Seed-starting Don'ts
It's almost that time of year
NOTE: This rather lengthy post is adapted from something I recently wrote for my Facebook garden group, which, of course, you are welcome to join if you have not done so already. The group is a notoriously helpful, peaceful and non-confrontational corner of the internet — plus occasional groan-inducing humor from the admin — if that kind of thing interests you.
Seed starting season is approaching — perhaps already here depending on where you live. I think it is worth reviewing some basics, for the benefit of folks who have never engaged in this black art. More to the point, I want to identify common paths to near-certain failure, so that newbies don't start skipping down the path to plant perdition, their resulting frustration foaming into a lifetime of garden cynicism and self-loathing, always emerging in antisocial ways at the worst times at cocktail parties. Nobody needs that.
Let’s start by answering a fundamental question: Why start your own plants from seed, when you can buy plants cost effectively at any garden center or big box store?
Well, truth is…
[Oh my, I interrupt this post with a cringe — remember that highly unfortunate “truth is” Facebook meme from years ago?. You know, people spilling their guts to a machine eager to profile them. Good times. <sigh>. I now return you to regular programming]
…I can’t construct a good answer to this question for most people. Oh sure, I can recite the benefits for you. Here:
Grow a lot of plants much more cost effectively.
Pick your varieties.
Control the timing.
Avoid tag-along weeds, creepy-crawlies and plant diseases.
No hopelessly root-bound seedlings whose life trajectory is already sealed.
Guaranteed organic seedlings, not hyper-stimulated by chemicals.
But I can just as easily counter my own arguments:
You don’t need a lot of plants.
You’re fine with standard varieties. How many people can really tell the difference between a “Big Boy” and “Better Boy” tomato???
The big box stores always have plants when you need ‘em.
What are the odds of infecting your garden with a seedling?
You can find seedlings that aren’t root-bound.
You stimulate yourself with chemicals, why not your plants too?
Look, if you find yourself sympathizing with that last set of bullets, then, sure, growing your own seedlings might not be a great idea for you. Just don’t blame me when your root-bound tomato plants take a month to emerge from their stasis borne of big box neglect, bear late and produce less than half of plants given happy childhoods.
Only you can decide if growing seedlings is worth it. Or, as the pharmaceutical ads say “Talk to your doctor to see if Soilempic is right for you.” I always wonder about those ads. I can’t say I’ve ever walked into a doctor’s office and said “Doc, is that ungodly expensive drug with the weird, consultant-generated name that I saw on TV — but have no clue what it’s for because they don’t really suss that out in the ad, which mostly features creepy, animated, postmodern line drawings — right for me?”
Anyway, I think this decision is more of a vibe thing than a rational analysis that you flesh out on a spreadsheet using Bayesian statistical methods. If you think about plants every day and they figure prominently in your salacious dreams, seed starting might be right for you. If you are impulsively drawn to any catalog that arrives in the mail with a plant on the cover, seed starting might be right for you. If you get out of bed and you check on your plants before feeding the dog (or your kids), seed starting might be right for you. If you’ve skipped at least one important business meeting because it’s the perfect afternoon to transplant lettuce into the garden, seed starting might be right for you.
These are the kinds of questions you need to ask yourself. If these questions seem dumb, my advice is to head out to the big box store. If you find yourself answering “Of course, dummy, who doesn’t?”, then read on.
ANOTHER NOTE: I am not covering winter sowing here because I am not an expert in that, but I do not mean to discourage people from trying it. It's a legit approach, and probably easier and better for many people for certain types of plants. But I grow seedlings the old-fashioned way -- indoors under lights -- mostly because I have always done it that way. It is definitely more complicated, with more potential failure points. On the other hand, you do get a lot more control over timing and other variables relative to winter sowing.
And so, for my fellow control freaks who want to start vast chunks of their garden indoors, here is my list of don'ts:
Don't start too early. This is the biggest mistake that new seed starters make. Early isn't good unless you have a detailed plan for how to keep larger plants healthy, which is out of scope for most newer gardeners. You want seedlings to be entering their prime at exactly the right time, which varies by plant and where you live. Join my garden group for endless discussions about this issue in the Mid-Atlantic. For now, just understand that early February is waaaaay too early to start just about anything in the Mid-Atlantic, unless you have a greenhouse or some other area where you can provide enough light and warmth for a lot of large plants. Onions might be an exception, as they tend to be fairly easy to manage. But there is still plenty of time for those too. On the opposite extreme, don't even think about starting curcurbits (e.g., cucumbers, squash, etc.) until mid to late April.
