Getting Started with Seed Starting

First tomato plants of the season popping up

First tomato plants of the season popping up

It’s that time of year again!

This past Saturday, I gave a talk at Palladio Garden in Midtown Memphis about starting vegetables, herbs, and cut flowers from seed. As many of you are revving up for spring, I thought you might find some of this information useful.

You might wonder why on earth someone would start plants from seeds, when you can get perfectly fine transplants at any nursery or garden center. I like to start everything I grow from seed, because it is cheaper, I get more variety, and I can control inputs. That means I know exactly what went into my soil mix and on my plants, and I’m not left guessing as to what kinds of chemicals might be present.

Me with the very first handful of lisianthus I grew from seed. You probably can’t find seedlings for these stunners in your neighborhood garden center! It’s just another advantage of starting seeds yourself.

Me with the very first handful of lisianthus I grew from seed. You probably can’t find seedlings for these stunners in your neighborhood garden center! It’s just another advantage of starting seeds yourself.

Now, I know some home gardeners swear by the success they’ve had starting seeds in a little tray they picked up at a hardware store and leaving them on a sunny window sill. I’m here to squash those fantasies and tell you that if you’re committed to starting seeds at home, it takes a little investment. (Okay, so maybe saying that it is “cheaper,” isn’t exactly accurate. It can be cheaper in the long run!) To successfully and consistently grow healthy vegetable, herb, and flower starts, you need:

1) Trays. I like to plant into cell trays and set those cell trays in flat 1020 trays. That way, I can gently lift up the cell tray and pour water into the flat tray. The cell trays have holes in the bottoms of each cell that can soak up the water. This makes for a far less messy situation for starting seeds in your own home. Here is a link to Johnny’s Selected Seeds tray selection.

2) Germination Mix. Although some home growers say that potting mix works for their seeds, I like to use mixes that are specifically designed for seed-starting. My favorite is Pro-Mix with Mycorrhizae. This is a super fine mix, perfect for germination. Mycorrhizae are neat, beneficial fungi that grow on plant roots. It help extend the roots and aids in their nutrient uptake.

3) Grow Lights. This is where it can get pricey. I’ve seen people make their home seed-starting operation work with trays and clear plastic domes. It’s a lot of work, though. You have to keep the tray in a window and watch for signs of light deficiency. (That’s when your plants get “leggy.”) Then, you have to move them outside when the weather is nice. Then move it back in when it’s cold or rainy. It can be a headache! A grow light is the way to go for peace of mind and consistent seedling production. Here is a good option from Johnny’s.

Bok choy seedling grown in a Jiffy pellet

Bok choy seedling grown in a Jiffy pellet

4) Water pitchers and/or a sprayer.

5) A box fan and/or overhead fan nearby for air circulation. This will help keep fungal infections at bay!

6) Seeds, of course.

For indoor production, I also really like using Jiffy pellets. I space them out in a flat 1020 tray, and add enough water to keep them feeling damp, but not soaking wet. They’re nice, because the air is a natural barrier for root growth, and it can help keep your plants from becoming root bound. They’re especially nice for gardening with children, because they’re so easy to transplant.

It’s important to check the back of your seed packet for your specific crop’s seed starting specifications. Some flowers have to have light in order to germinate, so you shouldn’t bury them. Some crops like to be in warm soil, so you might want to invest in a heated germination mat. Most vegetables just need good seed to soil contact to germinate, but they’ll need good light as soon as they have sprouted.

Centaurea seeds are SO COOL.

Centaurea seeds are SO COOL.

Also, make sure that you’re not over-watering, as that can lead to “damping off,” which is a term for a fungal infection that can cause your seedling stems to shrivel and collapse. Good air flow helps prevent this, so make sure to have a fan nearby. Additionally, I dip my seed trays in a 10% bleach solution before reusing them to kill off any lingering pathogens.

If you are in or around zone 7b (where I am) and growing cool-weather crops like leafy greens, you can start those seeds now and transplant when it looks like your long-range forecast isn’t dipping below 30, provided that your plants have a few good sets of “true leaves.” For all of those wonderful summer crops, you’ll have to wait just a little while longer. Your seed packet will specify how long before the last frost to plant indoors, but for most summer crops, I wait until March 1st to plant indoors, and I transplant my seedlings outside between April 1st and 15th, depending on the weather. Crops like cucumbers, melons, and squash only need two or three weeks in a seed tray, so wait even longer for those.

If you are in Memphis and want to come to my next speaking gig, I am giving a talk at Palladio on April 13th at 10:00 am titled, “Incorporating Horticulture and Plant Science into the Education and Development of Children.” Also, my dear husband is giving a talk on April 6th at 10:00 am called, “Tree Law and Other Disputes Between Neighbors.” His wealth of information about the intricacies of tree law is always a hit!

You can drop any seed-starting questions in the comments below, or you can always send me an email at mary@thesouthernhorticulturist.com.

Happy growing,

Mary Riddle

Me with a gazillion seedlings.

Me with a gazillion seedlings.