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I have quite a few new gardeners ask me, “When should I start seeds?” It really depends on where you are and what you are planning to grow.

Most seed companies label the packets with basic growing information, but seed starting charts can help keep your gardening a little more organized.

A planting schedule can help you to spread your planting out so you don't feel rushed. When you try to cram too much to do in too little time, it doesn't get done properly. Vegetable gardening should help relieve stress, not cause it.

In this article, I'll share when to start seeds indoors and outdoors, with charts for fall and spring. We also cover tips for happier transplants and grouping your seedlings into crop families.

Seed Starting Tips

If you need tips on how to start seeds, please see, “Starting Seeds Indoors – Step by Step Guide with Troubleshooting Tips“.

We cover how to choose the right seed starting mix or potting mix, when to use a heat mat, proper air circulation, drainage and grow lights.

Remember, a rule of thumb is that seeds get planted roughly 3 times as deep as the diameter of the seed. Don't bury tiny seeds, or they'll have a tough time reaching the surface.

Using Plant Families to Plan When to Start Seeds

If you're anything like me, you have dozens of little seed packets waiting for you to give them some love and some quality dirt time. I like to sort my seeds into crop families, because when you grow plants that are similar, they have similar care needs.

The Crop Families I use are:

Herbs – Start Indoors and Direct Sow

Flowers – Start Indoors and Direct Sow

Tomatoes – Paste, slicing and small-fruited

Other Nightshades – Peppers, Eggplant, Tomatillos, Ground Cherries, Cape Gooseberries, Huckleberries

Leafy greens – Spinach, strawberry spinach, mache, lettuces

Brassicas – cabbage, broccoli, kale, Brussels sprouts, cauliflower

Cucumbers – pickling, slicing, and Armenian

Melons – Muskmelon, Watermelon, Honeydew and other heirloom melons

Root vegetables – Carrots, turnips, beets, parsnips, rutabagas, kohlrabi, radishes

Onions

Beans – Snap and Shell

Peas – Snap, Shell and Snow

Corn

Potatoes

I mix flowers and herbs in with my fruit and veggies as companion plants. For more information, see Companion Planting in the Garden.

Stratification (Cold Time Before Planting)

Some herb and flower seeds require stratification (time in the freezer) for germination. Check your seed packages or garden catalog for this information when trying new varieties.

Also, if you want really early flower blooms, you have to do like the nurseries and start your plants very early. In some cases the decorative spikes for flower basket are started nearly a year in advance.

I don't like the extra hassle of starting seeds super early, so I don't sow seeds until around mid March – except for onions, which I sometimes start in February.

How to Use the Seed Starting Charts

To use the seed starting charts, you need to determine the average last date of spring frost and the average first date of fall frost in your area.

You can do this based on experience, by contacting your local cooperative extension office, or by checking online at a site like Dave's Garden Frost Date by Zip Code calculator.

Please note that these dates are somewhat like a serving suggestion – what you see may not always be what you get. Mother Nature has her own ideas about each given year.

I've been caught on several occasions scrambling to cover transplants when an extra late frost hits. See “Protecting Plants from Frost – 12 Ways to Beat the Cold Weather” for tips to deal with wonky weather.

When to Start Seeds Indoors and Transplant Seedlings Outside

You need to know your local growing season. Once you find your average frost free date, plug that date into the chart and use it to calculate when to plant vegetables.

If you plant the seeds too early you will likely lose your crop. Planting your seed to late and you may not get ripe vegetables. Timing is everything.

For example, my average date of last frost is May 26. I start seeds over the spring months based on that date.

Green Bay, Wisconsin Seed Starting Calendar

Adjust your planting schedule based on your average frost free date. For instance, if your last frost free date is May 15, you should seed early cabbage indoors in Late March, harden in Late April, and transplant in Early May.

What Does “Harden” Your Plants Mean?

In the chart, you'll see the word “harden”. When you start plants inside, they need a gentle adjustment period before moving out to the garden full time. This is referred to as “hardening off”.

You make your plants tougher (harden them) so they are able to withstand the wind and sun of being planted outdoors.

To harden off seedlings, I place them outside in a protected location on a nice day. Indirect sunlight out of strong winds is best to start. Make sure they are not in strong direct sunlight. Too make sun bakes little seedlings very quickly.

One the first day they go out for a few hours, then longer as they have a chance to get used to the change. Be mindful that small seedling containers may dry out much faster outside than indoors.

I usually move mine out to my cold frame, and then lift the lid to expose them to moving air. Once they are used to that exposure, I move one batch out of the cold frame and the next batch in.

We have a lot of wind, so I still tend to keep seedlings near our home or cold frame until transplanting out in the garden.

When transplanting into the garden, it's best to pick a slightly overcast with little wind, if possible. I plant later in the afternoon, so the small plants aren't exposed to the midday sun on their first day out.

For a more detailed explanation and photos of how I plant out my tomato transplants, visit “How to Grow Tomatoes Organically – 7 Steps for Success“.

Spring Schedule of Outdoor Seed Sowing

Start these seeds directly in the garden in spring, or start indoors and transplant at the times listed below.

* Best as transplants

Summer Schedule of Outdoor Seed Sowing

You can start seeds directly in the garden for the plants listed below to get an extra late season harvest. Keep in mind that you'll need to keep the soil moist and not too hot for germination. (Light mulch such as grass clippings can help.)

Consider planting your low growing fall crops inside a small cold frame, so that you can cover them to extend growing and harvest.

See ” Protecting Plants from Frost – 12 Ways to Beat the Cold Weather” for more ideas.

To get the printable version of the charts, click the link below. The pdf displays the calendars more nicely than they display on screen.

Adjust the dates for your area and keep them in your garden planner.

Click Here for Printable Seed Starting Calendar PDF (dates left open)

Free Garden Planning Excel File

If you'd like to get the charts in Microsoft Excel format that you can edit directly, you can sign up for our newsletter.

With your subscription, you'll get free access to the Common Sense Home Garden Planning Kit, which includes:

Seed purchase log

Planting and Germination record

Seed Starting and Transplanting Calendar

Customizable seed sowing schedule

Seed longevity chart

Seed germination rates after storage

Plant spacing chart

You'll also get regular updates throughout the year with gardening tips, and other practical information.

More Gardening Tips and Information

You may also enjoy our Gardening page, which lists all of our gardening articles, including:

Some handy seed starting supplies.

Some of my favorite garden helpers.

I was hunting through old photos for this post, and this was too cute not to share. Now they've grown into strapping young men. 🙂

Originally published in 2014, last updated in 2020