As a child, I learned at school one day that plants need carbon dioxide to grow.
So, I collected a soybean that had fallen out of my dad’s pocket (he’s a Midwestern farmer, so it was not uncommon to find a corn kernel or soybean seed lying around), and I found an old clay pot of my mom’s.
I filled the pot full of “dirt”, planted the seed a several inches down, and watered the crap out of it. Then, I sat and talked to it, because I learned that as a human I breathe out carbon dioxide and by talking to a plant I could be giving the plant “extra” carbon dioxide.
Needless to say, the seed never sprouted.
Now that I’ve “gotten my hands dirty” in the world of gardening, I have learned there are several factors involved in germination like depth of planting, moisture, temperature, aeration, etc.
In my soybean experiment as a child, planting too deep (I had a 12″ deep pot and planted the seed about 11″ deep–HA!) and using soil full of clay from the yard rather than an airy compost mix or soilless media (think potting mix or any of the other various mixes sold in stores) were probably major factors. Also, I flooded that pot continuously. Poor thing didn’t stand a chance.
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Why Starting Seeds Indoors Can Be More Successful Than Direct Sowing
I find that starting seed and transplanting works better for our flower farm rather than direct sowing into the ground.
Here is why seed starting is so important for my flower farm:
- I have higher germination rates when I start seed indoors.
- Transplants have an advantage on pests and weeds.
- My flowers tend to bloom sooner.
- I can control the environment (water, humidity, fertility, pests, etc.).
- It gets rid of the dreary Winter blues (seriously!)
Planting seeds directly into the ground (direct sowing or direct seeding) can work very well if you understand the needs of that seed and the rhythms of your environment. I don’t want to discourage anyone from that. But if you’re interesting in starting your seeds early this year, this article is for you. Onwards!
What Soil to Use For Seed Starting
Plant nurseries use various mixtures of compost, vermiculite, perlite, sand, peat, mulch/bark, and coconut coir to pot up or start their plants in.
The reason you don’t want to use plain soil from your yard or garden is mainly because of aeration and drainage. Every soil has a different texture, but a lot of soils are full of clay. Clay particles are small and like to smush together. More smushing = less pore spaces = less space for water and oxygen.
Also, soil is alive. There are likely millions of microorganisms in your soil, and when you try to start seeds with that very-much-alive soil indoors, you may be creating an environment that favors the plant pathogens in the soil versus the “good guys”. Most greenhouse growers will steam sterilize sand and soil if they’re using it in the greenhouse to mitigate potential pathogen issues.
Instead of yard soil, you will want to use a specialized mix that is fine in texture. The most common mix you will find will be peat-based or coconut coir-based and will be labeled as “germination mix” at the store.
There are also some compost based mixes that will work quite well. I’ve been experimenting with Vermont Compost Company’s Fort Vee Mix, and so far I’ve had great results. Some people are concerned about the sustainability of peat, so opting for a compost or coconut coir-based mix is a great way to make possibly a better choice.
Why you may need a germination mix versus regular potting mix
Specially formulated germination mixes are finer in texture than your standard potting mix. This fine texture is great for starting seeds because most seeds are tiny. And we don’t want the tiny roots that develop to have a hard time growing through the mix.
We also don’t want such large pore space that it is easy for the roots to dry out, either. Regular potting mixes are full of things like perlite (the white stuff) or bark which helps increase pore space and drainage. We want a nice, fine mix that holds onto just the right amount of water.
In the long run, this all really isn’t a big deal. I’m just telling you that a growing mix labeled for germination is your best bet if you’ve never sprouted seeds indoors before.
I like to sprinkle vermiculite on top of my newly sown seed trays in order to help hold a little more moisture, too.
Starting Indoors
When I’m starting my seeds, I like to use propagation trays that I buy in bulk on Amazon or at a greenhouse supply store. My favorite greenhouse supply stores are Greenhouse Megastore, Bootstrap Farmer, and Grower’s Solution. You can also buy these trays in hardware stores at certain times of the year. Bootstrap Farmer carries the thickest and most high quality trays I’ve seen in my time as a flower farmer (just FYI).
