I'm the director of the Scatterseed Project in Industry, ME, a genetic conservation project, and I'm one of the directors and major curators of the Seed Savers Exchange in Decorah, IA. My experience is quite different from most of the others here because I'm used to curating very large numbers of varieties but relatively small numbers of plants and my objective is not to be cost effective for commercial production but to keep things alive.
There are two additional hoops that some crops require you to jump through-biennialism and issues of pollination control. Biennialism is a lifecycle trait that is intermediate between annualism and perennialism.
Perennials are usually very bioefficient, requiring very little in proportion to what they produce. Often they are climax species. Because they are very bioefficient and hardy often they don't have a great compulsion to make seed every year. Two examples are mints and jerusalem artichokes.
Annuals are usually short-lived, not very bioefficient. They tend to be band-aid species. They come in disturbed soil and cover it up until more efficient plants can come and are totally dependent on producing viable seed every growing season.
Biennials are annuals with a trick up their sleeves: they take one year producing a large vegetative mass, typically a taproot like a carrot or beet. Then that goes dormant for a year and in the second year they have the energy for a mad dash to make seed. A couple of implications for seed growers: 1)You have to invest resources in two consecutive years, a lot more effort than when you get it all in one year. 2) In between these two seasons you have a Maine winter which is relatively severe. There are complications in bringing these plants from one season to the next relatively unscathed.
Some species will overwinter fine in the field. Certainly
parsnips can overwinter right where they are and ought to. Salsifies
both black and white work very well. Chicories, especially the
witloof types, and those with good taproots, are generally well
adapted to staying in the field. Several that are very marginal
for me include parsley, the other types of chicories such as radicchios,
leeks and chard. You might be able to keep them in the field
with a light mulch or some form of protection. However, if you
try to rely on mulch for protection, you are often exacerbating
your risk from rodents, particularly in crops with taproots.
If you can keep them from freezing too many times and protect
them from rodents keeping them right in the ground is wonderful.
I can't usually get away with that. If you are mulching for protection
(I prefer maple leaves to straw or hay-they don't have seed that
attracts mice) leave the ground on either side of the area not
mulched at all, let it be bare. I like it to freeze solid and
deep. It makes it harder for creatures to burrow to get to your
plants. Don't mulch too soon-you don't want an advance build-up
of rodent population. Give them as little chance as you can.
A relatively small mulch-a half inch of shredded leaves-works
well. Lately with the light winters I've been putting a light
layer of wood chips on top, or little twigs just to hold the leaves
until snow keeps them down. With leeks I've tried to put up a
12-inch fence on either side and fill that up with leaves because
you want to keep as much of the leek top in place as you can.
Tom: You just mentioned that chard is one of the ones that's possible with some protection. Can you tell us more?
W: Kind of like the leeks. Maybe something around it with a little bit of depth to it. Use a fence or a good amount of mulch. Chard is a beet that has a taproot but not usually a nice round taproot, fairly hardy but needs a reasonable amount of protection. The top does not matter. No matter what you do, put it in the cellar or leave it out, the top is going to be trash by next spring. I think it best to leave the top on. The crown area where the earth meets the sky is the important part to protect. That's where the tissues that are going to turn into new tops next year are generated. The leaves and even quite a lot of the root are not important, the crown is sacred.
Q: What about straw?
W: I've used straw. It will work as long as it doesn't have seeds, but I prefer maple leaves. You need a reasonable mulch. Not even so much to keep the ground from freezing, but to keep it from freezing and thawing. Biennials are quite cold hardy. They are used to going through the winter in northern Europe or Mediterranean areas, just not in Maine.
Q: What if you only have the crown and you've lost the bottom of the root do you get less seed?
W: I've no experience with that but I'm sure you must. Second year root if anything is left will throw out little roots, but if you've lost the entire taproot that will hurt the yield. If your main purpose is to grow a commercial quantity of seed, then you won't want to mess with that root, you'll want ones where the root is intact.
