One delight of flower farming is seeing those little green cotyledons pop up through the surface of the soil. After a week or two of germinating cozily in their trays, they finally sprout into the visible world.
We start most of our seeds in indoor trays for a variety of reasons. First, earlier germination means earlier blooms and an extended growing season, especially for flowers native to warmer zones. Second, starting seeds indoors can help to create a consistent environment so that every seed has equal opportunity to germinate. Finally, with roots and leaves already growing, transplanting them into the ground helps them get ahead of the weeds competing for space, nutrients, and sunlight. Not all seeds need to be started indoors, however. Some varieties such as sunflowers, cosmos, zinnias, bachelor’s buttons, and larkspur can do their best work by being seeded directly into the ground.
Sowing seeds can seem a little intimidating, but it doesn’t need to be! There are a lot of different ways to get seeds germinating. That being said, let’s explore those methods.
Wet Paper Towel Method
This method is hands down the easiest, cleanest, and cheapest method of germinating seeds - and it’s fun because you get to watch! (This is also a great way to test germination rates of older seeds you may have stored.)
Zip-lock Bag and container
1. First, moisten the paper towel so that it’s nice and damp, and place it in the bottom of the container.
2. Sprinkle the seeds across the towel, leaving a little space between so that they don’t touch and spread potential disease.
3. Next, cover the container with the zip-lock bag to create a humid and warm environment.
4. Place the covered container in an area with consistent temperature, about 60-70 degrees and out of direct sunlight.
5. In about a week or so, those little seeds should be sprouting and will be ready to be placed in soil-filled containers. Tweezers are helpful for this stage as the seedlings are fragile.
Seedling Flats, trays or—Egg Cartons!
Many growers use plastic seedling trays and flats to start seeds. These come in a variety of cell sizes and are usually referred to as the number of the cells they hold – “128s” or “200s.” The smaller the number, the larger the cell size. Thus, 50s have larger, but fewer, cells than 128s.
Seedling tray or Egg Carton
Quality starting mix
Shallow pan or flat tray to catch water
1. Fill tray with moist soil, being careful not to compact the mix. It’s important to have a sterile potting mix to keep from getting diseases, as well as moist soil to start. Water doesn’t stick as easily to dry soil, which means it might carry your seeds away if you water overhead. Many premade soil mixes are mixed with substances such as vermiculite and perlite. These are mined minerals that help with water infiltration and retention, as well as keeping the soil fluffy and aerated.
2. Placing an empty a tray on top of your filled tray, lightly press into the soil to create divots in which to place the seeds. Again – we aren’t trying to compact the soil, just creating a space for the seed to lay beneath the surface once we cover it up.
3. Drop 1-2 seeds in each cell
4. Cover the seeds with enough soil to match the length of the seed. Vermiculite can also be used as a covering.
Egg Cartons are a convenient and simple alternative to plastic trays! Just be sure to poke holes to allow for drainage. Setting the carton in a shallow pan or flat tray will help keep the draining water contained.
Zinnias and bachelor’s buttons are two varieties that do well directly seeded into the ground. Keep in mind that you may need to wait until the treat of frost is passed.
Pencil or similar shaped object
1. Dig a small furrow using a thin object such as a stick or pencil.
2. Place or sprinkle seeds in the furrow based on spacing requirements provided on the seed packet.
3. Press the seeds into the ground about as deep as the length of the seed, covering when necessary.
For larger beds, it can be helpful to mark each furrow by pulling string taught across the length of the bed. If you are looking for something quicker than hand-seeding, there are mechanical seeders available that dig the furrow, lay the seed, and cover it up in a quick easy motion. Some varieties may not need a furrow. Check out how we direct seed our sunflowers!
There are a lot of other tools and tricks to starting indoors:
Light is especially important when starting seeds indoors. If there isn’t enough light, plants will grow leggy and weak. Grow lights can be used to mimic sunlight when growing in an indoor space such as a basement. Automatic timers and adjustable fixtures are helpful in keeping the light consistent as the plant grows. While this grow light business sounds expensive and complex, it doesn’t have to be. We started seeds for years using a grow light stand we made.
Humidity domes are plastic lids that fit overtop of the tray, creating a damp environment that encourages germination in the same way the zip-lock bag over the wet paper towel does. Trays can be placed in a warmer room or on a heat mat to help create a damp environment. Remove the dome once the seed as germinated and popped through the soil surface.
Don’t forget to label your trays or plastic baggie so you know which plants are which. It may also be helpful to write the date and the number of seeds you are sowing.
When it comes to tiny seeds and dry soil, watering overhead can easily lead to water running off the surface of your tray, carrying the seed with it. Bottom watering involves allowing water to slowly infiltrate the soil through capillary action. Simply place your tray into a shallow pan of water and wait! Remove from water when the soil feels evenly moist and your tray heavy.
After weeks of growing in a safe and consistent environment, thrusting your little plants out into the harsh world can be shocking and life-threatening. Consider gradually modifying your lighting and other conditions to allow the plants time to adjust to their new environment. This process is called “hardening off”.
Date of Last Frost and Date to Maturity
Knowing when to start your seeds is just as important as actually starting your seeds. Starting them too late can mean later blooms. If they are started too early, they may easily begin dwindling as their roots become crowded in their small containers. When starting seeds, be sure to keep in mind the local date of last frost so you can plant them without the threat of freezing. 4 to 6 weeks in the tray is generally a good rule of thumb, keeping in mind the size of the cells; smaller cells will need transplanting sooner than larger ones. Date to maturity is the number of days it takes from sowing to blooming. It helps to consider when you want the flowers to bloom and count backwards to determine a proper seeding schedule.
No matter how you begin starting your seeds, have fun! Give yourself grace as you determine the best method for your home, troubleshooting when necessary and remembering that losing plants comes with learning. Any leftover seeds can be stored in a cool, dry place. Happy Sowing!