If you’re thinking of planting seeds indoors this year, but don’t know what to start them in or when to begin, then this article is for you.
The time to start your tomato plants indoors depends on the zone you live in. The lower the zone number, the later you need to start the tomato plants indoors.
Zone Planting Guide
Urban Farmer has this guideline listed on their page of when to start planting tomato seeds. If you live in zones 1 through 4, the time to start sowing your seeds indoors is in mid to late March.
Zone 5: Start the seeds in early March.
Zone 6: start seeds in late February.
Zone 7: Start seeds in mid February.
Zone 8: Start seeds in early February.
Zones 9 through 10: Start seeds in early to mid January.
Because each location is different, the average time to start those tomato seeds is 6 to 8 weeks before the last frost date. If you live in an area that has a long growing season, you can sow the seeds right into the ground. Wait until the last frost date before you do so.
Planting Containers
Find a container to start the seeds. You don’t have to go out and buy anything, recycle something you have in your house. So many things will work, like an egg carton, milk carton, small tin can, or one of those aluminum pie tins. If you bought plants last year and kept the plastic cell packs, you can use those also. Just be sure to wash them thoroughly before using. Our planter of choice is an egg carton or milk carton.
Prepare the Containers
Make drainage holes in the bottom of your chosen container, before you fill it with potting soil. I use a nail to make the holes at the bottom. Don’t choose a nail that is too big or every time you water, soil will run out the hole. A too small hole won’t allow enough water to drain from the soil. Water needs to drain away or the seeds and/or seeds will rot.
Plant the Seeds
Place the seeds 1 inch apart, or sow one seed in each egg holder if you are using an egg carton. With your finger, push the seed into the soil so it is 1/4 inch deep.
Water and Growing Location
Water the containers, allowing the water to drain away. Cover the sowing container with a piece of plastic. This helps the soil to retain moisture and it raises humidity. You need to find a warm location to place the containers. The top of a refrigerator works well, or if you have a heat mat, you can use that instead. The area should maintain a temperature of 70 to 80 degrees F.
Check the soil once a day for moisture. If the soil is dry, add enough water to moisten the soil.
Move Into the Light
Remove the plastic sheet when the tomato seeds germinate. Move the container to a bright location. Turn the tomato containers every other day to keep the stem growing straight. Water the soil to keep it moist, but not soggy. When the tomatoes are on their second set of leaves, transplant them into a larger pot. Many gardeners transplant them into 4-inch pots, but I often reuse the cell packs that I have left over from working at the greenhouse.
When all danger of frost is past, prepare the garden, and plant the tomato plants outdoors.
Sources:
Urban Farm Seeds: Everything Tomatoes
Plant Hardiness: USDA Plant Hardiness Zone Map