How long is my growing season?

This was the first year I started growing annuals and I’m a bit confused on growing season length. When I purchase seeds online it seems 60-70 day crops are short season for northeners whereas longer crops seem to be 100+ days. I’m in the Chicago land area and when I google growing season it varies from 150-200 days. How can this be? Chicago is a very cold area (zone 5). Any help on this would be appreciated.


First define growing season "the part of the year during which rainfall and temperature allow plants to grow.

“a short growing season”"

Lettuce, spinach, turnips and others can tolerate very cold weather. One thing lacking from the definition is sunlight. Sunlight is less during winter months which plants need to “grow”. Growing season is when plants like turnips can grow which is more about the number of sunlight hours and less about temperature and rainfall than a person might think. If it does not rain or the temperature is not warm we could water and still grow lettuce as long as there is enough light. In Kansas our growing season starts in March and ends in October or November for many crops. Winter wheat is planted in any month ending in r so September, October, or November, or December. Winter wheat grows all winter ripening July of the following year. Rye has a similar growth habit. Technically we can grow things all year. The question is does anything really grow or does it just stay alive when it’s -20 F? That’s where the sunlight comes in its required.

" your frost-free growing season starts Apr 20 and ends Oct 24 , totalling 187 days."


@clarkinks has covered it pretty thoroughly. However, I’d like to note that it’s more than just the zone and length of frost free weather. You and I are both in Z5, but your first frost is later and last frost is earlier. Also, your summers get hotter than mine. So you’ll probably have an easier time of things like eggplant, okra, and cowpeas than I do.


For the Chicago area you are looking at a growing season of about 172 days. This is an average value and it will vary from year to year in practice. In dense urban areas like the city proper it may be a bit longer due to the “heat island effect” that large cities have.

Take a look at this link for a web page that has a map of Illinois showing the length of the growing season. It also has lots of good info about frost dates, freeze dates and state maps for freezes and frosts.


When you first start gardening, you will try many things that fail, but if you keep good notes on when you plant each type of vegetable plant or seed, then you will gain an invaluable reference for future years. The book “Joy of Gardening” by Dick Raymond is an excellent read for new gardeners
Kent, wa

1 Like

Zones are a good starting point but there is so much more to growing fruits and veggies than zones. Zones only tell you the average lowest temperature. I think zone 5 is supposed to get down to -20 and we have not gone over -10 in years here where I live so I even question growing zones at this point. I think we may be a zone 6 at this point in time and Master Gardeners on Youtube that live in my area have said the same thing. Then we are talking about growing season like you. Growing season does not take into the account of massive sunrays and extreme heat that may ripen stuff faster. Then we get into disease and pest resistance. Fireblight is a major issue in my area with apples and pears trees so I will want to buy a resistant rootstock to that for example. Then we get into soil ph where things are hardy to my zone but will not live here where I live because they require too low of PH like blueberries for example. Google says that your growing season is 187 days by the way.