Last year I planted almost everything waaaaaaaayy too early (March 7th). Especially the tomatoes. The Sungolds were flowering about 3 weeks before I could put them out! Yikes!
The average last frost date is a bit contentious for the DC area. NOAA tells me it's around April 15th. Avid gardeners with far more experience than myself tell me not to place a tomato start outside until around May 15th because of random frosts. Who to believe? Last year I only planted warm season crops around the spring time so I used the 5/15 date and had good results.
I've decided, however, this year to split the difference: use the 4/15 date as the last frost date for cool season crops (lettuces radishes, beans, kale, etc) & use 5/01 as the frost date for warm season crops (this allows tomatoes, peppers, eggplants, etc be put outside on 5/15). I'm going to enter these 2 dates into Skippy's Garden Spring Planting Calendar (also, check out the blog. It's full of good info!) and use the output to determine my planting times. And we'll see how it goes from there...
So, here's my 2010 Planting Plan:
-2/11 sow indoors kale, mustard greens/collards
-3/2 (or when the soil is thawed) sow outdoors arugula and radish
-3/11 transplant kale, mustard greens/collards outside, sow indoors eggplant
-3/6 sow indoors peppers, marigolds, parsley & basil
-3/20 sow indoors tomatoes and swiss chard
-4/8 sow 2nd arugula, radish and swiss chard outside
-4/13 sow indoors cucumber and summer squash
-5/1 sow outdoors nasturtiums and carrots.
-5/15 transplant tomatoes, peppers, eggplant, summer squash, swiss chard and cucumbers outside
Now to go add these as appointments in my Thunderbird calendar (with 1 week reminders!).