Successfully start seeds indoors for spring planting using small glass jars! Small glass jars covered with plastic wrap create “mini-greenhouses” perfect for starting tomato and pepper seeds for your spring garden!
This post contains affiliate links. Read here for disclosure.
Save Money by Starting Your Own Seeds
Gardening is expensive. One way to save a lot of money is to buy a $4 packet of seeds and start your plants indoors. Right now greenhouses and nurseries are preparing for spring and summer sales by starting their seeds. They want plants ready to sell and be put into containers and into gardens.
You can do the same thing on a much smaller scale. Here in Iowa, a sweet red pepper plant at the garden center costs about $3. A packet of about 25 sweet red pepper plant seeds costs about $4. Even at a 50% germination rate, you’ll get 12 pepper plants for $4. Buying 12 pepper plants at the garden center will cost $36. That’s huge savings! If you don’t use 12 pepper plants, just compost the ones you don’t use, or plant fewer seeds.
I have two huge vegetable gardens and I do plant 12 pepper plants so any savings are welcome.
NOTE: These photos are from last year. I planned that far ahead for this post because I wanted to show you the new little seedlings in time for you to get your seeds started for spring planting. I was concerned that waiting to show you seeds starting from this year would put you behind. So if you live in an area where planting happens in Mid-May, you will want to start your sweet pepper seeds now.
Make Mini-Greenhouses Using Jars
To start my seeds I use empty Oui yogurt jars, regular potting soil, and Glad Press n’ Seal. You can use just about any empty glass jar such as a Mason jar, pesto jar, or baby food jar. The idea is to create a “mini-greenhouse” with each jar.
How to Make Mini-Greenhouses for Starting Seeds Indoors
Cover an area where you will be working with a fresh plastic trash bag or a paper grocery bag cut open to lay flat. I’m using a white trash bag because my granite countertops are black and the photos for filling the yogurt jars won’t turn out at all on that dark background. 😊
Have your seeds, potting soil, Press n’ Seal, scissors, a spoon, and water handy.
Using a spoon, fill each jar about 2/3 full with potting soil. Place about 4-6 seeds on top of the potting soil in each jar. Then water the soil to the point it is wet, but not sopping wet. You just want the soil good and moist. Next, tear off some Press n’ Seal and cut it into squares large enough to cover the top of each yogurt jar. Place the Press n’ Seal over the top of each jar and press it well to get it to stick. Then use your scissors to poke several holes in the plastic cover.
This creates a good balance between holding in heat and moisture and letting the soil breathe.
Where to Place Your Seed-Starting Mini-Greenhouses
Then set your “mini-greenhouses” in a sunny window sill or any place in your home that gets at least 4 hours of direct sunlight and stays warm consistently. My guest bedroom has an east-facing window that is a perfect place for setting these “mini-greenhouses.”
Since all seedlings look alike at the beginning, I label them so I’ll remember what plants are being started in what jars.
This year, I don’t have any Press n’ Seal on hand, so I cut squares out of a clean, used clear plastic storage bag. I used rubber bands to hold them over the tops of the yogurt jars and cut a small hole in the center with scissors. This works well, too.
How Long Does It Take to Start Seeds Indoors?
Germination should take place within 10-14 days. Sweet pepper plants take a little longer sometimes. They are a slow-growing plant so I start them in January to have them large enough to plant in the garden by Mother’s Day.
Tomato plants grow faster, so I’ll wait until mid-late February to start my tomato seeds. Basil and other herbs tend to grow pretty quickly so I’ll wait until late March to get them going for outdoors. I just started some basil seeds for an indoor pot for my kitchen. They haven’t germinated yet.
This method works for flower seeds as well. I wish I had room in my home to start all my summer flowers as well as my vegetables. Wouldn’t a small greenhouse be wonderful?
Dividing Your Seedlings
Once your seedlings get too large for the glass jars, they’ll need to be divided or their roots will bind up. This is where those empty cottage cheese containers, some unused 6″ diameter flower pots, or even wide-mouth Mason jars come in handy. I like empty cottage cheese containers because they don’t have holes in the bottom. I don’t need a tray to catch water draining from the hole in the bottom with cottage cheese containers. They’re also easy to flex to loosen the soil when I’m ready to remove the plants to put them in the garden.
To remove your seedlings from the yogurt jar, carefully loosen the soil around the edges with a spoon. Then holding the plants toward the bottom with one hand, turn the jar upside down with the other hand and gently tug the plants to pull them out.
Don’t worry if the roots are a tangled a little. Just gently press the soil around the roots back and forth to get the roots loosened and pull them apart. The little plants will be okay. Then plant them into fresh potting soil into the larger containers.
Why Not Start the Seeds in Larger Containers?
I like to use clear glass jars for starting my seeds because they’re clear. More sunlight reaches the seeds to nourish and warm them. They look nicer in my window and the plastic wrap clings better to glass than it does plastic. The larger seedlings don’t need the “mini-greenhouse”.
After diving and replanting my seedlings, I wash and store the glass jars for the following year.
When Seedlings Are Ready for the Outdoors
I like for my pepper and tomato plants to be at least 4 inches tall before placing them outside. They need to be large enough to withstand rain and wind.
How to “Harden” Your Seedlings for the Outdoors
Seedlings started indoors need to be “hardened” or toughened up before placing them directly in an outdoor garden or container.
About 2 weeks before you want to place them outdoors permanently, set them outside on a porch or deck for a few hours a day each day. Water and fertilize them before doing this. Then bring them in at night so they don’t get too cold. When the weather is warm during the day and stays above 40° at night, it’s safe to put pepper and tomato plants outdoors in a garden or large container permanently. If you compost, be sure to till your compost into the soil before planting.
What Garden Seeds Can Be Started Indoors?
Just about any plant that grows best from a seed rather than a cutting can be started indoors. I like to start tomatoes and peppers indoors because starting them from seed outdoors where I live is risking not getting any fruit before the fall frost.
I don’t bother starting seeds from any kind of squash or cucumbers because they grow fast and do just fine seeding them right into the garden soil. Start row crops like dry and green beans, sweet corn, okra, etc. directly outdoors in the garden soil. I did start some fennel indoors once, but when I put it in the garden the rabbits feasted on it. 😠
Petunias, impatiens, and marigolds are great flowers for starting as seeds indoors.
Why I Like This Method for Starting Seeds Indoors
I’ve tried using the plastic trays for starting seeds indoors, but they need constant watering. They take up room I don’t have in my house. I do have a large window next to a landing in my mudroom, but it gets too cool in there sometimes and even with a heating pad under the tray I had limited success.
Plastic-covered glass jars give me the greatest success with starting seeds indoors. This method is easy, it takes up a window sill or two, it’s not unattractive (I’m not crazy about cottage cheese containers in my window, but they aren’t there long), and it requires no special equipment.
Let me know if you have any questions! What plants would you like to start indoors for spring planting?
FREE Home & Life Calendar!
Subscribe to get our latest content by email, and enjoy a free Home & Life Calendar that includes a monthly checklist of home and life related activities to help you stay organized.