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The selection of seeds can seem like an overwhelming task, especially if you are looking at a half dozen seed catalogs on a cold winter's day in January. When I look at seed catalogs, my eyes get bigger than my belly, and my mouth starts watering at each description of a different variety of each plant. Pretty soon, I have checked off enough different kinds of seeds that if I were to actually grow all of them, I would need a 600-acre farm and an impressive staff of workers.
Seeds are a very compact form of material wealth. A single packet of 30 tomato seeds that costs $2 can easily produce bushels and bushels of tomatoes--enough to make salsa and spaghetti sauce for the family for a year with leftovers to sell or give away. In addition, seeds, when properly selected and saved, are an insurance policy against hard times.
Anyone with limited space should be picky about seed selections in terms of climate preferences, productivity per unit area, disease resistance, and taste preferences. And if you save seed from plants grown the prior year , you will dramatically reduce the need to purchase seed.
Also, raised-bed practices don't sow seeds in a row too closely together and then go back and thin out half the plants-thus wasting the seeds-as the directions on the seed packet instruct. In intensive agriculture, each seed is planted individually at the optimal spacing the first time around-so not a single seed is wasted.
Thus, the seed orders placed by a mini-farmer after the second year of farming will likely be a small number of hybrid vegetables selected for a particular reason, a few plants for which saving seed was either too difficult or unsuccessful, and a handful of new crop varieties that the farmer wants to try out. The full order for a mini farm that will feed a family of three plus generate optional replacement income will probably amount to only $100 worth of seeds plus shipping after the second year if the farmer saves seeds from annual vegetables.
Explanation of Plant Varieties
There are two terms that will be used interchangeably in the remainder of this section and are used periodically throughout this guide that need to be understood: variety and cultivar. In the sense in which I use the terms, they have the same meaning, but to explain what I mean, I have to get into a bit of biology.
Living things are categorized by biologists according to broad categories first and then into ever-finer categories. The broadest categories would be, for example, "plants" and "animals. " The order of classification by plant scientists is kingdom, division, class, order, family, tribe, genus, and species. A variety is a subset of a species, and a cultivar is a cultivated variety.
The actual meaning of the word species is disputed even among scientists, but the generally accepted definition is that a species is made up of a population capable of interbreeding. Typically, two plants are considered to be members of the same species if they can interbreed and produce seeds that will grow plants that will also produce seeds. Thus cabbage, cauliflower , and broccoli are all members of the same species because they can interbreed with each other . However , there are certainly significant differences between these plants! The fact that two plants are members of the same species doesn't make them identical.
If you look through a seed catalog under "broccoli, " you will find anywhere from 3 to 20 different types of broccoli. The sixth edition of the Garden Seed Inventory lists 32 different open-pollinated types of broccoli. These various types of broccoli have differences in taste, color , disease resistance, vitamin content, how long they take to produce a broccoli stalk, and a host of other important characteristics. Each of the different types of broccoli is its own variety. Some food crops, like broccoli, have a very small number of varieties in existence, but others, like tomato, have over a thousand different varieties.
You might select a particular variety of a given crop for any number of reasons-taste, pest resistance, short season, and so on.
This is what I am referring to when I talk about a plant variety. In open-pollinated varieties, the traits that distinguish one variety from another are reliably inherited from one generation to the next.
Existing plant varieties are the culmination of untold thousands of years of careful selection for various traits; new varieties are created in the same fashion all the time. Since plant characteristics are heritable, as a mini-farmer , you will have the ability to select the best-growing plants of a given variety as parents for new seeds, and over time you can end up creating your own specifically adapted plant varieties.
Selecting Plant Varieties
A mini-farmer needs four types of information to select plant varieties: local climate, available varieties, personal tastes, and plant spacing/ yields. To this basic information you will eventually add your own experiences.
Local climate information can be found from the local agricultural extension service or from the Web site of the National Climatic Weather Center . The Web site Weather.com also has a section specifically for gardens. The idea is to find out the length of the local growing season, so that plant varieties can be selected that have enough time to fully mature. A farmer in Virginia will have a much wider selection of appropriate corn and watermelon to choose from than a farmer in Vermont.
