You missed one more very important criteria -- where their seeds come from. Most of the big names seem to have seed that is better adapted to the cooler, northern climes. The southern gardeners -- whether they are hot and humid, or hot and dry have different needs in a variety than cool, short seasoned northeners. Generally, seeds that are grown in a clime similar to yours will do better.
The first thing I look at in a seed catalog, is where is the home company located. Living here in Texas, if it is north of the Mason-Dixon line, then I look to see if they identify where the seed was developed. If they don't at least give some hints, or all of their hints point north, then in the trash it goes. (Note: When I lived north of the Mason-Dixon line, I would look at southern seeds and dream of home, but ordered from northern companies.)
Experimenting with 'out-of-range' seeds can be fun, and occasionally you will find a real treasure. However, IMO, they should be exactly that -- experiments, and not your base plantings.
A word of caution. All the major vendors buy thier seeds from Development companies. A high percentage is not even grown in the USA. Seeds to day are very international. A given variety, whether sold by Willhite, Johnny's, Twilley or Burpee likely had the same origen. I buy a lot from Twilley, because they are close by and cater to southeastern market gardeners. But I also buy from Johnny's and New England Seed and other northern vendors with no problems. Surprisingly New England Seed is my best source for short day onions. Shumway for several year was located 11 miles from me. Most of thier seeds came from Seeds by Design ( a California producer). They moved to Wisconsin and still use the same source. Your best bet is always to select varieties that tested well in your area.
What you say about the importance of where seeds comes from sounds sensible. But aside from anecdotal evidence, do we really know aside from what Darwin said about the survival of the fittest? I just don't know.
I feel more certain that buying "organic" seeds only benefits the seller. Seeds don't carry pesticides.
From personal experience, yes, I know, and I wasn't on an organic soap box.
Watermelons are an excellent example. If you want to grow watermelons in the north, you need a small, fast growing variety. In the coastal south you can grow the huge, long maturing black diamonds. The black diamonds really want sandy soil and pout in even heavily amended clays. In drier areas (like where I live in the caliche black lands east of San Antonio), a medium sized, black-land adapted melon is usually the most productive.
Seed companies grow their seeds where they can get the best production of that seed. If you grow them in a similar conditions, you will get the best production.
That is the ideal. Vegetables for the most part are annuals and so with the right care, they will do 'something' in most areas. You are most likely to get great 'somethings' with plants that like growing in your conditions.
It isn't an absolute. It is a way to hedge your bets.
That is true. Variety counts.But if you want to grow Black Diamond, it does not matter whether you buy the seeds from Wilhite (Texas) or Shumway( Wisconsin). A popular hybrid like Sangria is produced under controlled conditions by a licenced breeder. Even less chance of variability among vendors than an open pollinated variety like Black Diamond. The big commercial growers buy thier directly from Seminis, Syngenta, Takaii, Sakata, Ugen, Golden Valley etc. smaller operators will use commercial vendors like Johnny's, Osbourn, Clifton, Rupp, etc. The home garden venders just buy seeds form the biggies and repackage them in small lots.
"You mention about the seeds coming from China. The company I used to work for bought every seed in from a lot of the big name suppliers: Seminis/Monsanto, Rupp, Seeds by Design, Ball, Charter, Takii, etc. Our computerized seed database was set up so that you could look back and see all the information on past lots back to about 1990 or so. There were many varieties that would have “US” or a state abbreviation listed up until about latter 2000s and then it would be CH (China), TH (Thailand), VT (Vietnam), or a generic SA (Southeast Asia) for more recent lots.
In general, it seemed like the only things produced in the USA with any frequency was beans or items that came in from Seed Savers Exchange — however, Aaron Whaley and the folks at Seed Savers do have a lot of their seed grown in South America during our winter months. Also, some of the Seeds by Design came from the USA, but I do not recommend them because their seed has LOTS of purity issues. Any Solanaceae member came from China (a few peppers from South America). Greens and cole crops usually came from China, although some of the ‘fancier’ greens came from Europe. Melons and cukes were coming steadily from Asia for a lot longer than the 2000s. Corn was still coming in from the USA, but it seemed that each year there would be 1 or 2 more varieties that would come in from China.
