irrevocably destroy your favorite variety of cabbage.

Of course, if your whole ambition is to produce a totally different variety by throwing everything into the pot and seeing what comes out, plant with abandon, but please don’t share your resulting seed and promise it’s going to be the original. And be considerate of your neighbors, and any plans they may have for their own gardens.

First steps in planning your summer gardening and seed-saving activities:

  1. Assess your site. Understand the space you have available to grow your crops and the light the site receives.
  2. Identify the crops you want to grow.
  3. Learn your plants’ scientific names, and which other plants share that scientific name. That means both parts of the name: the genus and the species (not the part in single quotation marks). It’s especially important if you wish to grow cucurbits (squash, cucumbers, melons, pumpkins) or brassicas (broccoli, cauliflower, cabbage, collards, kale, to name a few).
  4. Depending on the size of your property and your proximity to your neighbors (especially critical if you grow in a community garden), learn:
    1. What your neighbors’ plans are for their summer gardens, if any.
    2. Whether anyone in your vicinity is a beekeeper.

The topic is a big one to grasp (bigger than I realized when I set out to research the issue), so I’ll break down an example in my next post.

Seed saving 101: The lowdown on hybrids

(Part 3 in a series in honor of the Durham County Seed Library)

Yesterday, we looked at the differences between open-pollinated plants and heirloom varieties. Today, we’ll explore the basics of their agricultural counterparts, the hybrid varieties.

What is a hybrid?

Hybrids are created when individuals of two different genera, species, or varieties mate. Hybrids occur in nature: Leyland cypress (Cupressus × leylandii), peppermint (Mentha × piperita), and wheat are well known naturally occurring hybrids.  Next time you shop for plants at the garden center or nursery, if you see a multiplication sign (×) in the plant’s name, you’ll know the plant is a hybrid.

In agriculture, hybrids are often created by controlled pollination, a process in which the pollen of one parent is applied to the stigma of the other parent, and the flowers of the “mother” plant (the pollen recipient) are isolated (for example, securely enclosed in paper or fabric) to prevent further pollination.

F1 hybrids

F1 usually refers to the first generation produced from a specific cross of two distinct, uniform varieties (two “pure lines”). If seeds are saved from the fruits of these F1 hybrid plants, they will not be “true to type;” that is, they won’t reliably resemble the parent plant.  To get a similar plant to the one that produced those fruits, a gardener would have to cross the original parents again. When it comes to vegetables and flowers, F1 hybrids are typically vigorous plants and good producers, but new seeds must be purchased year after year.

What would happen if I planted those seeds from the F1 fruit?

Unless the hybrid is sterile, plants will grow from those seeds from F1 fruits. These F2 plants (second generation) won’t look like their parent, though, and they may not look much like each other. But if you have an appetite for a long-term project (say, close to a decade), you might be able to select for good traits, save those seeds and grow out successive generations, and over time bring that variety to stability. Then you’ll have created your own open-pollinated variety, and you can name it whatever you like.

There’s so much talk about growing open-pollinated plants. Are hybrids bad?

No, hybrids aren’t bad. They fulfill an important role in agriculture, whether it’s for the backyard gardener or the large-scale industrial farmer.

Truckload of corn

Truckload of corn, Wikipedia photo released to public domain.

The problem in modern agriculture, for which hybrids receive the lion’s share of the blame, is the widespread loss of genetic diversity. We all remember from biology class that variety in a species’ gene pool enhances that population’s ability to adapt to changing conditions and survive over the long term. When farmers plant F1s heavily or exclusively, their fields are filled with identical genetic copies of one another. There is no evolution; favorable traits are not selected and propagated. And when an open-pollinated variety is not planted, it does not have the opportunity to grow and adapt to changing conditions, and over time the variety deteriorates.

Meanwhile, insects and diseases are evolving, changing, and adapting. Restricting genetic diversity in the plants we grow means that over time we’re effectively building better bugs and blights.

The long-term prospects of planting monocultures of F1 varieties include massive crop failures and famines, and/or the heavy use of pesticides and herbicides and whatever residual impacts on human health those products may have.

So hybrids themselves aren’t bad. Exclusive planting of hybrids, however, is very short-sighted.

Now I feel guilty for liking my ‘Silver Queen’ corn, ‘Packman’ broccoli, and ‘Big Beef’ tomatoes. Will I be a bad citizen if I grow them this year?

No, but try growing some open-pollinated varieties as well. You’ll need to maintain isolation distances for some crops, but that’s a matter I’ll write about later this week.

Seed saving 101: What’s the difference between open-pollinated and heirloom?

Continuing with the homage to Durham County’s new seed library, let’s examine the difference between open-pollinated seeds and heirloom seeds.

What’s the difference between an open-pollinated seed and an heirloom seed?

Heirlooms are seeds of plants that have been tended, selected, shared, and handed down for generations within a particular location or community. Some seed companies categorize heirlooms by the age of the variety (e.g., if seeds of a particular plant have been recorded as being handed down for 100 years or more). Seed Savers Exchange classifies heirlooms by tracing a plant’s documented history of preservation, emphasizing the plant’s ties to a particular group of people.

Grandpa Ott's morning glory

Grandpa Ott’s morning glory. Photo by Seed Savers Exchange. http://www.seedsavers.org/onlinestore/Flower-Seeds/Flower-Grandpa-Otts.html

For example, Seed Savers Exchange founder Diane Ott Whealey’s great-grandparents brought some morning glory seeds from Bavaria to Iowa in the 1800s. Upon her grandfather’s death, Diane Ott Whealey founded the Seed Savers Exchange to continue this hand-me-down tradition of conservation, and Grandpa Ott’s morning glories are found in gardens across the country, including mine.

Seed Savers Exchange further differentiates between heirlooms and “heritage” varieties, which are “old-timey” plants that may have no particular connection to a particular people.  And there are “modern heirlooms,” or modern open-pollinated varieties in various stages of emerging tradition, being bred and selected by a handful of seed companies who care deeply about plant genetic diversity and stewardship.

radishesSo to summarize:

  • Open-pollinated seeds, as we learned yesterday, are pollinated by insects, birds, wind, or other means, whose offspring closely resemble their parents from generation to generation. OPs may be of any age or tradition.
  • Heritage varieties are old, traditional open-pollinated plants, that may or may not be connected to a group of people. Heritage varieties are open-pollinated, but not all OPs are heritage varieties.
  • Heirloom varieties are old, traditional open-pollinated plants that are variously defined as being handed down by generations in a particular location or context, and/or which may be greater than 100 years old. Heirlooms are open-pollinated, but not all OPs are heirlooms. Heirlooms are heritage varieties.
  • “Modern heirlooms” is another name for open-pollinated plants bred more recently (say, post-advent of commercial agriculture, up until today), whose tradition among groups of people or locations is emerging. They’re neither heirlooms in the traditional sense, nor are they heritage varieties, but they are being bred in the same tradition and may become heirlooms or heritage varieties in years to come.

Study hard. The exam will be tomorrow.