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

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! :-)

danjcla
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Joined: Thu Mar 22, 2018 2:45 pm

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: https://www.robsplants.com/seed/germination.php
* Tim Clothier: https://tomclothier.hort.net/index.html
* The Seed Site UK: https://theseedsite.co.uk/db1.html
* Dave's Garden "When to sow advice" user spreadsheet: https://docs.google.com/spreadsheets/d/ ... sp=sharing

danjcla
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imafan26
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Location: Hawaii, zone 12a 587 ft elev.

I think it really depends on where you live and what you are planting. No matter what zone you live in, there may still be variations in microclimate depending on your elevation and whether you are in a valley or near the ocean. I find temperature to be a better indicator than planting dates. Especially now, with the weather being so screwy in recent years. It is possible to get a freeze just when you think things are starting to warm up.

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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

I’m inclined to agree. There are many variations in local climate — even my own little postage stamp garden between south side and north side of the house, how the garden was prepared, is being maintained/cared for, .... etc.

It’s not just usda zone but average last and first frost, and daily high and low temps, and precipitation ... I would be amazed if a single site was able to automatically compute and supply information for specific plants while taking into account all of that — it would require fuzzy logic.

Gardening really requires that you chart your own data based on probable, attempted, and actual results over a number of years. Many of us keep a gardening journal ...or acknowledge that we should. :>

... Not to toot our own, but the many conciencious and enthusiastic minds here at Helpfulgardener might be able to provide a more individualized real-time response because we could ask for details you forgot to specify.... or, of course, you could search our archives for relevant information because it’s very likely that our chatty members have discussed the very same question sometime in the past :wink:

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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

You didn’t really provide key info, but generally speaking —
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.
...I recognize this scenario as starting seeds indoors under preferred conditions for germination and seedling growing, so you would have started plants to plant out at optimum planting time (after properly acclimating them to the outside conditions, of course)

The 2-4 week timeframe takes into account that, without the optimum conditions, seeds may take longer to germinate and sprout — as much as 2 weeks (or more) whereas under optimum conditions, they might sprout within a few days.

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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

Stratification method and time period depends on the plant.... What are you planting?



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