Growing Strong, Healthy Vegetable Starts from Seed
I can’t fully credit luck to my garden harvests, though there are numerous times when I wish I could because I feel like throwing my hands in the air some days when people plead to learn, “How do you grow so much xxx?'“. I don’t have all the answers, and I know that falls short for people who are seeking knowledge.
In my heart of hearts I know it is more than just sheer luck. I know it’s experience, and for us that amounts to a collective four decades of growing and learning, and it’s the (now) innate process we implement to our land and our seed starting process that result in robust, healthy, and very productive plants. So I’m going to try to lay it all out for you, to spill my secrets, even the ones that are yet unknown to me. I will invite the keyboard to wander until I’m satisfied it has uncovered every last delicate morsel and peered inside each emergent blossom of this great mystery even I behold as a wonder.
To truly dig in, you must first start with the seed. Only the best seed will yield strong seedlings. We have our favorites, and I won’t go into detail on that here, but if you want some inspiration, head on over to my Resources page for links to the seed companies we support with fervor; none of these links are sponsored, I’m merely sharing who we rely on for the best quality seed out there, so you can save yourself the headache of low germination rates and only buy from the best.
So you want to have your best garden ever? I’ll join you on this venture, as each year we strive to do better. A seasoned gardener knows all too intimately that some years are better than others due to factors well beyond our control, but for starters, a lot of little things at the beginning of it all directly affect how strong your starts become. So I’m digging in to share my top tips we religiously implement that produce our hardiest, healthiest transplants.
The Glory of A Seed
Seed starting satisfies a lot of yearnings for me personally. First and foremost, to watch life literally erupt from a single seed, this ancient ritual, a world within a world waiting for the ideal conditions to flourish, this is the most fulfilling, humbling, and exciting thing about gardening. To nurture that seed through to maturity where it then produces an entire head of cabbage, floret of broccoli, pounds upon pounds of cucumbers, basketfuls of tomatoes, overflowing bounties of beans and cucamelons and all the rest is the deepest, most satisfying work there is. It feels more like a privilege than anything else to grow alongside my plants each year, learning as much from my time in the garden as any other form of instruction.
Growing from seed is so much a part of our lives that it takes over a physically large part of our living space from January through April - and we love it. Between snowstorms and arctic blasts of air, we huddle inside by the fire, watering our seedlings, bumping them up as needed, and making room for new seeds and more and more flats of seedlings. We tend to these starts daily, checking for health and keeping a watchful eye on new germination. Providing the ideal growing conditions — basically creating a microclimate inside your home — is paramount to strong, healthy starts. This careful eye and thoughtful approach is what makes the difference between healthy and weak starts. As do a few other key ingredients.
The Right Stuff
For us, seed starting begins with the best growing medium, good quality and ample light, and warm soil. These are the three essential ingredients to successful and healthy garden starts sown indoors. And for us, it is the combination of these three elements that produce our strongest, healthiest veggie and flower starts.
The Growing Medium
Our soil block mixture blends compost and a lightweight soilless mixture with a small percentage of garden soil. While it contains available nutrients from the compost, we irrigate with a low concentration of liquid fertilizer after the first set of true leaves appear.
Additionally, we maintain this light feeding schedule until they are transplanted into the garden, where we add our slow release complete organic fertilizer into their own transplant hole. On occasion, I will start seeds in potting soil and I typically amend it with about 1/4 to 1/3 compost before sowing. We like to ensure available nutrients are at the ready for our young plants and I hope after reading this you will, too.
Ready, Set, Lights
Lighting is another indispensable aspect to our seed starting setup and I’m convinced after over a year of sharing our journey with like-minded gardeners online is a large reason our starts look so strong and healthy. I shared a brief post last winter about our lighting setup. This is something I get asked about frequently as people share their seed starting woes with me, and it bears repeating here.
We use T8 fluorescent lights and leave them on all the time once the first seedlings emerge. Yes, that’s right. We bathe our starts in light, 24 hours a day, and you should try it, too. In a tray with multiple species and varying germination rates, this means some seeds may be exposed to light before germination, which we have never found to be a hindrance to our seed starting endeavor. Even things that require darkness seem to do okay, like calendula, because I am careful to bury and cover those seeds requiring darkness into the soil.