Q: How deep a mulch do you recommend?
A: Of leaves, not a big thick mulch. A couple inches maybe. A bigger one makes conditions for decay, a thinner one protects it more.
W: When you have crops going to seed you're going to want to have them with a much larger spacing than for eating. Even if you overwinter them in the field you're going to be digging around and moving them in the spring. So that is not an advantage to leaving them in the field. You're going to disturb them either way. With the big lunky taproots like beets and rutabagas you're going to want to store them in the cellar. Over the years I've found quite a lot of difference in how well they store. Typically I will dig them up, cut their tops off, being very careful not to cut the crown
LOST a portion-tape eaten.
When you bring them up from the cellar or move them around in the field is a good time to make selection if you haven't already. You'll be discarding off-types-rejecting those that don't look as they should. My job is the opposite of a plant breeder, to keep the variety just as it is. If it seems to be part of the population I want to keep it in. If you're trying to improve it you'll be roguing. There's a swap between degree of roguing and seed yield. If you throw out 90% of the carrots, you won't get as much seed.
Spacing: With biennials you just can't imagine the difference
between first year and second year plant. Second year that modest
carrot can get to be two to three feet in either direction, four
or five feet tall. Some commercial growers figure four feet in
each direction for one rutabaga. In general I figure three feet
between rows. Within rows for leeks, onions and parsley I figure
one to two feet apart. Beets and carrots two to three feet apart
and rutabagas three feet.
Tom: Within the row radishes 6-8 inches apart and two rows to a bed-they hold each other up. Beets and carrots and chards the same. Will: That's closer than I do.
Will: I curate about 300 different radishes, some like daikons and Afghan winter radishes are giant. A lot of them are not dependable seed producers in our climate. I call them long season annuals. They are marginal and if you direct seed them you might not get a good seed crop. For that and other reasons I start my radishes indoors. I start them in 4-inch jiffy pots and thin to 3 or 4 plants per pot, trying to get at least two dozen plants just for genetic diversity (some people feel that is too few). I figure at least two feet per plant. I typically stake them. I do this will all the biennials, even leeks and onions. If I don't tie them up they tend to flop down.
There's a small group of crops, which while typically annuals, I find useful to treat as biennials or at least as long season annuals. Lettuce, endive and escarole I always start in trays. I like them to be good size when I set them out. For most lettuces it probably isn't necessary but I find that I get better yields. Lettuces, endives and escaroles have the advantage of being totally self-pollinated so I don't isolate them.
There are some special problems growing second year biennials that you normally don't see when you eat those crops the first year. In the first year, you see a certain amount, usually not objectionable, of alternaria blight. It is almost ubiquitous in organic carrots. In the second year it can be a very serious problem. Probably the fungal spores have overwintered and come out the next year for a double whammy. I'm the carrot curator and I'm not sure what to do about it. We grow carrots in cages so some of the problems people have in commercial scale carrots we don't even see. They cross with Queen Anne's Lace, feral carrot, and where in New England do you not have Queen Anne's Lace? A strategy is necessary to prevent contamination. Another problem with carrot is tarnished plant bug. Roberta: it gets the seed in the milk stage and reduces the germination to 70-75%. Will: The tarnished plant bug will get it when its almost mature and suck the life out of the plant. The seed will look good at a glance but when you come to clean it you'll find it is relatively light and fluffy and the germination will be abyssmal. I'm not sure how to deal with the tarnished plant bug organically. If I have it, I'm not aware of it. Roberta: I think the caging solves the problem. Will: But it is not the answer if you want to do it on a commercial scale. If you want to exclude insects from the environment you might be able to make the principle of it work by making a giant cage. I think if I wanted to do carrots on a commercial scale, and I haven't done this, I would make some hoops and a big row cover arrangement until they got pretty big. I'd use Elmer's Plantex as opposed to reemay because reemay has a greenhouse effect of at least 4 degrees. For some of these crops you don't want that extra heat. One of the problems with cages was the umbels, especially the primary, rubbed right up against the screen. I was using rigid wooden cages with aluminum screening. I was afraid the pollinators would get in there so I had to break off the umbels that were touching the screens, which were some of the best ones.
