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Roger Doiron
How do I know the optimal time for starting seeds in my area?


I came across this helpful little seed starting guide on the website of Johnny's Selected Seeds. It's pretty cool: you plug in your last frost date and the table automactically calculates the optimal time for starting seeds and setting out seedlings for your hardiness zone. If you're not sure when your average last frost date is, this webpage will help you find out if you're based in the US. Give the guide a whirl and let me know what you think: seedstarting2.xls Download Photo credit: dyogi

Question details

Hi, I first find the last spring frost date & the first fall date. Then I get my copy of"Square Foot Gardening". I turn to the correct crop. He also tells the last day to plant seeds before frost to bare fruit. Or call your county agent.
Planting dates are usually determined by the soil temperature, rather than the date. The best idea i read about for determining the correct soil temperature is to drop your pants and snuggle your bottom down into the soil. You will soon know if the time is right! I must say that i have not tried this technique myself yet.
I'm shy , so I will use my soil thermometer, then you will need a optimun soil temperature for germination chart like the one on page 210 of "Getting the Most from Your Garden" by Organic Gardening Magazine. I also got a "Home Vegetable Gardening" from the extension agent, which will know more about your zone/county/site. The temperature of some seeds for germination is 50f/10c, others 60f/15c, others70-80f/23-29c to germination. I know I depend on book way more then most. But that what we old timers did, before the garden site on the web were around. Most the gardener I know plant on Good Friday, but that works better in the Southern USA. Other parts of the Globe are out of my limited range of knowledge.
This year has been a real guessing-game. We had temperature swings of 25 to 45 degrees (from the 50s to the 90s, then back again) all winter and spring, and our hottest summer days were cooler than some spring heat waves. In a 'normal' year, you can work off your last frost dates. These are available from remote weather stations - you just pick the nearest on to you to get your frost dates. We live in a Mediterranian climate and can start many crops over a wide range of dates. I may plant beets 4 or 5 times a year, and I do multiple succession plantings on many veggies. The only real way to stay on top of this is to build a complete plan, back up from your planting date be the germination and grow-out dates, then do this for each plant. I actually use some pretty cool on-line garden design software to plan out my gardens. It is called GroVeg and gets its frost-date info from the weather stations for you - you just pick the station to use. GroVeg contains an easy-to-use drawing program to lay out your gardens, and drag-n-drop veggies. You can draw the veggies in rows, or expand the width of a row to plant on a grid. The program keeps track of each veggie and shows the date range for seed starting, planting out and harvest. You can break parts of beds out to go in on specific dates and this creates new entries on the planting calendar. You even get newsletters reminding you of upcoming garden tasks you have scheduled! All this information is collected, arranged and reflected on a planting calendar the program prints showing the plants, number you'll need, plus their starting, planting and harvest dates. There is a free trial period you can use to create your garden plan to see how you like the program.



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