Seeds forum: Best single source (book/web/app) for when & how to plant seeds?

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danjcla
Mar 22, 2018 2:16 PM CST
UPDATE: So far the best sites I've found are below. I really hope there is a book or app I'm missing, because they are all kind of basic and none answer all my below questions, although major kudos to their owners:
* Rob's Plants seed germination: http://www.robsplants.com/seed...
* Tim Clothier: http://tomclothier.hort.net/in...
* The Seed Site UK: http://theseedsite.co.uk/db1.h...
* Dave's Garden "When to sow advice" user spreadsheet: https://docs.google.com/spread...

I'm looking for a recommendation from an experienced gardener on the best single source - book or web or even app, I don't care - for when and how to plant seeds. Ideally each plant would have an identical, chart-like, well-laid-out page that would make it easy to determine for each Zone (or only Zone 6) based on both temperatures and estimated frost dates.

Or, even better, I could just enter my list of seeds and location, and it would compute all this for me and present me with optimal answers for my specific location, integrated and updated with weather forecasts.

All of these items for Indoor, Outdoor/Fall, Outdoor/Spring

1. The degree to which Indoor+Transplant vs. Outdoor/Fall vs. Outdoor/Spring is preferable
2. Seed stratification start time range and methods - optimal & limits
3. Seed sowing time - optimal & limits - how bad is it if it gets below a certain temp / frost?
4. (for Indoor) Transplant time - optimal & limits

My problem is that a lot of the packets and sites are both mutually- and self-contradictory and don't do a good job of specifying what exactly they mean.

For example, one seed packets suggests sowing "2-4 weeks before average last frost or late fall, cooler soil temps are preferred (55F). Stratification is recommended." Leading to questions the ideal source I am searching for would make clear such as:

1.What does 55F mean - some statistical function of high and/or low temperatures over some time span, average soil temperature at some unspecified depth (does any weather site actually provide this info?), something else?
2. Does "55F is preferred" mean the plant will do a lot better when you plant the seed at this temp, or if you plant it earlier will it just wait until it's more around 55F?
3. Why the hell would it suggest planting the seed 2-4 weeks before last frost, when temps are in the range of say 24F-40F, right before stating this is really non-optimal.
4. What are the cases when you need to do stratification? I'm guessing you wouldn't need to if planted 2-4 weeks before average last frost but would if freezing temps are no longer happening, but it doesn't state this.
5. What is the recommended stratification method?

Thanks! :-)
Name: Larry
Enterprise, Al. 36330 (Zone 8b)
Composter Garden Photography Million Pollinator Garden Challenge Garden Ideas: Master Level Plant Identifier Celebrating Gardening: 2015
Region: Alabama
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Seedfork
Mar 22, 2018 4:37 PM CST
Let me try to answer some of this:
Just use a soil thermometer and stick it in the ground and take the temp, the soil temp should not vary as much as air temperature.
I think two to four weeks before "average" frost date is the key, and that I think answers the stratification suggestion. You might get cold enough temps for stratification and you might have enough moisture in the soil for stratification to take place, but these are averages and you might not. So it seems they are just trying to cover some variables.
Naturally all the info you need can't be presented on a seed packet. Nor do I think any one source will ever answer all of a gardeners questions, heck dozens of books will never tell you everything you need to know.
But for free check Dave's app here on NGA . Look under Apps, then punch in your zip code, it will give you average frost dates, then under the fall frost dates click on the Garden Planning Calendar for your City. That will pull up a list of some suggested crops, then you can click on each of them for more info. No, it will not answer all or even most of your questions but it will give you a lot of good info and a general feel for growing crops in your area. One thing I have found in gardening, almost nothing follows a schedule you can count on, and for almost every recommendation you can find you can find someone not recommending it.
[Last edited by Seedfork - Mar 22, 2018 8:17 PM (+)]
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Name: Rick R.
near Minneapolis, MN, USA zon
I was one of the first 300 contributors to the plant database! Garden Sages The WITWIT Badge Garden Photography Region: Minnesota Hybridizer
Seed Starter Plant Identifier Million Pollinator Garden Challenge
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Leftwood
Mar 23, 2018 9:15 AM CST
If you find such a holy grail, be sure to let the rest of us know!
Obviously, there are better and worse lists/compilations, trustworthy and not so much so, more and less complete. There is no list that even nears the completion that you wish.

Your frustrations are understandable, but not well deserved. Sometimes the answer just isn't known. Before the internet, the only way to pass along such information was via land line telephone, post mail or on the ground manual research in libraries. Such published detailed information was scarce and incomprehensive. The sources usually being university based scientific papers, accessible only in a particular library(s) somewhere in the world. I find it incredible that there is even any moneys that are dedicated to this kind of research, and I am grateful. It's taken a long time to get to where we are now. The web is a wonderful thing, and it is an extension of all these prior processes. The web is an incarnation a thousand times more efficient that anything previous, and is still only as good as those who contribute. I too, get frustrated when information is incomplete. My point is, that at least something is there at all.

As you learn about about seed germination, you will discover that your initial frustrations are not as important as you had thought: mother nature is always a continuum and there are rarely cutthroat rules. I always say that in nature, the only unbroken rule is that there are no unbroken rules. The more you learn, the more you find out that there are even more things you don't know.

I am always on the lookout for such information as close to scientifically rendered as possible: when environmental parameters are clearly delineated, as well as the results. This rarely happens to any large scale, and often our only sources are relatively useless anecdotal information.

