URBANA — As spring creeps closer and closer, gardeners start to get the itch to go outside and start digging in the dirt. While it may still be too early to do that, seed starting is a popular way to kick off the gardening season. 

Benefits of Starting Seeds

Seeds started indoors tend to get better germination rates compared to seeds started outdoors because the seeds are provided with ideal conditions. In addition to better conditions, they also won't have competition from other plants and there should be fewer insect and disease problems.

Starting seeds to have transplants can also be cheaper than going out and buying them later in the year. There is a lot more variety to choose from when starting from seeds compared to purchasing transplants from the store. 

Supplies for Starting Seeds

Fortunately, starting seeds isn't difficult. There are just a few things needed to get started: desired seed, a container to start them in, some growing media, water, and light.

Growing Media: Select a seed starting mix, not garden soil, as a growing media. Seed starting mix is sterile and is usually made from milled peat moss, perlite, coconut coir, and vermiculite. This combination provides a light, fine-textured media that is ideal for starting seeds.

Container: There are a variety of different options, from cell flats, plastic pots, peat pots, eggshells, and toilet paper tubes to egg cartons. Whatever choice, make sure it can hold media while allowing excess moisture to drain away, for example, drainage holes.

Lighting: Fluorescent grow lights are often used; however, regular fluorescent bulbs, a desk lamp, or even a windowsill works. If growing on a windowsill, make sure it has good western or southern exposure and isn't drafty. Supplemental lighting may still need to be provided. 

Seeds: Select preferred seeds and look at the back of the package. It will include growing information, including when the seeds should be sown. Example: X number of weeks before the last frost. 

How to Start Plants from Seed

1. Prepare the growing media: Pre-moisten media by mixing it with enough water so it holds its shape when you grab a handful but isn't dripping. Fill the container and make sure there aren't large air pockets.
2. Plant the seed: Make an indentation in the media to the recommended depth. Place 2 to 3 seeds inside this indentation and cover. Press the media down to make sure there is good contact with the seeds.
3. Cover the container: The container can then be covered with plastic to help retain moisture and warmth. Remove the plastic to spray the container if the media dries out. If uncovered, the media will need to be watered more often. Once the seeds begin to germinate, remove the plastic cover.
4. Keep them warm: If starting seeds in a cool area, it may be a good idea to get a heat mat that is specifically made for starting seeds so that the seeds will properly germinate and prevent disease problems. Once seeds have germinated, turn off or remove the mat.

As the seedlings grow, keep lights three inches above the tallest plant and provide them with 12 to 16 hours of light a day. Using a timer is helpful. Water media as needed, making sure it remains moist. Once the seedlings produce their first true leaves, plan to water them with a weak fertilizer.

As spring arrives, it will finally be time to take them outdoors and place them in the ground. Make sure to slowly harden them off before moving them outside permanently.

For questions on starting seeds, contact a local University of Illinois Extension office on the statewide map.

Ken Johnson is an Illinois Extension horticulture educator for Calhoun, Cass, Greene, Morgan, and Scott counties. Gardeners Corner is a quarterly newsletter from gardening experts around the state. Each issue highlights best practices that will make your houseplants, landscape, or garden shine in any season. Join the Gardener’s Corner email list at subscribe for direct access to timely tips.

Photo Caption: Trays of celery seedlings sitting on shelves under a grower light. Photo by Ken Johnson, Illinois Extension.