Because open-pollinated varieties of crops produce seeds that can be used to grow the same crop again the next year , they are a much better choice for mini-farmers. Seed can be saved from the most productive or hardy plants so that, over time, the open-pollinated variety that the farmer started with has been specifically adapted to that farm's climate and growing conditions. None of this is possible with interbred hybrids, which don't produce reusable seed, making open-pollinated seeds the better default choice of the farmer.
The matter of hybrids has been oversimplified a bit. Given a few years of careful selection and adequate space, it is possible with many (though not all) hybrids to convert them into a new true-to type open-pollinated variety that preserves the desired traits of the hybrid but allows for saving seeds. For details on how to do this, see Carol Deppe's excellent book How to Breed Your Own Vegetable Varieties.
There are also some cases in which hybrids provide a significant advantage over otherwise equivalent open-pollinated varieties; corn is probably the best example. The difference in productivity between hybrid and open-pollinated corn can be huge, with the hybrid producing considerably more, and when a farmer is raising food in a very small area, differences in productivity make a difference.
There are also instances in which hybrid plants incorporate traits such as disease resistance, and using a hybrid variety can save the farmer from needing to use fungicides on the crops. Outside of such cases, the overwhelming preponderance of a farmer's crops should be open-pollinated.
The good news about open-pollinated seeds is that they have become increasingly popular and are available from a number of companies at good prices. The Seed Saver's Exchange publishes a book called Garden Seed Inventory that describes and lists all of the open-pollinated varieties available for every garden plant along with commercial sources for every plant listed. The Seed Saver's Exchange is also a membership organization ($35/year) in which members make thousands of varieties of homegrown seeds available to each other at modest cost via two annually published compendiums provided to members.
A list of seed companies with whom I have had good experiences is provided at the end of this guide, but use it as a starting place rather than a limitation. The open-pollinated seed business is very competitive, and excellent service is the rule rather than the exception. Most seed companies provide free written catalogs and Web sites containing a wealth of valuable information.
An important aspect of selecting seeds is the need for experimentation. There are hundreds of varieties of peas, beans, carrots, and other crops available, and each variety will perform differently because of climatic and soil differences as well as genetic variations that affect flavor . It is good to set aside a small area just for experimenting with new crop varieties and keep careful notes of the results.
Since many important characteristics of a plant variety are hereditary, it makes sense to save seeds from plants that do best in your own environment and to avoid saving seeds from plants that do poorly. This is most reliable when dealing with self-pollinating, plants, as both the mother and the father of the seed are known.
For insect- or wind-pollinated plants, though, only the mother is known. Even so, it is better to know that at least one of the parent plants was superior.
The problem of unknown parentage can be dealt with by culling inferior-performing plants before they are mature enough to pollinate or by using hand pollination to ensure that both parents are known. Either way, by selecting parentage, the farmer constantly increases the seed pool in quality and productivity.
As previously noted, one of the advantages of open-pollinated seeds is that they can be saved so that the need to purchase seeds each year is reduced. Like anything else, there are costs and benefits that the farmer has to consider , and in all likelihood you will end up saving seeds from some crops but not others. A mini-farm exists as a way to produce food rather than an exercise in seed saving. Some seeds, like tomato and pepper , can be saved with minimal effort or inconvenience while others such as cauliflower will require significant efforts and land.
If the production and sale of seeds is something you are interested in, then extraordinary efforts to save seed are worthwhile.
Outside of that, if buying a packet of seed for $1.50 saves hours of effort and tying up land that would otherwise be productive, it makes sense to buy the seeds. You will need to make that determination on the basis of your own circumstances and interests.
Saving seeds is a broad enough topic that entire books have been written on this subject alone. The gist, though, is straightforward:
Nature mandates that plants reproduce themselves, and plants procreate by producing seeds. If these seeds are saved and replanted, they will re-create the original plant.
There are three major sets of plant attributes that affect seed saving. The first is whether the plant is annual, biennial, or perennial. Annual plants produce seed every year and are planted newly each year . Biennial plants require two years in the ground to produce seed. Perennial plants will continue to grow from year to year but often produce seed annually. Second is whether the plant is predominantly self-pollinating or predominantly cross-pollinating.
