Starting Seeds Indoors

You gotta love the Midwest. We have four beautiful seasons, giving us great appreciation for the warm days of summer. Unfortunately for us, those warm days always end too soon. And for plants with long growing seasons that need those warm sunny days, like tomatoes and peppers, our summers can be too short as well. For this reason, many gardeners, and the greenhouse, start our seeds indoors, weeks, sometimes months, before the last frost date. This process takes dedication and can be daunting, but when done right, you get to enjoy a tomato or flower that you grew from seed.   

To begin, you need to look at what you’re growing and the maturation date on the package of seeds.  Each plant is a little different with time it takes to fruit or bloom, as well as how cool they can handle outdoor temperatures. Flowers like pansies, violas and dianthus prefer the cool temperatures, so they can be started indoors as early as mid-December or early January to be planted outside in early March. Other plants, like tomatoes  and zinnias, can’t handle the cold temperatures and don’t want to be outdoors until after the last frost. These seeds you would start later. Zinnias grow fairly quickly, so to put them outside at the end of May or early June, you could start them indoors in late April or early May. Tomatoes need a little bit longer grow time, so these you would start in February. 

Once you have figured out which seeds you are going to grow indoors, and when you are going to start them, you need to figure out what you’re going to grow them in. Many people come in to buy new containers from us, but you can also use egg cartons or gallons of milk that have been cut in half. The important thing is to be sure you have drainage. 

When you are planting seeds, do not use potting soil but seed starting mix. This is lighter weight and helps plants get a jumpstart. Pure soil can sometimes cause problems with disease among seedlings, so the mix helps prevent this.  

Once you are ready to plant the seeds, follow the directions on the package regarding planting depth. Generally, the larger the seed, the deeper it’s planted. Many of our seeds at the greenhouse simply get scattered on top of the planting mix and then lightly covered. 

When you have finished planting your seeds, it is time to water. The key is to water gently, using a mister or a saucer method for watering. Until the seeds start to germinate, or sprout, the soil should be kept evenly moist and in the proper temperature, which can be found on the seed packet. Some seeds like to be nice and warm, between 70 and 85 degrees, while others like it cooler, 50 to 65 degrees.   

Many people place their planted seeds into a plastic bag until the seeds start to germinate. This helps add humidity, keep soil moist and regulate temperature. If you do this, just be sure to water the seeds as needed and to remove the bag once they sprout. 

Once you begin to see seeds sprout, put the new seedlings in a sunny, unobstructed south-facing window. Or set them a few inches below a plant light equipped with one warm and one cool fluorescent light. Use an inexpensive light timer to automatically keep the lights on 14 to 16 hours a day. 

Once the plants are large enough, transfer them outside to your containers or garden. If the plants are growing larger, but the final frost has not yet happened transplant them into individual pots so they have plenty of room to grow. This can be done by loosening the root and lifting the plant with a pencil and planting in a slightly larger container. 

While growing seeds is not hard, keeping them alive can be challenging. It sounds like a lot of work, but when you bite into that tomato in July, it will taste so much sweeter.