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Best single source book/web/app on when & how to plant seeds

Posted: Thu Mar 22, 2018 7:06 pm
by danjcla
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! :-)

Re: Best single source book/web/app on when & how to plant s

Posted: Thu Mar 22, 2018 8:20 pm
by danjcla
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 questions, although major kudos to their owners:
* Rob's Plants seed germination: http://www.robsplants.com/seed/germination.php
* Tim Clothier: http://tomclothier.hort.net/index.html
* The Seed Site UK: http://theseedsite.co.uk/db1.html
* Dave's Garden "When to sow advice" user spreadsheet: https://docs.google.com/spreadsheets/d/ ... sp=sharing