Friday, February 11, 2022

Those seed starting questions, again!

Seed blocks starting onion seedlings

It's spring, or at least the cross-quarter tide that I call Spring Finding; you probably know it as Groundhog day. This is when I traditionally make my first soil blocks and seed onions to start on my grow rack. And, browsing the Internet, I am once again seeing the beginning of the seasonal “when do I start...” queries. Some are from new gardeners, others from those who were less successful than they would like to be and hope that learning more and perhaps changing the timing will help.

And just to clarify, I will be talking about growing food for your family to eat. I love flowers a lot, but my focus is growing food. Much of what I say and do will also apply to the plants that are "just for pretty.” If that is your jam, use the resources I mention and dig into learning more about your favorite flowers wants and needs.

Unfortunately for the new gardeners, much advise is offered from folks who simply repeat what they have always been told; traditional things that may or may not work in our Maine climate. I will be specifically focused on Maine, but many of these same resources can be personalized to other locations.

One of the most commonly asked questions, which is also one of the most commonly answered with misleading information, is "when do I plant..." Whether direct seeding into the garden, or attempting to grow ones own transplants in the house, timing does matter.

Transplants need to be started early enough to get a good start, and to get “hardened off,” before being transplanted, but not too early, or they may suffer from leggyness (getting too tall/being too weak.) They need sufficient light, water and nutrients -- but not too much. The proverbial sunny window sill probably won't work well alone. Here in the northlands they will need supplemental light. And as they grow larger, they need to be watched closely, watered often, and provided with a breeze or substitute to “fight against” to help strengthen their stems. But exactly WHEN to put those seeds into the potting medium, peat pots or pellets depends on what you are starting, and your optimal planting out date. That date depends on basically two things: your average last frost date and the frost-tolerance of the seedling.

About that last spring frost date – It is an average. Think back to school math days and remember how averages work, to decide how much you want to gamble and to what lengths you will go to protect the seedlings should the frost be on the late side or you decide to “push the season.” Then visit and find your location. Not in Maine? Replace maine in the URL with your state name!

Last frost zone map

A digression about the term ZONE is in order here. This simple word can be quite confusing. In the most common usage, it refers to “hardiness zones” which are a measure of average annual minimum winter temperature. Since the hardiness of a plant is largely measured by how well it can withstand cold winter temperatures, you can see this measurement relates to perennial plants – those that need to live through the winter. This data is not relevant to annual plants, which include most of the things in our food gardens (strawberries and some herbs to the contrary.) There is a 5 degree difference in the average winter low temperature between adjacent hardiness zones and Maine ranges from 3b in The County and mountains through 6a in a few locations on the southern coast.

The frost date maps, for average last spring and first autumn frost, also use the term zone. And coincidentally, there are also 6 spring frost date zones in Maine. Each of the zones spans 10 days and range from frost zone 13 (May 11-20) inland and along the central coast to frost zone 18 (July 1-10) in two areas in the crown of Maine.

Unfortunately, doing a search for “gardening zones” inundates the search feed with references to hardiness zones with no mention of anything relevant to annual crops, which are the most often planted. So no wonder folks are confused!

While my digression, above seems to indicate that the hardiness zones are irrelevant for annual planting, there is some small relevance. These commonly referenced zones also roughly correspond with general climate conditions, day lengths and growing seasons. So, for example, if a seed pack says the plant works for zones in the 7-8 range, chances are it is expecting a much hotter and longer growing season than we get here in the northlands. If you want to try it, be prepared to give it special care, to cater to its needs. There are other, very accurate ways to assess species and variety suitability for our climate. I'll get to that in a bit.

Interactive starting date calculator
Now that you know your average last frost, it's time to make friends with Johnny's Selected Seeds Growers Library. This helpful section on one of my favorite local seed suppliers' web sites is a gold mine of information, Click on the Planning Tools and Calculators link and then scroll down to the section “PLANT”. The first link will help you to learn when to start seeds indoors, transplant those seedlings and seed outside (assuming the soil is ready). Type your average last frost date into the box near the top of the Seed Starting Date Calendar and click ENTER and the spreadsheet will update the timing, below! One click and you have your planting schedule at hand.

You should also check for your average first autumn frost. will give you that data and once again, replacing maine with your state name will give you data if you need other locations. If you are like me and do not have a calendar in front or you, or do not want to count, will tell you the number of days between any two dates. Use it to get a rough idea of your growing season!

Gardening is far from an exact science that you can run by the numbers, though. The “days to harvest” that is commonly noted on seed packs and in those wonderful winter dream books we call seed catalogs does not start the clock until the seeds and germinated at the least; crops that are most

Weeding peas, an early crop
commonly grown from transplants, like tomatoes and peppers, start the count down when they are transplanted! Fact checking this with Google, I first read “The most widely accepted answer is to start the count the day you plant it in the ground.” but the entire first screen of actual entries from garden blogs and other resources had no consensus. One thing I will say is that counting from the day of germination or transplant equals “erring” if this is not correct, on the side of caution, and that is my choice when deciding if a particular variety or plant will give me a crop! And this same assumption will come much closer to giving you a constant harvest of crops that have short enough lives for you to plant more than once during the year.

These resources, when worked with your family's needs and likes in mind, will give you a good start on your garden planning, seedling starting and thinking about the days to come when we will be able to directly seed early crops, like lettuce, spinach and peas into the garden. While it appears that my “brain dump” of ideas is complete for now, I welcome questions about anything I have written here, and any other garden questions as we move forward into our gardening year in the next months. If there is anything else you would like to have me write about, please let me know. Contact is starwalkr (at) (not a link and written funny to avoid spammers).