Seed info

– Posted in: Seeds and Seed Starting

various seed packets
Spring-like warmth and an absence of snow have conspired to create irresistible conditions for working outside in the garden. But not much beyond a little cleaning, mulching, and pruning can be done, as the soil is soaked and soggy and, as tempting as it is, it’s much too early to sow seeds outside. I’m channeling my gardening urges into planning the gardens and beds for this year and what seeds I would like to grow and/or need to realize the Versailles of my mind.

Seed catalogs have been piling up in neglected must-read piles for several months but I hadn’t the heart or inclination to attend to them until now. I am just as easily seduced by their pictures and descriptions of the newest and greatest as anyone and can see my garden flooded with their luscious colors and visions of Elysian Fields here on Earth. Or something like it.

Most of the generalist catalogs don’t offer clues to the originators of their seeds. How many of you know which seed companies developed Explorer Petunias, Majestic Giants Pansies, and Zowie! Yellow Flame Zinnia? If you said PanAmerican, Sakata, and Goldsmith you are either in the industry or unusually observant and informed.

So what goes into making all those beautiful plants in seed form available to us? My work in the flower department for a large wholesale seed company gained me invaluable seed sowing, germinating, and growing knowledge as well as an understanding of the research behind something as seemingly simple as a seed.

It all starts with the plant breeders. Their job is to develop proprietary plants that will improve on current lines in addition to creating new classes and colors of plants. Breeding goals include strengthening current lines as well as broadening their color ranges, disease resistance, weather tolerance, early and uniform germination, early to flower, uniformity of plant size, and floriferousness. Sometimes there are breakout developments. This is the case with the Explorer Petunias and the rest of the companies have been playing catch-up ever since.

The main customers for the seeds are plug and bedding plant growers and most of the seed producers gear their work to satisfying them and only incidentally the home gardener. The growth stages of seeds and seedlings have been divided into four sections. Stage 1 is when water, temperature, and light are manipulated to initiate activity within the seed, causing it to germinate and the seed coat to split. Stage 2 is the emergence of the root and seed leaves from the seed and the appearance of the seed leaves – also known as cotyledons – above the soil. Stage 3 is the growth of the seedling up to the point the first true leaf is formed. And stage 4 is the growing of the plant to a size it can be transplanted or sold.

Seed companies have devised several methods and techniques to aid the growers. Priming is a process of germinating the seed almost to the end of stage 1 but before the seed coat splits. The seed is held in a type of stasis, waiting for water and temperature to be added so it can continue growing. This helps the plug producers achieve quicker and more uniform germination in less than ideal conditions.

Detailing is the process of cleaning seeds so they can more easily be sown by mechanical means. A Marigold seed is a good example. If you look at an untreated seed you will notice a light colored “tail” on the end of the seed. Detailing removes the tail, making it easier to sow in a plug tray. Plug trays are usually always based on a design size of 10 x 20 inches and vary in the number of cells from as low as 50 up through 600. The tail of the Marigold seed gets hung up on the edges of the cells when the number of plugs per tray goes over 200.

All mechanical seeding machines (I sometimes jokingly call them “sowing machines”) that I’m aware of use an air vacuum to aid in sowing. Small portable machines will have interchangeable heads, called manifolds, with varying hole sizes and patterns depending on the type of seed and the number of cells per tray being used. I once used a manifold with holes too large for my seed and proceeded to suck all my seed away. Luckily the seed wasn’t too valuable or scarce and I was able to resow after changing manifolds. I ended up marking all of my manifold heads to insure my accident wasn’t repeated. Large stationary seeders don’t have plate-like manifolds but have small tubes that look like hollow needles to accurately place the seed in each cell of a tray. They dip down into a community trough of the desired seed and repetitively and quickly sow perfect trays.

These machines will also create a dibble, a slight depression in the middle of each cell prior to sowing, that helps to center the seed and slightly reduce the depth of the soil in each cell so a covering may be added if that is what is needed for the seed to germinate. Vermiculite was and is my preferred covering. Its advantages over a soil cover are: it remains friable but retains moisture, it comes in various size grades which is useful if many different size seeds are being sown, it has a strong color contrast with soil so its far easier to cover each seed with a precise layer, and some seeds like to be nestled in but not completely covered and I have never been able to achieve that with soil. I always used the last technique when germinating Primula seeds. I’m still not sure if it was essential but I did it with my first sowings, had great germination success, and continued using it.

Pelleted seed is now commonplace. This was done to aid the seeding machines. It achieves a uniform size and eliminates the irregular outlines of many types of seeds. It also allows for easy sowing of tiny and miniscule seed. The smallest seed I ever handled was Begonia seeds. They were dust-fine and impossible to sow mechanically in their raw state. I always broadcast sowed them in a flat. That worked fine but made for labor intensive transplanting.

The advantage to using plug trays with many small cells, besides the economic advantage of increasing the number of plants being grown in a specified space, is that seedlings grow quickest when their roots are tight. Zinnias were ready for transplanting 14 days after sowing and Pansies were always 21 days. The disadvantage of the trays was the need to maintain a proper moisture level. Most seeds in stage 1 need moist to wet conditions and then kept slightly drier from stages 2 through 4. Little cells, especially on the edges, can dry out quickly and you may lose some plants from inattentiveness. Overly wilted plants rarely come back strong and are perfect incubator hosts for pests and diseases.