It is important to get things out of the cellar and into the ground as early as possible. Some are very short cool season varieties. Radishes are quick to flower but once they bolt it is surprising and discouraging how long it can take them to flower, form a pod and for those pods to ripen. Leeks I want to get out very very early because even though they start bolting quickly, even when the flower goes by it takes a long time for the seed to mature. Usually there's snow on the ground when I finally pull them. Some of them are lying on the ground, broken open, but that's okay because leeks won't shatter. (It won't work with onions which shatter all over the place.) Then I clip them off, bring them in, the whole things upside down in big paper shopping bags, and I put them in the floor of the office of a warm heated room and still leave them there for a couple of weeks. Leeks need a long time of after-ripening, even more than squash.
Pollination control: Not all species need pollination control. Usually it is something in the morphology of the blossom, the shape of the petal, that protects the ovary until the flower has pollinated itself. In a case like that you don't have to do anything, you don't have to isolate. Beans, peas and lettuces are all self-pollinated species. Tomatoes are generally self-pollinating, the big exception is the potato leaf varieties because of the way the stigmas stick up in the air. Oats, barley and wheat are self-pollinating. Every year we grow about 300 varieties of peas all in one single garden. All the biennials are cross-pollinators.
The first and simplest strategy and perhaps the only one for those wishing to grow commercial quantities of cross pollinators is isolating by distance. The first question that come up is: What distance? I can't give you numbers. I can give you some factors and ranges of numbers. Factors: What is the pollinating vector? Bumblebees will travel a lot further than syrphids. If beets or spinach, which are wind-pollinated, you might need a lot more isolation. Prevailing wind direction might be a factor. Factors that are mentioned that are not very significant are hedgerows, woods, what's in between the plantings. I've always been told that plantings of buckwheat or clover between the carrots make it safer. The theory is bumblebees will visit one patch, then the clover, then go to the hive, by the time they get to the other patch the pollen is rubbed off. It may not work that way. They may tend to go to one crop at a time.
The biggest factor is: What is your priority? How absolutely essential to you is it to have this degree of purity? If you grow seed for your own use in your garden you might say 80% is okay. I can live with 20% crossing and so its okay to put them 50-100 feet apart. The other extreme if you have to have absolute purity you should have one plot in Venus and the other on Mars! Somewhere in between is what you figure out. Generally 500-1000 feet will suffice, but it depends on who you are selling to. Some people would require a mile or two. I figure a minimum of 300 feet, with some being more. It's a bit close, I could get some crossing. I'm torn between the need to have some purity and the difficulty of having a lot of isolations and a lot of varieties I need to maintain. If I need to grow out 30 or 40 different varieties of radishes each year, I have to find somewhere on this bell curve where I can get a maximum number of isolations with an acceptable level of purity. I'm not seeing a significant level of crossing at the distances I'm using, and some of the varieties are sufficiently different that it would show up. If I were to put them twice as far apart, I would have a greater level of statistical purity but only a fourth as many isolations and that means I would have decided with 75% of our collection in some cases which ones were going to become extinct. For some of the varieties we are the last place on Earth where they are being grown. Maybe this parsnip has been grown for centuries in Chechnya but its native village has been bombed out of existence and the people are either dead or gone and no one else is maintaining it. So I can't be too hairsplitting about .5% crossing at this distance. For commercial production you'd want to go to larger distances than mine if you could. The simplest thing of all is to just do one variety of each species.
A species is defined as a community of plants which will pollinate themselves. If they can't have sex and make babies successfully (viable seed) then they are a different species. If you know what species you're dealing with it helps a lot. If you know that beets are beta vulgaris and chards are beta vulgaris then you know that beets are chard and chard are beets, they are the same species and you can't have the two of them growing in proximity or they will cross. (The sub-species names are meaningless botanically). That's why Linnaeus came up with his classification system.