The other important aspect to our light setup is this: we use a 48” four-light ballast (see it here at my Amazon storefront) with half cool white and half warm white bulbs. This is a really important part of your light setup and as far as I’m concerned a non-negotiable for strong plants — you must use a mix of cool white and warm white bulbs as this gives a broader spectrum of light than either can do on its own, thus mimicking more effectively natural sunlight. You really need to bathe these plants in your mock “sunlight”. Just think about how much stronger the real deal sunshine is than a few fluorescent bulbs. In the case of fluorescent, more is better, though not all light is equal. I cannot speak to other types of lighting except fluorescents.
A four-bulb ballast is what we consider a minimum amount of light for two 1020 trays, the standard size growing trays. If you use fewer lights or not the right spectrum balance, your plants may become leggy due to insufficient light (the botanical terminology for this is etiolation). Fluorescent light loses its power rapidly the farther you get from it, thus keeping them as close to the light as possible will alleviate their desire to stretch toward the dim light; it may not seem dim to you, but if they are leggy, it’s too dim for them.
If you can, you should be bathing your starts in at least 2,000 lumens per square foot, with plants as close to the light source as possible, as mentioned above. With our setup, we produce almost 3,000 lumens per square foot. I recommend if you experience a lot of legginess with your starts, you should check your current bulbs and see how they compare to our output, and see if you can find a way to bump up the output. You can look up the lumens of your bulb by doing a simple google search.
To mitigate this, we keep our starts as close to the lights as physically possible without touching the light. It is okay if a plant touches the light, but ideally your starts are growing at similar rate (haha, let’s be real, that never happens for me!) and so you adjust the light for the entire tray. In reality, our lights end up at angles rather quickly; I try to seed trays thinking about germination rates and how my starts can thrive harmoniously under these lights until they are ready to be hardened off and then placed in the ground.
Let’s Get Cozy
Heating mats is the final and equally important key to healthy starts that we have been experimenting with over the past year. In previous years, we used a heat mat until full germination of any given tray and then would back the warmth off the seedlings and allow them to acclimatize to our living space, which we keep at a cozy 67.
Since last Winter we have been trialing keeping the heat mat on for our hot crops (tomatoes and peppers) for an extended period of time post-germination. My tomatoes and peppers are still under a heat mat and it’s been three weeks since sowing, and the tomatoes are thriving. We will pot them up into 4.25” newspaper pots in another week or so and they will get buried deeply when we transplant. They may need to head to our cooler basement growing location, in which case we have a very large heating mat and we definitely keep it on all the time down there (air temp is high 50s to low 60s).
I mention this because it is something a lot of well-well-respected gardeners use with their seedlings. At Seed to Fork, we don’t use fans, but I can definitely speak to their usefulness and you can decide for yourself whether or not you need this accessory. Many other garden gurus run oscillating fans near there starts to increase stem turgidity. This helps the plants develop strong stems and prepares them a little more for the real world, which, of course, is the end goal. Gently rubbing your hands over your starts every now and then does the same thing, and that’s how meet this need.
Do What You Can
In the end, remain realistic with your seed starting endeavors. Our first indoor seedlings were grown using only one two-light fluorescent fixture, and they were I’m certain predominantly tomato and broccoli starts (this was a long time before our cabbage craze arrived). We may have paired two lights together, which we propped up on cinder blocks on our kitchen floor. It was a humble and suitable beginning, sufficiently meeting our needs for our garden that we mostly sowed directly in the ground. As you know, gardeners evolve with each passing year.
We are in the process of designing a four shelf plant stand so we can get even more seeds started indoors this next month. Because, Winter is long here and we rely on our strong starts to push our growing season as hard as we possibly can.
We aim to mimic as closely as possible a sunny late Spring day inside our winter homes: warm, inviting soils to encourage germination and growth, sunshine — and lots of it, and healthy, nutrient rich soil that has ample available water. These are the essential ingredients for seedling success, and I hope you’ve found something useful here to help propel your seed starting to the next level.