Cross-pollinators require pollen from another plant to make seed, while strongly self-pollinating plants may fertilize their own flowers before the flowers even open! This attribute exists on a continuum with beans, for example, being almost exclusively self-pollinated and corn being exclusively cross-pollinated. Finally, the actual seeds will require either dry processing or wet processing, depending on the nature of the fruit. Spinach seeds are dry like grains and will be processed differently from tomato seeds immersed in fluid.
These attributes ultimately determine how much effort and land the farmer has to invest to produce seed. Biennials require overwintering and, especially north of Maryland, special attention so that they live through the winter. Plants that are predominantly cross-pollinating require a fairly large population, sometimes as many as 400 plants, to avoid a phenomenon known as "inbreeding depression" in which seed produced from an insufficient quantity of parent plants exhibits progressively decreased vigor and productivity. Seed processing generally, whether wet or dry, can require a fair amount of time. Table 16 lists the seed-saving characteristics of a number of common crops.
Saving seed from biennial plants presents difficulties for the mini farmer whose every square foot of garden bed is important, and also because plants that are wintered-over in the garden complicate crop rotation schedules and the use of cover crops. Luckily, most biennial plants flower and set seed early in spring so they are out of the way in time for summer planting.
A good compromise for farmers who wish to raise their own biennial seeds is to set aside one or two beds for the specific purpose of producing seed. Such beds can be protected over the winter with a hoop tunnel such as the one described in section 13.
Inbreeding Depression and Genetic Diversity
In Table 16 is a column labeled "Min #. " This signifies, for outbreeding/crossing plants, the minimum number of plants of that variety that must be grown together to avoid inbreeding depression.
For those plants that are self-pollinating, the number in that column (followed by an asterisk) represents the minimum number of plants from which seed should be saved to preserve a good cross-section of the gene pool for that particular variety. These numbers represent the plant populations used in commercial seed production. If the seed is being produced for home use, there is generally little harm in reducing the population by 25% or even 50%.
For seed production, it is important to observe the minimum isolation distances given in Table 16 . These distances are for producing seed for home use. For commercial distribution, the distances would be greater in many cases. These isolation distances specify the minimum distance that a plant has to be from another plant of the same species but a different variety to keep the two from interbreeding and producing seeds that won't duplicate either plant. At first glance, this looks easier than it actually is for the following reason.
On a farm that occupies less than a quarter acre, all of the plants are within 100 feet of each other , meaning that for purposes of seed saving, there won't be enough isolation distance available to grow more than one variety of a given species without using isolation cages or other special seed-saving techniques to prevent interbreeding. This isn't a problem with self-pollinators like peas, beans, and tomatoes but can pose a real challenge with squash, spinach, or corn.
Isolation by Time
Some brassica family plants, like broccoli, are annual while others, like cauliflower , are biennial. This means that isolation between the two can be based on timing as broccoli will have long since made its seed before cauliflower flowers the following spring.
The same technique can be used if the time of flowering is different for two varieties of the same species because of differences in maturation rates. Orchestrating this sort of isolation would be somewhat delicate but certainly possible.
Another method for the farmer dedicated to saving seeds is to make use of the fact that many seeds retain their viability (ability to sprout and grow a healthy plant) for a number of years and therefore don't need to be grown for seed each year . Cucumber seeds, for example, will remain viable for at least five years if stored properly. You could grow a different variety of cucumber each year for three years and save the seed from each variety. Then, on the fourth year , grow the same variety that you grew the first year . That way you are maintaining the seeds for three different varieties of cucumbers without having to do anything exotic to keep the varieties from interbreeding.
Barrier isolation is the practice of using a physical barrier to keep flowers from one plant from pollinating another . The two methods most practiced are alternate-day caging and hand pollination.
Alternate-day caging is done by building cages out of fine window screen or floating row cover that will fit over the plants-two varieties of carrots, for example. On the first day, one variety is covered with a cage, and on the second day, the other variety is covered. This allows insects to pollinate both without cross pollinating them.