On the other hand, consider what is loosely named the cabbage family, brassica oleracea. We see them as a whole bunch of different things because we use them differently, but they don't see themselves that way. They are botanical monstrosities with the same ancestorwild sea kale which grows wild even today on the shores of the Baltic facing the North Sea. It is the ancestor of cabbage, kale, collards, brussels sprouts, kohlrabi, broccoli and cauliflower. Those are all one specie, so don't think you're going to save cauliflower and cabbage seed in the same plot. They will cross with each other.
You need to know that true turnips are brassica rapa. They won't cross with cabbage. They are distantly related but can be in the same plot no problem. Rutabagas, brassica napus brassica, won't cross with either of these two. Rutabagas are a specie that doesn't exist in the wild, an artificial synthetic specie which came into existence in the Baltic area probably pre-1600. Likely it arose as an interspecific hybrid, a rare fluke, a cross between different species. Its parents are believed to have been the true turnip from Central Asia and wild sea kale. The cross probably happened in a farmer's field in Estonia. Rutabaga is descended from these parents, having a chromosome # of 27, halfway between the 18 and 36 chromosome numbers of the parents. All three can be grown together, despite their funny relationship with each other. They won't cross-pollinate.
Separation by time within a season: It works somewhat but I don't recommend it as a practical strategy. It is really risky. You can sometimes get away with it, especially for your own use, say putting in an early-maturing and a late-maturing corn. In Maine you often can't separate those enough in time to avoid some overlap of the flowering period. One way is to mark the skins of the true ones that didn't cross. Too complicated for commercial production.
The other version of separation by time is alternating seasons. If you grow a big crop of beet (a several year supply) one year and next year grow only chard, it will work. In the interim year you can put the beet seeds in the deep freeze to keep viability up.
I'm not sure caging is relevant for commercial production. The problem is scale. On a smaller scale it can solve several problems at the same time: deer and insects. Cages have the additional advantage of making it a little bit cooler which is good for brassicas. I made a bunch of cages one year with rigid wooden frames covered with aluminum screening. Worked really well except they were small for carrots. The carrots blossomed and pushed against the sides. My big problem was I couldn't knock them down and store them away for the winter, it wasn't convenient to cover them up, so they stayed outside and the combination of the snow and wind blowing around splintered them apart.
Q: How about PVC?
A: I'm going to try that next time.
One of the problems with any of the things I've tried (wire hoops, not intelligibleis better than reemaybut worse about not snaggingany kind of a nail head or corner is a problem.
With our huge 90x25 ft. fava bean tent under one big sheet of --__________, there's nothing separating them (50-60 varieties) from each other, nor does there need to be, as long as they're separated from the environment. Unlike carrots which can cross-pollinate but individual flowers are self-sterile, runner beans and fava beans can cross-pollinate but are also self-fertile. If I have them in an environment with no vectors at all they won't cross-pollinate but they will self-pollinate. The complications with that: 1) For runner beans if you don't have bumblebees knocking the blossoms you'll need something mechanical to jostle the flowers at least once in a while and 2) I just learned from Larry Robertson that if you don't have any insect wreckers at all, yes they self, but you end up getting a pureline selection and they (favas) should be cross-pollinating within a variety to maintain their diversity.
Our runner bean screen, 24x24' X 8' tall, is covered with aluminum or nylon screen on the side and on the top with chicken wire with reemay setting on it. We have 7 rows each of 7 poles so we can have 49 varieties of runner beans. Runner beans are hard and I'm trying to get the varieties I'm failing on into the National Germplasm System.