Annual flowers are a special case, though still subject to the same considerations. Vegetables tend to have optimal time windows — narrow periods when they tend to do well. In those cases, your concern is getting the timing right, vs. feeding the impulse to sow early. But many annual flowers bloom all season after they reach a certain stage of development, much like peppers produce all season. In those cases, there really is an advantage to starting early, if you can get away with it. This is why I sow pepper seeds in mid February. With these types of plants, there is at least a rational argument for doing what is necessary to start early. That argument begins to fall apart quickly for things like tomatoes.
Don't rely on weak natural light. Light and warmth are non-negotiables. Most home seedling operations require artificial light (either standard fluorescent shoplights or LED plant lights). Without sufficient light you will get "leggy", tall and spindly seedlings (see below), which often are not worth salvaging. “Bright” windows in higher latitudes in the winter generally will not work. Similarly, if you plan to grow in a cool basement, many seeds need a soil temperature boost, which means using a heat mat of some sort. Some seeds (like peppers) will not germinate at all in cool soil, and most seeds will germinate much better and faster in warmer soils.
I’m a “use what you have” [read: cheap] kinda guy, so I tend not to go out and buy specialty items. My seedling “heat mat” is just an old heating pad for humans. Such heating pads are inexpensive and work fine, if you hook them up to a cheap mechanical timer. And I’m still using the same shoplights that I bought in the early 90’s.
A few additional words about light. I prefer old-school fluorescent shoplights to those newfangled LED panels that they make specifically for plants. The latter will work, and I do own a couple, but I have found that they work best with more established seedlings — say, when you have larger pepper seedlings but it is still too early to move them outdoors to harden off. Shoplights are gentler, you can (and should) hang them very close to the plants, and you can simply leave them on 24/7 if you want (onions aside — an issue for another time). It is also vital that you provide light from the get-go. Seedlings will begin a sure path to dreaded legginess almost immediately, if they do not receive adequate light during the germination process. For example, here’s some failure waiting to happen:
Don't use peat pots. Yeah, this will be viewed as a controversial statement in some quarters, but I will stand by it. If you're serious about seedlings, do it the right way -- beg, steal, borrow or buy seed starting trays with the requisite cubes and drainage trays (those clear plastic tops are nice but not essential). Okay, don't steal them. But do get some. Don't use cardboard egg cartons either. Why, Tom, why??? — after all, they sell peat pots everywhere. Herewith is why they be anathema to you, saith the Bishop of Buckingham:
First, peat pots (and egg cartons) tend to get moldy. Once they get moldy, you have little choice but to live with it. If you like moldy plant roots, then hey, by all means, use peat pots. Second, you have no flexibility with transplanting to larger pots, if the roots begin to grow through the pots. The odds of you timing things exactly, so that the plants can go into the garden just as the roots emerge, are roughly zero. Which means… Third, you typically (assuming things go well) end up with root systems that are exposed to the air for days prior to transplanting, and are thus damaged from the outset of their outdoor journey. And, fourth and finally, the whole concept of the peat pot decomposing after transplanting is generally a damnable lie. In the real world, most peat pots do not decompose, and in fact mostly just interfere with proper root growth. Just say no. The stores want you to buy peat pots because you have to buy more every season. And, if I can be particularly cynical, you also will frequently end up buying seedlings later in the spring after the the whole moldy peat pot folly ends up in the garbage.
Don't start certain plants indoors at all. Beans are the classic newbie mistake. Others are questionable -- e.g., some would argue that starting curcurbits (cucumbers and squash) indoors isn't worth the trouble, and there is some truth to that. I do it anyway most years, because, well… I don’t know why. I just enjoy doing it that way. I suppose it lets me choose the best seedlings and space them exactly as I prefer. So maybe just chalk it up to control freakiness. But if you choose my path of obsessive-compulsive satisfaction, the timing thing is particularly vital. Do not start curcurbits more than three weeks before you plan to transplant them to the garden. For the Mid-Atlantic, that means no earlier than late April.
Incidentally, if you have young kids, feel free to start a few beans and cucumbers indoors, even a little early. I know, I’m contradicting myself, but it is in the interest of familial bonding, which comes first in Tom’s Hierarchy of Important Stuff. The seeds are large and easy to handle, they germinate quickly, the plants are easy to see, they grow quickly, and it’s a fun project. Sure, go ahead, knock yourself out. Just plan to quietly discard the overgrown and useless plants at some point, and re-sow directly in the garden when the weather gets warm. Or, if you’re a plant sadist, move a couple to the garden as an object lesson.