Hand pollination is easiest on plants with large flowers-like cucumbers and squash-but can be done on many other plants given a sufficiently steady hand. Hand pollination is made easy with members of the squash and cucumber family because of the fact that they grow large male and female flowers separately. A bag is used to protect the female flower from undesirable pollen until it is hand pollinated using a male flower of the farmer's choosing. The female flower is protected with a bag again until it is no longer receptive to pollen, and that fruit is marked for seed usage. If female flowers are caught before they first open, hand pollination can be very successful at maintaining purity even in instances where multiple varieties of the same species are grown.
Seeds that are naturally dry--such as those of spinach and wheat--are processed to separate the seeds from other plant materials by screening and winnowing. Screening is done with a screen selected for a mesh size that allows the seeds through but nothing larger .
(Southern Exposure Seed Exchange sells screens that are pre-sized for particular types of seeds.) This eliminates the larger debris.
Debris smaller than the seeds is removed by winnowing. Winnowing can be accomplished by pouring the seeds from one container to another in front of a stiff breeze or a fan. Lighter materials get blown away, and seeds get preserved. (Getting good at this takes practice!) Some dry seeds require threshing to be saved in appreciable quantities. Threshing is a technique that uses physical force to break away the pods surrounding the seeds and can be accomplished in a number of creative ways. Traditionally, farmers used a flail resembling a set of nunchakus for this task. The plants requiring threshing would be placed in a sturdy sack, and then the sack would be beaten with the flail and all the seeds would end up in the bottom of the bag. Another common technique is to place the plants to be threshed on a tarp, put another tarp on top so the plants are sandwiched in between, and then walk around on them.
Melons, winter squash, and green peppers are wet fruit, but their seeds can be saved like dry seeds by washing them in water to remove any traces of pulp and then drying before storage.
For plants whose seeds are embedded in damp flesh, studies have shown that the viability of the seeds is highest if the fruit is allowed to become a bit more than fully ripe before harvesting.
Such wet seeds will also benefit from fermentation processing. In fermentation processing, the seeds and pulp are scraped into a glass container--a clean pint jar for example-and about half that volume of tap water is added to the jar . Swirl and mix, then cover the container and put it in a warm place. Three days later , the contents of the container have grown a rather disgusting mold, and the good seeds have sunk to the bottom. The seeds that have sunk to the bottom are removed, washed, and dried.
Fermentation is not strictly necessary, but studies indicate that this sort of processing mimics natural processes and has been demonstrated to reduce the incidence of diseases in the seeds.
The length of time that seeds are viable depends on how you store them, and this applies to both purchased seeds and homegrown seeds. The two most important factors affecting the longevity of seeds are heat and moisture.
Studies have demonstrated that between the temperatures of 32 degrees F and 112 degrees F , the time that a seed is viable doubles for every 9 degrees F that the temperature is lowered.
The moisture content of the seeds is also important, as similar studies have shown that an increase in seed moisture of as little as 5% to 10% can reduce seed viability more rapidly than increasing the temperature from 68 degrees F to 104 degrees F .
(Seed banks store seeds in chest freezers at below-freezing temperatures. For home seed savers, storing seeds at temperatures below freezing is unusual because the moisture level of the seed must be carefully controlled to keep such cold temperatures from damaging the seed.)
Table 16: Seed Characteristics
Therefore, keep seeds cool and dry. This is easy to accomplish using moisture-indicating silica gel, small muslin bags like those used for spices, and mason jars with sealing tops. Moisture indicating silica gel and the small muslin bags can be purchased from the Southern Exposure Seed Exchange. When dry, moisture indicating silica gel is blue, and when damp it is pink. Once it becomes pink, put it on some aluminum foil on a pan in the oven on the lowest setting and gently heat it until it turns uniformly blue again. It can be reused indefinitely, so it's a good investment.
Place the seeds to be stored in a mason jar either within paper seed packets or not, because the seed packets pass moisture readily.
(You might do this with commercial seed packets you received in the mail, just to make sure they are properly dehydrated before storage.) Put two or three tablespoons of moisture-indicating silica gel in a drawstring muslin bag and put it in the jar with the seeds and seal. A week later , remove the bag containing silica gel from the jar , reseal, and place the jar in a cool basement or a refrigerator . If you use this method, your seeds should remain viable for a long time, and your investment in either purchased seeds or the personal effort of saving seeds is protected.