Carrots: Because carrots and most of these biennials are self-sterile, it isn't sufficient to remove the bugs. These plants, even though their blossoms are perfect flowers (boy and girl parts in the same flower), won't accept their own pollen. Brassicas are also very much this way. This is nature's way of preventing inbreeding depression. Nature is saying "you're too close to self-pollinate." Allowing it would undo the very purpose for which sex exists (I know you think it's for selling aftershave lotion!). The real reason is maintaining diversity for abaptability so creatures can respond to the various challenges nature throws at them. Sex is one of the great ways to do that, a way of retesting various possibilities in ever-changing configurations.
So we're trying to do two things at the same time: to keep plants of this variety from being pollinated by another variety and to guarantee that they will pollinate within the variety. We need either insects or manual labor. A paintbrush can be used to move pollen from here to there. Sometimes plant breeders will use Q-tips to move the pollen, but that is not efficient in a commercial field.
At Geneva they either use nukes (each cage has its own hive) or introduce bees. I'm dealing with 30-40 tough species, a lot of them biennials with different preferred vectors. The brassicas prefer honeybees. The umbelliferae really prefer syrphid wasps, the hover flies. Others prefer this, others that. I have two options. One is to send away to insectiaries to get this&this&this, pretty expensive and complicated. The other is to find a schmoo vector: One insect fits all. Surprisingly, one of the most promiscuous pollinators is the housefly. I send for them to a place in California where for a $25 money order, they send back 1,500 fly maggots, 2nd day air, timed to be hatching out the day they arrive. It is the cheapest way to go. They are not the best vector for any single specie I do, but they are the best for all of them. I put a couple dozen maggots in each cage and put a little molasses in a dixie cup to get them going. I've done it only with carrots but the principle applies to all the species.
For the insect pollinating crossers, all that matters is that you don't allow a bug to get in. Pollen isn't going anywhere unless a bug takes it. Beets, chard and spinach have a very fine pollen that is wind borne. You need a fine mesh. People use reemay or typar.
A strategy that works with squash but not many others is hand-pollinating. Here knowing species is important. The word squash is too encompassing. It includes three different species that won't cross with each other. Maxima (all large warty-fruited winter squashes, leaves round and entire, spongy corky stems biggest in the middle and smallest at the ends.), Pepo (a large, varied group including all the summer squashes and true pumpkins, spaghetti, delicata, acorn squashes, very sharp angular leaves, deeply lobed like a grape leaf. All pepo fruits have a skinny, hard spiny stem which enlarges as it gets toward the fruit.) and Moschata (butternuts and cheeses). You can grow zucchini and buttercup in the same garden with no crossing.
If you must grow two pepos and keep them pure one of the simplest ways is hand-pollinating. You have to know the female flowers from the males because squash has monecious flowers (both males and females on the same plant) but they are separate blossoms. The male has a long succulent stem. The female has a shorter stem with a bulge. This is a virgin ovary. Males tend to form first and after a while the females kick in and then they are present at the same time. They are ephemeral, good only for one day, you'll have to know on this day you'll have a male and female ready at the same time. It is not critical that the flowers be on different plants, though ideal if they are. Inbreeding depression in the short term is not a big factor in squash. The day before the blossoms open, they show yellow and are starting to rupture. Find the ones that will open the next day, bag them, tie them so no bee can get in. At the same time, look around for the ones you bagged the day before, take those bags off. Break off the male and take it to the female. (Missed a few lines)
Circumsize them. Male flower shiny glistening smooth bright yellow thing. Next day it is covered with downy fluff which is pollen. Happens within 24 hours.You want to be sure to get the pollen all over, all around the side. This plant isn't growing this fruit for you to eat. It is growing it to nourish its seed. The plant isn't going to use all its energy for just a few seeds so if you don't do a good job, the fruits are likely to be curved and misshapen. If there is really too little pollination, it will abort. Some people put the bags back on. If you've done a poor job, this won't help. Only reason is to make sure there will be no further pollination. Then you mark the plant by making a little crack with a safety pin in the skin of the ovary so you can tell it from the fruits you don't want which will otherwise look the same. As it grows, the mark will become more visible.