lereg15 said: ... Do you think that the germination times will be slower because of my temperature, or will they be fine? ...
Every crop and every variety of each crop is different in their tolerance for cold weather. So unfortunately, "it depends". I'm still hoping someone local to you chimes in, because I don't know your weather.
Even then, if you have a seed packet that says "very cold-tolerant", you might be able to plant earlier than your neighbors. If your slope and exposure give you a warmer or colder micro-climate, you'll have to tweak even a neighbor's advice to match your garden. (Or relocate some beds!)
My rule of thumb is to really coddle warmth-loving crops like tomatoes, peppers and eggplants, because where I live, it barely EVER gets warm enough for them. For those 'warm crops", planting too early outdoors would be a risk, and seeds of warmth-loving crops
planted a little later will often catch up to or surpass ones planted "too early".
Generally, if there is a pinch between:
"how soon can I put them in the ground?"
and
"darn it, my short season meant that the late-planted rows never had time to fully mature"
...
then you would have been smart to set up a light shelf and start at least SOME seeds indoors for later transplanting into settled warm weather.
The really smart move is to start a few indoors, and direct-sow a few 2-3 weeks before you think is ideal. Maybe dedicate one row to 'exper8iments" and sow a few feet of each crop you are wondering about EARLY. Then sow most of your seeds whenever you think is probably pretty safely after too-cold weather.
If your "experimental row" does well, you can harvest it 1-2 weeks before the main rows. Be sure to pay attention to the flavor and tenderness of the experimental row: you might find that some crop is much better when grown on the cold edge of what it tolerates. or you might find that it can SURVIVE coldish wetaher, but never fully recovers and grows rapidly.
Every variety is somewhat different in the temperatures it prefers, and trial-and-error, in your own soil and micro-climate, are the only GOOD answers. Everything else is "what works for Joe Shmoe in his climate"
But "cool weather crops" can often take more cold than you might guess. I don't push them to survive actual frost, but that's because I don't have a lot of frosty weather and can afford to play safe. But there's a reason that many seed packets will advise you to sow that variety of that crop 2-3 weeks BEFORE the last frost. They know that those seeds will germinate on warm days, grow in warm and cool days, and just hunker down and survive very cold days. But they know that excessive summer heat will stomp on THAT variety like Godzilla on Bambi.
If your season for "cool weather crops" is short - like summer comes on hot and fast - then by all means plant some or all of your "cool weather crops" while there is still some risk of frost. those that can, will thrive on it. those that are slowed down, will suffer a little if you have a late spring. If you have an unseasonal late cold snap ... oh well, you may have to throw blankets over hoops to protect them, or have to re-sow a few things. But if hot summer is a'coming in, you might HAVE TO plant spring crops on the early edge ...
I just don't know central TN.
And
here's the real bummer if you're looking for "THE" right date to sow.
Every "garden calendar" and even the "average last frost date" are only
averages over a 20-30 year baseline. What frosts and chills will happen in the next few weeks is as unknown as next week's lottery numbers. The "average last frost date" means that
50% of the last 20-30 Marches had frosts AFTER that date. And in 50% of the last 20-30 Marches, you could have planted before the last frost date.
So every spring is a gamble. You can hedge your bets, push your luck, or pick some dates through experience and then play safe.
Do you feel lucky?
How eager are you to be the first on your block to have fresh tomatoes?
Would losing a few rows to a late frost break your heart or be a welcome challenge?
If you have time, energy, seeds and inclination, sow more than a month early and hope you get lucky!
There's no one BEST answer, and to the extent that there can be, only your experience in your garden will get you closer than 2-4 weeks.
Hope this is somewhat helpful. It sounds like you're already within a few weeks of knowing "the right dates". I'm trying to say that narrowing it down much more than that for each variety of each crop is a matter of personal preference, judgement and luck-of-the-weather.
But when you find some gardening neighbors (hopefully here or in the TN forum), a good first guess is "whatever they do". Then try some seeds 2-3 weeks earlier, and later, to see what YOUR ideal dates are.
P.S.
>> if you have a seed packet that says "very cold-tolerant",
Beware even that. First, they usually mean "very cold-tolerant for THAT species". Thus a tomato that is called "very cold-tolerant" is only cold-tolerant FOR TOMATOES. A relatively-warmth-loving broccoli will still be MUCH more cold tolerant than that tomato because all tomatoes need more warmth than any Brassicas.
Second, they are printing that seed packet for average climates. A seed packet that says "good summer lettuce" might mean "this does OK in summers in
mild climates, but if you live in Texas, WHAT, are you CRAZY???"
You've probably noticed that seed companies like Parks print "easiest to grow" and "favorite variety" and "best-tasting" on almost every variety!
to ATP
But my little 13000sf lot is flat as a fritter. Could I do the back yard over again I would build in a rock slope covered in dirt that would allow for a cave of sorts to use as a root cellar. 