Don't oversow. This is an underrated don't. Most newbies plant too many seeds, and then don't have the heart to thin & discard, or the time/space to separate & replant. Figure out how many plants you want, then sow at most twice as many seeds (assuming your seeds are new -- the ratio can vary if you retain seeds over a multi-year period, as I do).
I have my own system for dealing with this issue (“separate and replant”), which is non-standard and more labor intensive, but it reduces wasted seed and optimizes the plants that I grow in both number and quality. Plus, it allows me to give away seedlings to fellow gardeners every year. I typically sow all the seeds that I need for a given variety in one or two cubes of a seed-starting tray. I let the seedlings germinate and grow a pair of true leaves. I then separate the crowded plants, and replant the best ones deeply into individual cubes. This ensures that I get the best plants, and I’ve found that replanting deeply like this produces stocky, sturdy plants. People always ask if I kill a lot of the seedlings this way (breaking the roots, etc.) The answer is no — in fact, I almost never lose any. If you handle the seedlings carefully, never grasping the stems, and separating roots gently, they do just fine.
The “accepted” alternative to this method, documented and re-documented in bad gardening books around the world, is to sow three or four seeds per cube and simply snip off the extras in each cube after germination. Pardon my bluntness, but this is lazy and dumb. You waste a bunch of seeds this way, and often end up with some empty cubes anyway.
Don't be seduced by by Big Gardening. When you walk into a garden store or department in a big box store, you end up in sensory overload. Every package seems like a great idea that you need to embrace. But listen to me (imagine I am holding your shoulders and staring straight into your eye -- I know, that's pretty creepy, but I don't mean it that way). There is nothing new under the sun. Yes that's a lie, technically, but as rules of thumb go in gardening, it's not bad.
You don't need complex, all in one solutions that cost $129. You don't need next generation fertilizers (or any fertilizers). You don't need scientifically formulated starter soils. You don't need any of that stuff. All you need is light, warmth, clean non-porous containers, and a disease-free soil mix consisting of sifted compost and perlite. I say compost and perlite because I've been using it for decades and I know it works. Can other formulations work? Sure. But you don't need anything complicated or "scientific".
Don't forget that seedlings grow. Yeah, that's obvious, right? Well, not to many people. Many new growers forget that seedlings almost always need to be transplanted at least once into larger containers. And you need to accommodate those containers, which will often triple or quadruple the space requirements. Suddenly that manageable group of plants ain't so manageable. Which leads to my final don't (for today)...
Don't forget to plan for hardening off. You can do everything right and have some great-looking seedlings in you properly-sized area in the basement or wherever. But all of those plants, without exception, will need time to acclimate to the outdoors. If you fail to do this, I guarantee that you will lose most of those prized seedlings, or at least end up damaging them and delaying your harvest or flowery display by weeks. You need to plan for a semi-protected area outdoors where your babies can grow up to face the world.
How you go about accomplishing this is typically a question of local conditions and budget. I happen to have a small gazebo attached to a deck. It is perfect for blocking direct light early in the process (direct light can burn the young and vulnerable plants early on), while still allowing plenty of indirect light that the plants need. So I keep the plants in a rolling mini greenhouse (you can get them online for about $50), which I park in the gazebo early on. I can open and close the flap of the greenhouse to protect the plants overnight. As the plants mature, I move the mini greehouse out to the main deck, where there is plenty of direct light. When I am done with the greenhouse later in the spring, it returns to the garage, where it serves as shelving for all of my seed-starting trays and pots for the balance of the year.
So that’s my system. You will need to develop your own approach to hardening off. Cold frames can be useful, but you need some ability to control the amount of direct sun early on — the most common failure point with cold frames is fried plants. Again, some way, somehow, you must harden off your seedlings. You can do everything else correctly, but it won’t matter if you don’t have a plan for this.
So there you have it -- eight things to avoid at all cost, whether you are new to raising indoor seedlings or have been doing it for fifty-five years like …well, some other person. A final note: If you decide to try this for the first time, and things don’t go as well as you might like, don’t give up. Most failures in seed starting can be traced to one of these issues, although there are a number of other lesser pitfalls to avoid. I jokingly called this a black art earlier, but it need not be that at all. The challenge is that certain issues are pretty close to non-negotiable, and are guaranteed failure points. I have tried to delineate those here. If you have a plan for each of them, you will likely succeed.
If you have any questions, feel free to drop me a note or ask a question in the comments, which I am opening up to all readers for this post.
Thanks for reading.