Understanding Sowing Dates on Seed Packs

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Always read over any seed packet before you sow! Ill.: ccognh.wordpress.com & www.clipart.email

So, you’ve bought a few packs of seeds: annuals, vegetables, herbs, etc. and you’re back home, excited to get started sowing them. Before doing so, though, read the information on the back of the pack. It has all sorts of important details: how deep to sow, how to space the seeds, etc. and, perhaps most importantly, when to sow the seeds it contains.

Seeds You Sow Outdoors

Sometimes it will indicate you should sow the seeds directly outdoors, where the plant is to grow. There will likely be a precision like:

• Sow as soon as the ground can be worked: That means sow outdoors early in the spring, after the ground has not only thawed out, but is no longer soaking wet.

• Sow when the soil warms up: Unless other details are given, assume this means when the soil reaches 65˚F/18˚C.

• Sow after all danger of frost is past

• Sow after final spring frost

• Sow after average last frost

• Sow after the danger of spring frost

• Sow after last frost

These terms all mean the same thing, but do not refer to the average last frost date that your local weather station might give you … or at least, should not. Remember that “average” means there’ll be a frost after that date about every second year. (That’s what average means!) What you need is the “frost-free date,” one at which there is little to no risk of frost, probably at least 2 weeks after the average last frost date. Ask your local garden center or garden club when they consider all risk of frost to be over for the season … but always be ready to adapt to any special weather conditions. An extra cold spring would mean delayed sowing for many seeds, for example.

Seeds You Sow Indoors

Alternately, the seed pack may indicate you should start the seeds indoors. Then, after they’ve sprouted and grown for a while, you would then transplant the resulting seedlings into the garden … usually “when all danger of frost is past” (see above) or “when the soil warms up” (see above). This gives slow-to-mature plants a head start on the season.

This packet suggests you can sow outdoors (“Direct Sow”) or indoors and gives an idea when to do so in both cases. Photo: Nan Schiller, gardenerspath.com

Explaining when to sow seeds indoors is usually done in the form of a statement like:

“Sow indoors xx weeks before last frost.” 

So, pull out a calendar. You need to find the frost-free date for your locality (see above), then count backwards the number of weeks mentioned to determine when to sow indoors. 

Simple, but…

Sometimes, a range is given, as follows: 

“Sow indoors xx to xx weeks before last frost.” 

This may seem like the seed supplier is giving you a bit of a choice, but there is actually a hidden meaning behind the use of two dates. 

If you sow your seeds inside your home where warm temperatures are the norm, the lesser of the two dates will give the best results (i.e. if the packet indicates 6 to 8 weeks, choose 6). 

If you sow in a greenhouse, where lower night temperatures are likely, choose the greater of the two dates. 


And there you go! All you have to do is remember to apply the information!

Organize Your Seed Packets According to Their Sowing Date

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Organize your seed packets according to the sowing date order so you remember just when to sow them. Source: Claire Tourigny, from the book Les idées du jardinier paresseux: Semis

If you sow only one variety of seed in a given year, setting up a sowing schedule is not that difficult. You only need to determine the best sowing date, which is probably indicated on the seed packet. For example, the packet may indicate “sow indoors 8 weeks before the transplant date.” You only have to count backwards according to this information. For example, if the date on which you plan to transplant is June 1st, you only have to remember that the contents of this packet should be sown about 8 weeks earlier, around April 1st. That’s not too hard to remember.

If ever this information is not given on the packet, you’ll find helpful lists of commonly grown plants with their best sowing date in the blogs When to Sow Over 80 Vegetables and Herbs and When to Sow Over 150 Annuals.

However, when you have many seed packets you intend to sow, things can get complicated. You’ll quickly learn that the needs of various seeds vary: if one variety prefers being sown 12 weeks before the last frost, another is best at 8 weeks, while yet another is best sown directly outdoors two weeks before the last frost … and the list of possibilities goes on and on.

How can you organize things to avoid any confusion?

Here’s a suggestion: Prepare envelopes (no need for new ones: you can recycle used ones) ahead of time, according to the dates you’ve calculated: March 1st, March 15th, April 1st, April 15th, etc. A personal diary or a small binder with pockets would also be effective. Now, as you buy seeds, simply place them in the appropriate envelope or pocket. That way, no confusion: you’ll always be ready to sow the right seeds on the right date!