The most common seed starting question I receive from readers is some variation of When should I start my seeds?  Especially for those of us here on the frozen tundra of Minnesota, we tend to feel like we’re falling behind when our gardening friends in warmer zones are preparing for planting next month while we are still crossing our fingers that Monday was the last of the sub-zero temperature for the season and please, oh please, don’t let it snow in May again this year!

This of course, gets right to the heart of the mater: spring is so predictably unpredictable, that it’s completely understandable why gardeners sometimes struggle with when to start seeds.  The optimist in me wants to start everything right away, because there’s always a chance that I might be able to get in the garden ahead of schedule (and also, who doesn’t like having cute little green seedlings to look at instead of the snow outside the window?), but the realist in me thinks about how deep the frost line must be after week after week of sub-zero weather since the beginning of December.

So let’s lay it all out and make some sense of it, shall we?  The first thing you need to know is your average last frost date.  This date is going to be your base for determining when you should start your seeds to ensure that they are, first and foremost, mature enough to plant out and produce within the growing season, but also not too overgrown or leggy that transplanting is stressful or difficult.  Once you know your date, you simply have to count backwards, based on what you intend to start from seed:

seed starting timeline

14+ Weeks to Go: 
Use this time to get your garden in order: finalize your garden plan, purchase seed, and round up the rest of your supplies.  Mark your start dates on the calendar to hold yourself to sticking it out until the actual date.  A few days before you start your seeds, prepare your seed starting containers and get them on a heat mat or other warm place to warm up the soil.

12-14 Weeks to Go: 
Get the slowpoke artichoke seeds going along with the alliums (onions and leeks) and umbellifers (celery and also a number of herbs).  These plants definitely need the extra weeks to reach maturity, so if you haven’t already planted them, start them NOW!

10-12 Weeks to Go: 
Remember this group as the (mostly) green and leafy group.  Start your brassicas: cabbage, kale, broccoli, brussels sprouts, and cauliflower.  If you would like to grow head lettuce, this is a good time to get that going, too.

8-10 Weeks to Go: 
Unlike the other plant families, the solanaceae family is spread out over a slightly larger window of opportunity.   Peppers and eggplant germinate and grow at a slower pace, so give them a little head start.

6-8 Weeks to Go: 
Tomatoes and tomatillos are much faster growers than the other members of the solanaceae family, so it’s usually a good idea to wait just a little longer before starting those seeds, especially if spring can be a little unpredictable where you garden.

4 Weeks to Go: 
Cucurbits can go either way: you can sow them indoors or direct sow them into the garden. Starting indoors gives them a little bit of a head start, which is nice if your garden season is short, and it can also be an effective means of out-squirreling the squirrels and other critters that find freshly planted pumpkin seeds irresistible.  It’s important not to start these plants too early, as they can be difficult to transplant if they get too big.

2-4 Weeks to Go: 
As the weather allows, start to harden off your seedlings by setting them outside for increasingly longer periods of time.  Gradually introduce them to sunlight, wind, and even rain, if temperatures are warm enough.  Once your seedlings have been properly hardened off and the threat of frost has passed, you’ll be ready to transplant them into the garden!

Keep in Mind: 
Of course, there are few rules that are set in stone when it comes to gardening, and there are always some exceptions and variability from garden to garden.  There is wiggle room in this timeline.  If you move a week  in one direction or the other because life got too busy, or you just couldn’t wait any longer, your garden isn’t likely to suffer.  After all,  your last frost date is an average date and not a guaranteed date, so it’s already a moving target!  You might be able to put your seedlings out two weeks early, or you might have to wait two more weeks after that date has come and gone.  If you stick close to the ranges above, you’ll be fine either way.

Happy seed starting!


Timing is Everything: A Seed Starting Timeline
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