As for it all coming from one place, there is more truth to that than you could imagine. Even when different seed suppliers offer the same variety, the paper work you receive when you buy it reflects that both companies had it grown by the same seed producing farm. 9 times out of 10, no matter where you buy your seed, the seed companies will have purchased their bulk seed from the same seed supplier. The differences come in with what the seed catalog company does with it once they get it — (1) how long the company has had the seed sitting on the shelf, (2) what conditions it was stored at while in the bulk bag, (3) what types of insects may have been in it while it sat there, (4) if it suffered any damage from the packeting equipment, (5) what conditions it was in after it was put in the seed packet, (6) how frequently they are checking germination and quality tests so bad lots are pulled before being sold (by law should be every 6 months), and (7) if the old packets from the previous year were dumped back in the bulk bag and repackaged for the next year (no kidding! It is against the law to do this, but many companies are sneaky and do it to save money).
It’s scary to think that the seed is coming from locations that do not have as strict of standards when it comes to how the plants are grown. Chemicals that we have banned here are not necessarily banned in these other countries. That, among other scientific and moral issues I had with the seed industry, is a huge reason for why I left the my position and branched out into starting my own horticultural consulting and organically-grown heirloom seed company.
If you are looking for any new catalogs to add to your list, I highly recommend Baker Creek Seeds in Mansfield, MO, and Seed Savers Exchange in Decorah, IA.
I like to use a Dave's Garden Watch Dog member recommended seed order catalog that has the product that I am looking for and usually along the way I find a few more things in the catalogs that I think I need. Then, sometimes when I rationalize what the cost of shipping and handling, it is not worth ordering. I have recently placed orders for those HARD-TO-FIND items that I cannot find elsewhere.
I try to find vendors who grow their own seeds or know their growers all around the country like Fedco, Heirloomseeds.com, and Tatiana's TOMATObase, where the tomato seeds she sells are often her own or she lists reliable vendors. Garden Watchdog has been like a Bible and extremely useful. The internet has made it possible for home growers to advertise their wares and Garden Watchdog helps with the evaluation as to the quality of their products and service. I steer clear of the really big vendors since you don't know where the specific items originated. Recommendations from members of groups like Dave's Garden are invaluable in helping assess reliability and quality.
I use Garden Watchdog probably more for for potted plants than seeds and find it helpful in determining whether the plants sent are correct and in good health. Customer service is extremely important to me as well.
While one must, of course, evaluate the complaints as to relevancy or whether the complainer is an experienced gardener, many people do report on germination rates they encounter from companies. If there are a number of serious complaints, then I look twice at that site. And you are probably correct that there may not be scientific evidence that seeds bought locally are better or worse than those from bigger companies. I am not as concerned about local as much as the smaller, family owned companies. I do feel better buying from them even if it is more emotional. Any company can experience errors in packaging. But my last bad experience was with Burpee where my Sugar Daddy Peas were definitely not what they were supposed to be so I went with a lesser known, family owned company called Heirloom Seeds this year. Time will tell if these are correct!
I'm curious about the seeds I get from Seeds From Italy. I know the EU is very strict about their seeds and I've felt I can trust them. I'm just a home gardener but I've had good luck with their seeds. I normally buy from Willlhite's, Victory Seeds, or Southern Exposure Seed Exchange. These have all been recommended to me by gardeners here on Dave's. And I do use Garden Watchdog just to check up. Now I'm kind of wondering about the seed producers providing "European" seeds to the companies like Seeds form Italy and Italian Seed and Tool, etc.
Usually these are seeds from major Italian distributors. Pagano, Franchi Sementi, Bavicchi. The European system is a liitle different. In the US seed is tested for germination usually in December for package as label for a given year. Europeans put tested seed in a sealed package. Fresh when they go in the package, but no sell by on the package.