The Courier-Journal (Louisville)
Want to grow vegetables from seeds indoors? Here are 5 things to know
There has always been something magical to me about growing plants from seed. Growing plants from seed and then harvesting produce from those plants is even better. Saving a few seeds and starting it all over again the next year ... hard to beat!
But as with many opportunities we encounter each day, we tend to overcomplicate, overthink, and in too many cases, just throw up our hands and go to the farmer’s market for the week’s fresh produce. Not that I have anything against the farmer’s market. It’s just that growing your own produce carries a special kind of magic.
And since now is the time to get to work if you’re serious about starting your own, this seems like a great time to hit the basics. Here are a few things you need to know to successfully grow plants from seed indoors.
Where should I buy plant seeds?
You just can’t grow good plants from bad seeds. And good seed comes from good sources. Visit your local garden center where they probably know the people who produced the seed in those little packets. Or, you can go online and scour reviews ... be sure to look for the reviews beyond those first few pinned to the beginning of the list that say things like, “I loved my purchase and am very happy with my product.”
And talk to your gardening friends. Everyone has their favorite source, and most gardeners are happy to share their favorites. You might even get lucky and find a garden friend who saves their own and might be convinced to share.
What is the best starting mix for indoor seedlings?
The stuff you use to fill your germination trays should be different from what you pot them up in later. A good germination mix has no mineral soil, a very fine texture, a low nutrient content, and is consistent and uniform. The fine texture ensures you get good contact between the seed and the moisture-holding mix.
A mix that is too coarse makes germination more difficult, especially for some very small-seeded vegetable varieties.
How often should I water my indoor seedlings?
This part takes a delicate touch. It’s easy to overdo it or underdo it when it comes to watering through the germination process. That’s why so many people use clear plastic domes over their germination trays. The domes keep the humidity high but allow light to pass through.
The tricky thing is that a high-humidity environment also makes a great home for pathogenic bacteria and fungi. So the general recommendation is that as soon as your seedlings begin to emerge, it is a good idea to start to gradually prop up the dome a little more each day to let some fresh air get to the plants and reduce disease pressure. Some people have good luck replacing the clear plastic dome with a damp paper towel placed over the seed tray. A spritz of water from a misting bottle will maintain that high humidity environment but is hard to make that work if you aren’t home for a full typical workday.
How to use a seedling heat mat the right way
If you’re like so many of us who try to garden and also have a home that doesn’t look like a root cellar, it’s not uncommon for the seedling setup to be relegated to the cool, drafty basement. And tomatoes, peppers, eggplant, and okra don’t like anything that even rhymes with cool or drafty!
The best solution for keeping your seed and newly emerging seedlings nice and warm in a cool basement is the use of a heat mat. These electric-powered mats have a thermostat that allows you to dial in the perfect temperature for your particular crop. And as a bonus, most homeowner-focused heat mats print crop-specific tips right on the mat. But one thing to watch is the combination of heat mat and clear humidity dome over your seedling tray. A little experimentation goes a long way to make sure you don’t cook your seedlings. Some heat mats come with a sensor that you can stick under the dome. That makes everything much easier.
How much light do seedlings need every day?
This is where things get trickier. First there are germination light requirements. Most vegetable seeds will germinate in the dark. For those, a simple covering of about one-quarter-inch of your germination mix will provide the right environment. But there are a few that will not germinate in the dark. Lettuce and dill are the two most prominent examples. For those, sprinkle the seed on the surface of your germination mix, press gently into the surface and then mix gently with water.
But the real mess comes in the form of what kind of artificial light you need to produce healthy and strong seedlings. Modern LED lights have made for zillions of choices and enabled pinpoint specificity, but they have also opened up a confusing mess.
LED lights are rated by their power (wattage), their light intensity (lumens) and their color (kelvins.) And to put it mildly, if you were to assemble a group consisting of a theoretical physicist, lighting manufacturer marketing director and a home gardener and lock them in a room to discuss lighting, you’d probably want to make sure that there were no sharp objects in the room. So, I’ll try to keep this simple. There are LED lights made specifically for growing seedlings. Those are perfectly fine. They are heavy on the red/ blue wavelengths of light which is good for growing plants. They can also be quite expensive. Then there’s the garden variety LED shop light. These include a bit more in the green part of the spectrum which is most beneficial to plants in the seedling stage — less so as the plants mature. Shop light-type LEDs also tend to be much cheaper. So, Shoot for something around 40-50 watts and 4,000-5,000 kelvins and you should be fine.
Finally, light placement. Because even the most advanced LED lights aren’t the sun, place your light source just a few inches above your seedlings. You’ll have to raise the light source as the seedlings grow so an easily adjustable setup is best.
And just to help keep all this from feeling overwhelming, if you give it a shot and the magic just doesn’t flow the first time out, don’t fret. There will still be plenty of time to go out and buy some transplants for the coming season.
Paul Cappiello is the executive director at Yew Dell Botanical Gardens, 6220 Old Lagrange Road, yewdellgardens.org.