A Handy Seed Date Calculator

Not sure when to sow the seeds of vegetables, herbs and common flowers? Johnny’s Selected Seeds has a handy-dandy on-line seed-starting date calendar. 

It couldn’t be simpler. Add the spring frost-free date* (mm/dd/yyyy) for your locality and click Enter. The table will then give you an appropriate date for sowing indoors as well as an approximate date when you can expect to be able to transplant the plant in question into your garden.

Try it and see: it’s really quite accurate and will help prevent you from making that oh-so-common error of sowing your seeds indoors too early.

For example, my frost-free date is June 10 (the average last frost for my municipality is May 17, 3 weeks earlier), so I entered 06/10/2020. After I clicked Enter, the tables shows I should sow basil on the 6th of May and plant it out around June 21st while I should start broccoli from April 15 to 29 and expect to plant it out May 27. Pretty cool!

*The spring frost-free date is not the average last frost date given on many weather and almanach sites. The latter date only indicates that, one year out of two (i.e. the average) there’ll be no frost beyond that date. You want the frost-free date, probably about 1 to 3 weeks later, when the risk of frost has dropped to nearly zero. For more information on the spring frost-free date, read The Real Spring Frost-Free Date for Your Seeds.

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

1 comment on “A Handy Seed Date Calculator

  1. These are helpful, because all the older people who used to tell me when to plant are no longer here. No one knows this stuff like they used to.

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