When and How to Start Seeds Indoors

Tools for starting seeds inside

Starting seeds indoors is a great way to get a jump on spring gardening.

Need to beat cabin fever while snow still clings to the windowsills and frost hangs heavy in the air? There’s no better way to do it than coaxing a pack of seeds into germinating indoors. Starting plants indoors may be one of the best things you can do for your garden. Not only does seed starting allow you to choose from a much wider range of plants, but you will also know that your mature plants are healthy since you raised them from wee little seedlings.

What Materials Do You Need to Start Seeds Indoors?

Veteran gardeners know the secrets of starting seeds indoors, but if you’re at the beginning of your gardening adventure, you probably have a lot of questions. Knowing how to start seeds indoors saves the sometimes considerable costs associated with using transplants for annual flower, herb or vegetable gardens year after year. With your shiny, new seed packets in hand, you should go about collecting the necessary supplies for seed starting.

Many gardeners use inexpensive, prefabricated tabletop greenhouse kits for starting their seeds. These units are available at home improvement stores and through garden catalogs. These miniature greenhouses provide casual gardeners with almost everything they need to start a few plants with very little experience. They generally come with compressed peat pellets with a dimple in the center to place your seed. As you water them, they expand impressively to form net-wrapped wads of growing medium, which are easy to transplant when the time comes.

Gardeners who start many seedlings year after year may find these units limiting, though. For a DIY option, you can make your own biodegradable pots from newspaper, fill them with a peat-based seed starting medium, and put them into large clear plastic sweater boxes. Some home gardeners use an egg carton and put the soil and seeds inside cracked eggshells. You can also simply sow the seeds directly in a window box liner or planter liner, which can easily be moved outside when the plants are ready. No matter what you choose to start your seedlings in, you’ll need to add artificial fluorescent lighting, but a CFL bulb in a lamp may be enough for a few seeds.

Egg carton and egg shells with young plants

Do-it-yourself seed starting in eggshells! Image from Hew and Sew.


How to Plant Seeds Indoors

Every seed needs to be handled a little differently. Your seed packets will explain how deep to plant the seeds and if any special treatment is required prior to planting. Small seeds are generally just sprinkled across the top of pre-moistened seed starting mix, but bigger seeds, like watermelons or pumpkins, may benefit from deeper planting. There are some oddball seeds out there, but for the most part the bigger the seed, the deeper it needs to go. Before you poke them into their individual cells or pots, check your seeds carefully to ensure they’re clean and free of any fuzzy surface molds that might cause them to fail.

Once you’ve given your seeds the all-clear, water them just enough to keep the growing medium from drying out, sit back and watch carefully for the new seedlings to emerge. Some seeds take longer than others to germinate, so be patient with your indoor seed starting. If they go more than about a week past their ideal germination window, though, it may be time to try again with fresh seeds. Sometimes seeds are just bad.

Black plastic window liners

Consider starting your seeds in window box liners. When they’re ready, just carry the liner outside to your flower boxes!


When Should You Start Indoor Seeds?

To get your planting time right, you’ll need to figure out the average last frost date for your region. Almanac.com has an overview of major U.S. cities, and Dave’s Garden lets you look it up by zip code. Determine when the danger of frost has passed and then count backwards to find the date for starting your seeds.

The chart below shows the germination and transplant times for some common garden flowers, herbs, and vegetables. Specific information can be found on your seed packets, too. Plan the timing carefully, because you don’t want to put out seedlings that are too young to survive, nor do you want to move leggy transplants out to the garden.

Starting seeds indoors can be incredibly rewarding, especially when your flowers, herbs or vegetables are destined for a durable, long lasting planter from Hooks & Lattice. As soon as those little plants pop their heads out from the soil, it’ll feel like spring has already sprung! Have you successfully started seeds indoors and transplanted them outside? Tell us about it in the comments!

Common Name Days to Germination Weeks to Transplant
Aster 8 to 10 days 7 to 8 weeks
Coleus 8 to 10 days 9 to 10 weeks
Dianthus 5 to 7 days 12 to 14 weeks
Impatiens 15 to 18 days 10 to 11 weeks
Marigold 5 to 7 days 12 to 14 weeks
Pansy 6 to 10 days 14 to 15 weeks
Snapdragon 7 to 12 days 15 to 16 weeks
Vinca 10 to 15 days 14 to 15 weeks
Zinnia 5 to 7 days 8 to 9 weeks
Basil 5 to 15 days 6 to 8 weeks
Chives 10 to 14 days 6 to 8 weeks
Cilantro 10 to 15 days 6 to 8 weeks
Dill 21 to 25 days 4 to 6 weeks
Lavender 15 to 20 days 6 to 8 weeks
Oregano 10 to 15 days 6 to 8 weeks
Parsley 15 to 30 days 8 weeks
Peppermint 15 to 30 days 6 to 8 weeks
Sage 10 to 21 days 6 to 8 weeks
Thyme 5 to 20 days 6 to 8 weeks
Fruits & Vegetables
Broccoli 5 to 10 days 6 to 8 weeks
Cucumber 7 days 3 to 5 weeks
Lettuce 5 to 10 days 6 to 8 weeks
Okra 7 to 14 days 4 to 6 weeks
Pepper 7 to 14 days 6 to 8 weeks
Pumpkin 7 days 4 to 6 weeks
Tomato 7 to 14 days 6 to 8 weeks
Watermelon 7 days 3 to 5 weeks
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