A Gardener's Guide to Starting Seeds Indoors

You can sow (plant) the seeds of most fruit and vegetable plants directly into your garden. It's the most affordable, convenient path to a bounty of fresh, delicious produce from your own backyard. So why would anyone want to buy costly seedlings (starter plants) from a nursery or sow seeds indoors instead of outdoors?

Put simply, you cannot put every plant or seed directly into the soil because the growing period of some plants is longer than the growing season of your hardiness zone. Therefore, some plants need to be grown indoors (or at a nursery) before you can transplant them into the garden. Starting your own seeds indoors is more economical and will give you a head-start on the growing season. Plus, you'll be able to experiment with a wider variety of plant species than the common varieties of seedlings available at your local nursery.

You should always consult the back of your seed packets for exact planting instructions, but here are some examples of plants that typically need a head start indoors (including the number of weeks prior to your zone's last anticipated frost date that you should start the seeds indoors): Starting Your Seeds Indoors
There are 10 simple steps to follow to start or "germinate" your seeds indoors. If you buy seedlings from a nursery, skip to step 8 below.

1. Choose a location. The best place to germinate your seeds is an area away from the everyday traffic (and pets) that's also warm, full of light, and free from drafts. Basements, shelves, and sun porches usually make suitable locations.

2. Gather your trays. Seed starting mixtures and trays are also widely available at nurseries and home improvement stores, but you can also make your own trays out of egg cartons, yogurt tubs or other "recycled" containers. Whatever you use, it's a good idea to sterilize your trays, especially if you are reusing them, and to use trays with adequate drainage holes at the bottom.

3. Plant your seeds. Fill your trays or containers about 2/3 full with your starter mix (or loose, fertile, and disease-free soil) and pat it down until it is level but still loose. Each type of seed has a different sowing depth so consult your seed packets for further instructions. A general rule of thumb is to plant seeds twice as deep as they are wide. Place several seeds in each container, but don't scatter too many as overcrowding will inhibit proper growth. Don't forget to label what you are growing, especially if you have multiple trays of different seeds growing simultaneously.

4. Provide adequate lighting. To sprout, seeds need 12-16 hours of light, so growing them under a fluorescent light is ideal. A windowsill is not an option even in the sunniest spot in your home, as late summer or early spring has unpredictable light at best—and usually not 12-plus hours' worth. Most gardeners agree that a 40-watt fluorescent light works well.

5. Control the temperature and humidity. Make sure the room temperature is regulated as well, ideally between 65 degrees and 70 degrees Fahrenheit for most seeds (consult your seed packet for specific instructions). An easy way to boost the temperature is to place a humidity dome over the plants or a heated mat under the plant trays. Make sure to maintain adequate moisture levels; soil should be damp, but not drenched. No fertilization is required during the germination period. If you are using any artificial heat, remove it when after the seeds sprout their first leaves.

6. Start thinning. Once your tiny plants start to sprout, it's time to show some tough love. Thinning might seem like a waste of a healthy plant, but it is a necessary step to help your seedlings become strong and healthy. To thin, clip the weaker sprouts at the soil level, as pulling them out can damage the delicate root systems. At this point, give the seedlings a half-strength fertilizer that is specific for houseplants about every two weeks.

7. Upgrade your containers. When several inches high, it's time to carefully transplant your seedlings into bigger containers. Try using some peat pots, as they are biodegradable and can be planted straight into the garden when outdoor conditions are appropriate.

8. Acclimate your plants to the outdoors. The final step is to transition your plants into the garden, a process called “hardening off.” After the threat of frost has passed, take your little seedlings outside for about an hour, in an area that is sheltered from the sun and wind. Gradually increase this time and exposure to the outdoors over a two-week period until, finally, your little plants are ready to be planted into the garden—ideally on an overcast day. (If you purchased seedlings from a store, ask the seller whether or not they were hardened off, though assume so if the plants were outside when you bought them.) 

9. Transplant your plants into the garden. Whether you are planting seeds directly into the soil or transplanting seedlings, consult your seed packet for sowing depth and spacing. (or, as a general rule, dig a hole that is twice as wide and deep as your transplants). Handle your seedlings carefully because, essentially, they are delicate babies.

10. Care for your new plants! Seedlings and directly-sown seeds require TLC once they are in the garden. Watering them regularly is important as they are in their infancy and not yet "established." Protect them from wind and predators (birds are notoriously munch on freshly planted seeds). Mulching around plants, once established, is a helpful way to increase moisture retention, too.
Click here to to redeem your SparkPoints
  You will earn 5 SparkPoints

Member Comments

Thanks for the info. Report
thanks Report
Thank you Report
Thanks for valuable recommendations. Report
Good, clear advice. Thank you! Report
Good info Report
This year is my first attempt at gardening. I have read tons of books and articles online and a week ago finally planted my first seeds. I had lettuce pop up within about 2.5 days, same with convolvulus. The remainder except the daisies which have not sprouted at all were peeking through around day 5. Last night I transplanted the seedlings that were ready into larger growing containers (I used red solo cups with holes poked in bottom) and gave them some water with 50% strength fertilizer in it. It has only been about 14 hours but I can happily report the leaves are darker green in color and all transplants seem happy in their temporary home. I am loving the gardening and learning about it has been just as fun. I am blogging my misadventures As a journal of sorts. feel free to check it and any feedback is greatly appreciated.

nation-fingers.html Report
I always seem to have problems starting from seeds. My plants get leggy and I either start them to early to plant out doors or when I transplant them to a larger pot they die. I just find it less stressful to just buy them. I keep trying but I must be doing something wrong. I even thought it could be my water. Will have to try again. Report
I invested in a special grow light system a couple of years ago, and want to upgrade next Winter. It is more economical, and a new fun skill to learn. Report
My garden has started looking pretty lush this year. Last year it was quite sparse with a few Zucchini taking over the whole plot. The experience I gained however gave me the skills to plant the right plants this year and produce a good yield. Or it could be that I just got better seeds this year.

-seed-mixes.html Report
Appreciate the tips! I was shocked to open my seed packets recently and find so few seeds. One only had three seeds in it!! I went back to the store and the rest of similar packets only had six. Planted same flowers last year from one packet. Arrgh!! Like so many other things.. price is up and packages are smaller. Makes careful starting even more important. Report
I love my garden. Can't wait for the summer to come. It look so pretty when they coming up. But this year I want be able to have a garden because I am having a right shoulder replacement. Report
I am new to SparkPeople and am in the process of learning to navagate the website. I am really excited that I found this article. I am also a new retiree and am looking for activities to fill my day. I'm into this one!!!

Thanks Report
Regarding the tickleme plant. I have one in my classroom. My student is the asian girl sitting on the front steps in the commercial! I'm soooo proud of her. At the beginning of the school year she brought me the plant starter kit. It's so cool! Report


About The Author

Jenny Sigler
Jenny Sigler
Jenny is a stay-at-home mom to her young children, Augustine and Olive. An avid gardener and baker, she enjoys writing about health and childcare topics to empower people to make healthy choices. See all of Jenny's articles.