I prefer the 72-cell trays for most of my flower starts, but for perennials or very large-seeded plants, I prefer the 50-cell trays.
If you want to ditch plastic, you can also try your hand at soil blocking. You can learn more about soil blocking by watching my video here. With soil blocking, you make a one-time purchase of either a 3/4″ or 2″ soil blocker and some trays. No broken or warped plastic seed trays laying around.
You certainly don’t have to use cell propagation trays or soil blocks! I had to bump up my snapdragon starts in my first year growing because the field wasn’t ready, so I transplanted into large clear Dixie cups and poked holes in the bottom. You can use the bottom of milk jugs, yogurt containers, Solo cups, egg cartons, vinegar jugs, or make your own pots out of folded newspaper, too. Get creative!
You can also buy pots or trays that readily decompose. They are usually made of peat or cow manure, but there are other types that decompose that are made of recycled plastic.
The important thing to remember if you are re-using pots or trays is that you need to wash them up really good! You don’t want some sort of fungal or bacterial pathogen to kill off your baby plants. I usually spray them off and scrub them with a dawn dish soap and bleach mixture.
Seed Size & Planting Depth
Seeds come in all sorts of shapes and sizes. A general rule of thumb is that bigger seeds need to be planted deeper, while smaller seeds can often be scattered on the surface. People like to say that you should plant the seed the same depth as the seed diameter. Some people also say to plant 1.5 times the seed depth. So if the seed is 1/8″ wide, then plant 1/8″ to 1/4″ deep.
The bigger seeds (or irregularly-shaped seeds) that I make sure to plant below the seed-starting mixture (1/8″ to 1/4″ deep) are sweet peas, tomatoes, peppers, zinnias, cosmos, marigolds, and sunflowers.
Flower seeds that are really tiny that I place on the surface of my seed starting mix are snapdragons, amaranth, celosia, cockscomb, and lisianthus. These seeds are seriously tiny. Don’t cough or sneeze while handling them. Ask me how I know.
Some of these seeds are so tiny that I will moisten the end of a toothpick and pick up the seeds with the toothpick and place them on the surface instead of using my fingers to sprinkle them on the surface. This ensures I can space my seeds properly instead of plopping a bunch in one spot. The seed adheres to the moist toothpick, which allows me to pick up one seed at a time. The toothpick, in this case, would be called a “dibble”. You can purchase actual dibbles, but the moist toothpick trick works great.
Moisture
Another thing to remember about your little baby plants is that they need a nice balance of moisture.
When I’m starting seed, I fill my trays with moist seed starting mix and make sure the cells in the tray are filled evenly. Then, when my seeds are sown in the tray, I will cover the tray with Saran wrap or a clear plastic humidity dome that holds the moisture in until at least 50 to 80% of my seeds have germinated.
After adequate germination, I will uncover the little seedlings and begin bottom watering or misting when the tray starts to dry out.
To better explain bottom watering: Usually I have a general 1020 tray (no holes) that I set my cell tray or channel tray down into. These trays that are nested into the 1020 have holes at the bottom so that water can move in or out. I use a watering can to pour about 1/4 to 1/2 inch of water into the bottom 1020 tray. Then, as the seed starting medium starts to dry out, water will wick up into the cells of my propagation tray as needed. This ensures that the seedlings are not disturbed or wiped out by overhead watering.
Seed Starting Setup
My seed-starting setup is not complicated, but it may look like it is with all the electric cords. If you are going to have a more sophisticated setup, make sure to locate it next to an outlet or two.
Here’s my basic seed-starting setup:
- Sturdy shelves (mine are from Menard’s originally; they are 6 ft wide by 2 ft deep and have 4 shelves)
- Shop lights
- Heat mats
- Thermostats for heat mats
- Power strips with timers
I highly recommend thermostats for your heat mats to ensure you’re not cooking your seedlings. You can buy them separately, but I personally would not. The thermostats allow you to set the temps accordingly. For example, I usually set my heat mat temps from 72 to 75 degrees F for germinating most seedlings, but for things that like hot weather (like peppers), I will bump it up to about 80 degrees F.
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