Statements like "Seed germinated at room temperature for me". Depending on the source, it is more or less believable and more or less could be read into it or assumed. Is it reasonable to assume that the seeds were viable to begin with? We don't know how the seed was stored prior, how many seeds were involved, the percentage of seeds that actually germinated, was sterile-pasteurized-unpasteurized soil used, was it inside or outside, etc. We don't even know (we just assume) that "germination" also included sprouting above the media surface. But for empirical data collecting, what can you actually gain unequivocally from this?
-- that seed might germinate and emerge at room temp. That's all.

To your original questions, if you don't know about Dr. Deno's books, then you haven't read "The Ultimate Resource for Seed Collectors". It uses scientifically based data for actual germination of more than 4800 species. A consolidated info spreadsheet is found here: https://garden.org/thread/view...

1.What does 55F mean - some statistical function of high and/or low temperatures over some time span, average soil temperature at some unspecified depth (does any weather site actually provide this info?), something else?

-- If the data is for indoors, it is fairly safe to assume it is the ambient seed temperature, i.e. whatever the media is that the seed is in. Even then, there are variables. If it is under lights and covered with clear plastic, you can add another 5-15°F to the room's temp, and realize that when the lights are off the temp will be whatever is ambient.
__ If it is outside, what is meant can be a crap shoot. Unless specified, I suppose I would assume air temp, which depending on the time of season, one might be able to extrapolate the temperature of the soil. The soil temp is rarely the temp of the air.

2. Does "55F is preferred" mean the plant will do a lot better when you plant the seed at this temp, or if you plant it earlier will it just wait until it's more around 55F?
-- We can assume that the seed will sprout better at around 55°F. A lot better? unknown. I would expect it to germinate slower at 50 and faster at 60. Whether the particular type of seed will germinate much above or much below these temps is unknown. This answered, tempered with the above (#1) explanation.

** ** ** ** ** ** ** **
There are always exceptions, but a generalization for seeds is that most fall into a two groups for ACTUAL SEED GERMINATION temperature:
Around 40°F - range from above freezing to about 50°F
Around 70°F - range above 60°F
** ** ** ** ** ** ** **

3. Why the hell would it suggest planting the seed 2-4 weeks before last frost, when temps are in the range of say 24F-40F, right before stating this is really non-optimal.
Many kinds of seed need a preconditioning that is different from the conditions needed for when actual germination occurs

4. What are the cases when you need to do stratification? I'm guessing you wouldn't need to if planted 2-4 weeks before average last frost but would if freezing temps are no longer happening, but it doesn't state this.
The cases are many and variable, depending particular seed types. You will only know through research. Some might need a cold stratification for 2 weeks, some might be 4 months. Some might need multiple cycles and cold and warm at certain durations. About the only real generalization is that there are a greater percentage of wood plant seed that need cold stratification than non-woody.

5. What is the recommended stratification method?
Assuming you mean cold stratification, anything that gives 33-45°F with moisture and air. People usually do this in a pot, jar or baggie with moist peat, sphagnum, vermiculite or a light soil media. You cannot submerge or float the seeds in water for stratification.
Name: Maggie
Calaveras County, CA (Zone 8a)
Region: California Winter Sowing Vegetable Grower Seed Starter Enjoys or suffers hot summers
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Faerygardener
Mar 23, 2018 11:56 AM CST
Ok, you have Tom Clothier's, which is one of the best out there.

Additionally, I like Johnny's Seed Starting Calculator - but I play with it. We can have a long cold damp spring where the soil doesn't warm but no hard frost. So, I know I want my "planting out" date for tomatoes to be May 1st, the calculator says plant them out one to 2 weeks after the last frost date - so I plug April 15th as my frost date into the calendar and use it from there. It's veggies and common flowers, but if you're not growing highly unusual items, you can extrapolate (e.g. all tender annuals could be planted a week after frost free date, hardy annuals 2 weeks before) http://www.johnnyseeds.com/gro....

Soil temps - for tomatoes that usually want soil temps of at least 55°, the recommendation is: "Tomato plants can be transplanted at GROUND Temperature of 55 degrees F, but growth will be slow. Use a rule of thumb of a night air temperature minimum of 55 degrees F". http://articles.extension.org/....

Another good site with more unusual offerings is J.L. Hudson http://www.jlhudsonseeds.net, although he has notations (chill 2 weeks, nick seed, days to germination) I don't see temps on the website now - perhaps they're still in his catalog.
Remember, it is dangerous to the environment and ILLEGAL in MANY states to mail plants/bulbs/cuttings in. Let’s all practice Do No Harm while we walk this earth and find other ways to connect to one another through gardening.
Name: Bonnie
Chandler, AZ (Zone 9b)
Region: Arizona Bee Lover Butterflies Hummingbirder Xeriscape Birds
Seed Starter Winter Sowing
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droughttolerant
Apr 28, 2018 7:00 AM CST
My favorite go to book is The Gardnener's A-Z Guide to Growing Flowers from Seed to Bloom by Eileen Powell. Been using it without fail for years and years. It doesn't matter where you grow, there is info to follow for you for each seed, like when to sow indoors or when to sow outdoors. She gives info based on seed needs, not specific regions. You wait until your climate is at the right indicators for the seeds you wish to sow and sow away. The first section of the book is all about different methods of see sowing. Everything you need is in there. There are pictures as well, in one section for identification. It is my favorite book on the subject.

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