In pure technical language, an F1 hybrid is the offspring from two plants that have been crossed. But the commonly accepted standard is an F1 hybrid is the offspring from two separate in-bred lines of plants. An in-bred line means plants that have been self-pollinated, seed collected and sown, and the plants grown to a stage they will flower and the process is repeated. Plants that show they are off-types or out of the standard being in-bred for are culled along the way. The goal is to get a genetically pure strain of the plant, where each member of every generation appears to be the same. The magic of an F1 is achieved when two plants from different in-bred lines are finally crossed to each other. The parents may be small and unassuming but the progeny are often spectacular. Most of this process of establishing the in-bred lines is time-consuming, labor intensive, and very expensive. There is a huge investment behind this work and is why some seeds seem outrageously expensive.

Breeding work is centered in Japan, the U.S., and Europe. The production of the F1 varieties is usually done where labor is cheap. This work is worldwide and is most common in Central and South America but I know of production areas in Africa, too. India and China will undoubtedly become major producers, as they have some of the cheapest labor on the planet.

Even I am getting tired of myself at this point, so I will finish with germination and growing guides. If I were working in the industry today, the Ball Culture Guide would be my constant companion. No matter what your knowledge level, if you follow the advice in this book you will achieve success. What seeds need darkness, kept uncovered and in darkness, have unusual germinating temperatures? This book has the answers. Its only drawback is it is limited to popular annuals, cutflowers, and vegetables. Thompson & Morgan have an on-line germination guide. It lacks detail but makes a good starting point. My favorite wholesale seed company is PanAmerican and I never worked for them. Click on “How to Grow Information” in their Product Information section of their site. I perfected my Aquilegia growing by following their advice. It also has the information in different languages. I don’t particularly like The Seed Site but maybe you will find it useful.

About the Author

I started in 1977 growing plants at wholesale nurseries and a wholesale seed company in California. In 1992 I started volunteering (in the nursery, of course!) at Strybing Arboretum in San Francisco where I met my wife. My wife is originally from upstate and we moved here in 2002. It took at least two years of living here for me to fully understand our property and to take advantage and work with our microclimate. Although growing zone maps show us to be in 5, we are realistically a 4b. I am inordinately proud, in a smarmy kind of way, of how many of the plants we brought with us have thrived. Coming from a zone 9 has been quite an adjustment for all of us. But we are thriving and enjoy the beauty and what the land gives us everyday. USDA Hardiness Zone: 4b/5a Location: rural; Central Leatherstocking near Cooperstown, New York Geographic type: riverine valley Soil type: Chenango alluvial – shallow clay and highly stony Experience level: 28 years professionally wholesale and retail, no longer in the business Particular interests: native plants and ecosystems, flowering and berry producing shrubs, home-grown foods, maples, birches, willows, ornamental grasses, filipendulas, iris, ligularias, persicarias, asclepias, artemisia, asters, arisaemas, hardy geraniums, euphorbias, eupatoriums, origanums, lysimachias, eryngiums, lilies, and visiting nurseries

Autumn is a second spring when every leaf is a flower.

~Albert Camus in Albert Camus quotations

Comments on this entry are closed.

Judy July 16, 2007, 8:36 am

Craig–Thank you for your excellent explanation and background about how some of the new hybrid flowers are developed. I have a question, though–If hybrids do not come true from seed (or even may be sterile?), why is it that we can purchase seeds for some–for example the ‘Zowie’ Zinnia–from such national suppliers as Stokes, Burpee and Parks. Will these seeds produce true ‘Zowies’ or will they be just ‘similar offspring’ with a range of ‘true-ness’?

I would like to learn a little more about how ‘triploids’, ‘diploids’ and ‘tetraploids’ play into new flower development, too, when you have time for another column on flower seed development!

Thanks again.

Hanna January 16, 2007, 12:06 pm

That was alot of fun to read. I always love the “inside” look at places and businesses that I wouldn’t have known about otherwise. Thanks!

Craig Levy January 11, 2007, 2:28 pm

Seed companies and plug growers are interested in germination percentage but their main concern is a concept called usable plug. Seeds sometimes germinate that are small, weak, underdeveloped, and slow to grow. They look like misses in a tray and are disqualified from being labeled a usable plug. Customers demand a full plug count and growers are perceived as poor quality suppliers if a tray isn’t full.

We had an entire Seed Physiology department dedicated to increasing and maintaining a high percentage of usable plugs. They were involved in the entire process from seed harvest and storage to constant 7 days a week workweeks germinating, growing out, and taking counts in 7, 14, and 21 day intervals for all trays.

They were responsible for developing and maintaining priming processes. I’m sorry that I used the word “stasis” – sounding too much like science-fiction as I reread it – but I don’t have the technical language to describe it properly but I think you understand the sense of what I mean. Priming is a proprietary process, considered a trade secret, and the details aren’t widely disseminated.

tom wagner January 10, 2007, 9:47 pm

“stasis” was a new word for me, I would like to see more articles on the handling of seeds. I am not a professional grower, but rather a small time gardener with time to putz around with seeds on a small scale, over the years I have invented some of the same techniques for misting plants, bottom heating, using timers, refrigerating seeds just like the big boys, but at a fraction of the cost or free.

Annie in Austin January 10, 2007, 5:47 pm

Thanks, Craig – I especially enjoyed the part about commercial seed-sowing.


Jenn January 10, 2007, 5:41 pm

Great post! Thanks!

beth January 10, 2007, 3:55 pm

As I’ve just licked the envelope on my Fedco seed order, I enjoyed reading this entry.
This past year we allowed our fields to grow wild rather than moving them. They are full of a wide range of ‘weeds'( I prefer to look at it all has habitat). In just one season I’ve noticed a good amount of plant variation within the same species-especially with the mallow.
Sublte shades of pinks and whites vary from plant to plant-it is easily noticeable. The ability to step outside my door and notice what goes on in the fields is one of the things I love most about living my rural life.

Carol January 9, 2007, 9:01 am

Great article on seeds. I think having background information like this makes us all better gardeners.