How to Read a Seed Packet: What You Need to Know

by Fern on January 10, 2010

in Fruits & Vegetables,Herbs,How To

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Growing things from seed is incredibly rewarding and fascinating, not to mention fun. But there are a few things you need to know before you get started. And if you buy good quality seeds, you’ll find everything you need to know on the seed packet itself. But you still need to understand what the info on the packet means, and how to use it to your advantage.

I am using a seed packet from Botanical Interests, because their packets are unbelievably jam packed with information.

First, and foremost, every seed packet should list the common and Latin name of the seed inside the envelope. Surprisingly, some seed producers do not list the Latin name. Since it is not uncommon for two or three (or even more) plants to have the same common name, the Latin name can help you figure out whether the seed packet you’re holding has the seeds you want or not.

Once you’ve confirmed that the seed packet you’ve found does in fact have the seeds you want, check for a date on the packet that lets you know whether the seeds are fresh or not. Some seeds last for a long time, while others are only viable for a year or two after being harvested. It’s probably safe to assume that if a seed packet says “sell by 12/10″ that the seeds are still viable for several months after the “sell by” date. If you’ve found a packet in your stash that says “Packed for 2008, sell by 12/08″ and it’s January of 2010 you might find that the seeds in the packet won’t germinate, or only a few will germinate. If you’re dead set on sowing old seeds, sow lots more than you normally would and be prepared for mixed results.

When looking at the back of the seed packet, look for information about whether the seed should be started inside, or should be directly sown outside. And look for information about when to sow it. Plants that aren’t suitable for starting indoors usually either need cold temperatures to germinate, or don’t like the disruption of being transplanted.

Seed packets often refer to “last frost” and “first frost.” Last frost is the average date on which a particular area no longer experiences any freezing temperatures in the spring. First frost is the average date on which a particular area experiences their first freezing temperature in the fall or winter. So the growing season in your area is roughly between the last and first frost dates. This is a good resource for determining your city’s frost dates.

To determine when to sow your seeds, simply count backwards from your area’s last frost date. If you want to really geek out and determine the right day to sow your seeds based on soil temperature, you’ll either need a soil thermometer, or you can consult a soil temperature forecast. I’ve never done either, but then I live in Southern California and we have a lot more room for error here.

It’s a good idea to write down (or use an online gardening journal) the dates on which you sow seeds. You think you will be able to remember, but trust me, you won’t. You’ll need the sown on date to use the information pictured above. “Days to Emerge” refers to how long it will take before you see leaves poking up through the soil. You should keep the soil evenly moist but not soggy while waiting for the plant to emerge. If, in this seed’s case, you haven’t seen any signs of life 10 days after sowing, something has gone wrong, and it’s time to start over. The soil may have dried out, it may have been too soggy, or a critter of some sort may have eaten your seed.

The rest of the information below “Days to Emerge” tells you how to sow the seed. In this seed’s case, You should make a hole approximately 1/2 an inch deep, place the seed in the hole, and then cover with soil. Repeat this process approximately 1 inch down the row, all the way to the end of the row.

The packet then instructs you to thin the plants when they are 1 inch tall. This means that you should pull out extra plants so that the remaining plants are 4 to 5 inches apart. Try to pull out the seedlings that don’t look healthy and leave the ones that look the strongest. But you will have to pull out healthy looking seedlings. It’s just the way it is.

Now you just have to keep on watering and fertilizing (if needed, as directed) until the plant is ready to harvest (if it is an edible plant). The seed packet should give you a hint of when you’ll be able to harvest. In this case, it is between 27 and 40 days after the seedling emerges. At least, I am assuming that’s what this day range means. Usually when a packet says something like “90 days” thats the amount of time after the seedling was ready to be transplanted outdoors. But in the case of this spinach, it is supposed to be directly sown, so I am guessing that rule doesn’t apply.


Have questions about starting plants from seed? Ask in the comments section and I’ll do my best to answer (or help you find the info you’re looking for).

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{ 9 comments… read them below or add one }

Gigi @plangardengal in Twitter January 10, 2010 at 12:38 pm

Helpful article, esp. on seed expiration dates. I sometimes get paranoid with “old” seeds but have actually had success with many seeds even 3 yrs after the packing date, making sure I double or even quadruple the amount sown. It definitely depends on what kind of plant seed you’re sowing.

BTW you can also use the nearest *weather station* to your town to find out frost dates – really important for areas with significant microclimates due to e.g. mountain and lake effects. Here’s a FREE service to get your weather station: http://www.plangarden.com/share/ Type in your ZIP code (or town, country as we have weather stations for Canada and UK), click on “Search” button, then “Get Weather Stations”, and then select the closest weather station by clicking on the one nearest to your home. Just remember that Mother Nature is fickle, so neither frost date, soil temp or Zone is a foolproof way to guarantee successful germination!


Fern January 10, 2010 at 9:05 pm

Thanks for sharing that tip about weather stations Gigi!

Kat January 11, 2010 at 9:34 am

Very helpful article. I love the link on the city’s frosts dates. So helpful.


Evangeline January 11, 2010 at 4:55 pm

Thanks for this great post! I just bought a bunch of seeds yesterday and am ready to plant. Very exciiting. I went to a class on Saturday and was told it’s okay to just use regular potting soil. However, Sunset WG says to use a “planting mix”. What’s your opinion?


Fern January 11, 2010 at 11:22 pm

Evangeline–I’m not sure what Sunset WG is referring to by “planting mix.” Any good general purpose potting soil will do the trick. There are specialized potting soils especially for “fruits & vegetables” or “flowers,” etc, but you don’t have to use one specifically for what you intend to grow. Those soils just come pre-mixed with fertilizers and soil additives formulated for a specific kind of plant. You just want to make sure it says somewhere on the bag that the soil is for containers. Other types of soil meant for an in-ground garden are heavier or too dense, or otherwise unsuitable for containers.

Sincalir January 20, 2010 at 11:52 am

Great post! I am writing about hardiness and zones today and how to find the hardiness zones on seed packets. I linked your article in my post as a general tutorial on reading seed packets. I love that you chose Botanical Interests packets because I use these seeds heavily. I always use only Heirloom varieties.


brigitte wurn christensen March 3, 2011 at 7:48 am

For starting seeds I have found the Jiffy seed starter mix works great and its really inexpensive. It is a super lite sand like mixture that is sterile, which is really important. Also it is really easy to save seed. I have a friend who thinks tomato seeds are too expensive so she buys a fresh tomato, the best one she can find, then she scoops out the seeds, puts them in water (for tomatos only) lets them ferment, in a week or so she drains them onto a paper plate, lets them dry and puts them in a little jar until she is ready to plant. Free seeds if you even take them from a salad at a restaurant. Just a thought


Fern March 3, 2011 at 6:36 pm

Brigitte–Most of the tomatoes that you buy at the market are hybrids, so the plants that grow from their seeds will not be exactly like the tomato purchased at the store or restaurant. Which is ok, sometimes those plants produce great fruit, but it will be a disappointment if you were hoping for exactly the same tomato.

brigitte wurn christensen March 9, 2011 at 8:17 pm

Hi Fern, Yes I see how that could happen. I am going to try the new grafted tomato’s this year, I will you know what happens.
Thanks Fern for the great advice


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