Starting seeds indoors in winter is the inexpensive way to grow more of your favorite plants. Here's what you need to know to make your seeds blossom.

Updated April 30, 2018

Face it, people: Gardening can be pricey. New plants, tools, and all those extras can add up. So how do you slice your gardening budget? Consider indoor seed starting as part of the answer.

Many people are convinced that indoor seed starting requires both time and energy. They're wrong: You can start a few seeds or a lot. You can even fake it with what you have on hand—no need to buy anything special. Plus, with a bare minimum of effort, you can save vegetable seeds, flowers seeds, and herb seeds you're already growing, then use them during the next gardening season. Follow these tips on how to start seeds and which seeds can be started indoors.

Tips for saving your seeds.

Which Seeds to Start Indoors

If it's your first time starting seeds indoors in winter, go small. Pick just one or two types. Some good flowers to start from seed include these all-time favorites:

  • Marigolds: Sure, your grandma and your mom probably planted them. But there are loads of varieties to try, and marigolds rock from seeds.
  • Cosmos: Cheery cosmos often get mistaken for daisies but come in more delicate pastel shades.
  • Morning glories: Scatter these climbers along a fence for a sunny summer profusion of blooms.
  • Nasturtiums: Grow them, eat them: This edible grows vigorously and comes in loads of colors.
  • Sunflowers: Who doesn't love sunflowers? Bonus: Birds and bees are drawn to them, too.

See more edible flower varieties that are almost too pretty to eat.

Editor's Tip: Look on the seed package label to find the number of weeks you're supposed to start seeds indoors before the average last frost date. Count backward from that frost date: It's about six to eight weeks. That's when you should start those seeds indoors.

 Find the average last frost date for your area.

Starting Seedlings Indoors

To start seeds, you'll need:

  • Seed-starting pots with drainage holes
  • Seed-starting mix
  • Labels for each pot

Fill up the pots

Fill the pots with seed-starting mix, then moisten. The mix should be damp but not soggy—a spray bottle helps. You also can get the mix wet before adding it to the containers.

Press them down

Gently press seedlings into each container. If the seed package label advises it, cover the seeds lightly—but don't pat down the seed-starting mix.

Label and cover

Label your pots so you know what's growing. Loosely cover the pots with clear plastic wrap, which helps maintain humidity and warmth.

Grow pots in warmth

Place your seed pots in a location that's warm and free of drafts, but not in direct sun. The ideal temp is about 75 degrees F but not hotter than 90 degrees F. Once the tiny seedlings emerge, then about 70 degrees F is OK. Sunlight is a big deal, too—about 12 hours a day. To supplement natural daylight, place the pots up close to a low-intensity light—like under cabinet lights in a kitchen.

Starting Seeds Outside

Some germinating vegetable seeds are quick enough growers that the seeds can be planted right in the ground, after the outside temps and soil have sufficiently warmed up. To plant them, just check the directions on the seed package label. Cover with as much soil as directed, then lightly water. Some seeds, like marigolds and zinnias, you can simply scatter.

Growing Seedlings Indoors

You started your seeds. Their heads are poking up in the pots. What do you do next?

Give them some air

After plants pop through, take off the plastic wrap. Let them breathe a little bit.

Thin the seedlings

As the seedlings make their presence known, they need their space. Keep the ones that look healthy and strong, and snip the rest so there's just a single plant per pot.

Moving day

After they're about 2 inches tall, your seedlings need an upgrade. Transplant them into larger containers—this time in a potting soil mix.

Keep watch

Don't let the seedlings dry out! You can chill a bit under the indoor seed-starting lights as the plants get stronger, too. Fertilize lightly with a diluted seedling mix.

Harden off

As your plant-outside date approaches, you have a couple of days to boost the hardiness of your seedlings. To do that, you harden off the plants. What's that, you ask? Simply place the seedlings outside—in a protected spot—for a short time (think an hour or two). Every day, increase the length of time you leave them outside.

Container Options

Use seed flats—they're super easy for planting. But dig through your recycling bin, too. Just remember to punch a drainage hole in each container before planting. You can repurpose cut-down milk jugs, cardboard egg cartons, yogurt cups, and disposable pans.

Indoor Seed Starting Problems

Even if you do everything right, your sprouting seeds might struggle. Here's why:


Sudden wilt on seedlings might be a sign of damping off caused by a fungus that sometimes appears because of overwatering or overcrowding. Solution: Poke holes in your seedling container to better air circulation. Visible fungus can be scraped away with a spoon.

Floppy, leggy plants

Not enough sun or too-hot temps can result in leggy seedlings. Solution: Water your seedlings more consistently and rotate them daily so all sides get equal sun exposure.

Curling or discolored leaves

Fertilizing seedlings indoors too much makes for uneven, struggling seedlings. Solution: Flush the seedlings with water and repeat every few days to rid them of excess fertilizer.


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