After speaking with many nurseries, gardeners, bloggers and local sites, the consensus for the last frost day here in Seattle is Mothers day weekend.
However if you want to be really sure of the last spring frost date in your area and you like the science, check out http://cdo.ncdc.noaa.gov - Climate Norm's very cool tool, just enter your State then location and it bases the date on local weather patterns. You can choose from a 90% chance of frost, a 50/50 chance of frost or play it real safe and opt for the 10% chance of frost.
- My 50/50 date would be: April 11th
- While my 10% date is: April 27th (which I would feel safer using)
- Mothers day this year is May 13th (I figure by this date it will be safe for me to start sowing or transplanting to the veggie beds! I'm so not a risk taker when it comes to sowing for the first time!)
So why is the last spring frost date so important? Basically most seeds prefer to be sown when the ground is warmer and the last chance of frost has passed as to not burn any new shoots or freeze and shock the seed (I can relate, who likes being in the garden when it's freezing anyway!)
But in saying this, I am surprised by how many cold season seeds thrive in these conditions, many of the green's like lettuce, broccoli and pea's love the colder weather and its been suggested to plant before the last frost as it can make for a tastier yield, they kinda like it...crazy seeds!
My Sow calendar for Spring 2012
March 12th - 18th - set up an area for indoor sowing!!
March 19th - 25th - Start sowing tomatoes indoors/coldframe (10-14days germination)
March 26th - April 1st - Indoor/coldframe sow onions* (21-30days germination)
April 2nd - April 8th - Indoor/coldframe sow broccoli (6-10days germination)
April 9th - April 15th - Indoor/coldframe sow lettuce (2-14days germination)
April 16th - April 22nd -
April 23rd - April 29th - Transplant Broccoli (thin12-18in apart)
April 30th - May 6th- Direct sow beans (6-8days germination, thin to 8in when plant has 4leaves)
May 7th - May 13th - LAST SPRING FROST -
May 14th - May 20th - Direct sow carrots (14-23days germination) Direct sow cukes (5seeds per mound)
May 21st - May 27th - Transplant lettuce (10-15in apart) Transplant onions
May 28th - June 3rd - Transplant Tomatoes (1.5-3ft apart) Thin carrots (1in apart) Thin beans (s.a)
June 4th - June 10th - Thin Cukes to best 3/mound
*onion thinning - 25mm(1")-50mm(2") apart and then again later to 10cm(4")
Like most things in the world of gardening, this is all subject to change and is a rough outline for what I should be doing during what week. It might help me stay on track better when I work the plan and not just guess as I go. I have had so much wonderful advice on what to start when and little tips that fellow bloggers have suggested. Check out the awesome comments here on my I have my veggie seeds...now what? post! Thank you for all your wonderful advice!!!