Starting seeds indoors is a great way to get lots of tender seedlings going while it’s still blustery and chilly outside. Here are seven steps to seedling success:
Editor’s note: Not all seeds need to start indoors at the same time. New Yorkers can consult this calendar to see when to start what. And not sure what to do with your new seedlings? Consider container gardening or finding a community garden near you. This compilation of links is also really helpful for city gardeners of all skill levels and the Brooklyn Botanic Garden even has a gardener’s help line.
Take some deep breaths. Until about 150 years ago, the vast majority of human beings arrived at this moment many times each year. Things often went wrong, for them as they surely will for you. And yet, your presence on the earth today is proof that even when things were done imperfectly they still often worked out. So, approach the task of seed sowing with openness and a sense of adventure: No matter what happens, you’re about to learn a lot about plants, the natural world and your own attitude. (I know, not exactly how you wanted to spend your free time, that last point.)
2. Choose a method and stick with it for a while.
There are countless media and containers—and labels and watering cans and gardening gloves—to consider for sowing time. You can start with a sterile soilless mix made almost entirely of peat moss and vermiculite, or one full of compost and rich microbial activity (I highly recommend the latter). You can start with plastic trays and cells; with tiny cow-manure compost pots; with leftover mini yogurt containers (with drainage holes punched in the bottom—don’t forget!); or with no containers at all when using soil blocks. You can place seeds into soil with a tiny little plastic seed dispenser thingy (it looks like a giant comma with a clear lid), an electric vibrating seed dropper (yikes!), a moistened end of a toothpick or your pinched fingers (I prefer toothpicks and fingers). The options are seemingly endless.
I suggest, however, that you pick one method and stick with it for a season or two until you’ve mastered it, figured out what you like and dislike about it and are able to make a conscious decision to try out a different approach. In nearly all cases, problems at the seedling stage are less related to containers, soil media or sowing method than they are to the temperature, light and air conditions.
If it’s your first year with a garden, the easiest route is to head to a garden center and pick up one of their seed-starting kits and a bag of organic potting soil specifically labeled for seed starting. The kits are fairly inexpensive and include all you need for successful growing of a small quantity of plants; the organic mix will get your seeds up and running with plenty of nutritious compost available to feed the young plants. You’ll probably find that these kits don’t make sense as you transition to a larger garden or more encompassing suite of crops, and at that time I would encourage a bit of googling to research seed-starting methods used by small farms and avid gardeners. (For those looking for this information right now, here are some links to get you started: newspaper seed-starting containers, seed-starting trays and peat pellets and lots more. Don’t drown in the information! No single method is perfect!)
No matter which system you choose, do be sure to consider that seedlings require fertile soil: If you start with a soilless mix, transplant the young’uns into good, well-composted soil quickly or provide a liquid organic fertilizer until transplant time. (This added consideration is why I prefer a potting soil with compost; McEnroe Farms makes a great one—the Lite Mix—that is available at garden centers throughout the Hudson Valley.)
Once you’ve picked your set-up and gathered materials, begin. Nearly all common vegetable and flower seeds are best sown at a depth that is approximately two to three times their diameter. It’s pretty easy to eyeball this, and once you get the hang of it you’ll do it intuitively. What it means is that tiny seeds, such as those for carrot, lettuce, basil and most herbs, need only be covered by one-eighth to one-quarter of an inch of soil—or even just a dusting. Brassicas need one-quarter inch to three-eighths inch depending on the seed size. Beans need a good one-half to three-quarters of an inch. And so on. The drier the conditions, the deeper you should plant, as seeds germinate best when they occupy the magical spot where the soil remains fairly moist but oxygen from above ground is able to reach them. When the ground is dry, the moist layer is lower and the oxygen travels easily through the dry layer on top; wet conditions call for the opposite treatment. Once the seeds are in place, water them in: Give them a nice good drink to allow the seed coats to soften and the process of germination to begin.
Note: If the mix you begin with is totally dry, it will need to be watered before sowing—with the most fine and steady mist you can create—as a perfectly dry soilless mix will often not moisten easily once in trays. Seeds sown into these conditions will often float off once watered.
It is all too easy for something to go wrong during the seedling stage. An emergency that takes you unexpectedly away from the house and your seedlings to wither; a power outage that zaps your grow light for several days; a curious cat that mistakes your trays for a litter box: All can spell trouble. The best insurance against it is to sow more seeds than you actually need. Don’t wait for experience to teach you this important lesson; just oversow from the get-go!
One important method of oversowing is to re-sow all your favorite crops sown on one date a second time two or three weeks later. This may not work for those with tight space restrictions—it’s even hard for us sometimes—but I can report that on many occasions the later plantings have been a happy blessing. One summer, a late-sown round of tomatoes staved off an early blight beautifully (young plants are often able to repel disease more easily than fully mature plants), while another spring, our second-round of young celery seedlings replaced some that perished when we failed to vent a cold frame on a lazy sunny day. Troubles come, and it’s wise to anticipate them.
The hard part is at transplant time, when, if all actually goes well, you’ll have plenty of extra seedlings that can’t make it into the limited space of your garden. Give ’em to friends or family, or sell ’em on Craigslist. There’s always demand at transplant time for healthy seedlings.
5. Provide warmth and moisture.
Once you’ve sown your seeds into your seed-starting medium, you need to move the container to a location that will allow the medium to be warm and moist. The warmth is very important: cool pepper seeds can take weeks to germinate, while those kept above 80 degrees will germinate within about five days. See this link for a great summary of the ideal germination temps for different vegetable types.
Achieving these temps can be tricky in a wintry home. In days gone by, the tops of fridges were a hair warmer than the rest of the house, but unless your refrigerator was manufactured in the 80s, this is no longer the case. In most modern homes, a heat mat or other source of low-power directly-applied heat is necessary to see swift and satisfying germination.
6. Get rid of warmth and moisture and course with bright light.
Once you see your first flush of germination in any batch of sown seeds, quickly get them out of the warm and moist environment you’ve provided for germination and get them somewhere a bit cooler and a lot drier. Too much moisture brings on the dreaded damping off and is one of the most common mistakes made by new gardeners. Most seedlings will do best if taken off the heat mat and let to grow on in the room-temperature air of your house. The only real exceptions to this rule are peppers and eggplants, which thrive in continued warmth for much of their young lives—not the mid-80s that make them germinate quickly, but definitely the mid-70s, which keeps them happy but does not allow them to remain too pampered and weak. If you can’t provide just the right conditions, don’t sweat it, and err on the side of room temperature.
Of supreme importance: Make sure the young seedlings get plenty of light. A sunny windowsill is almost never enough light. We all wish that our windowsills would do the trick, but the reality is that with very few exceptions, a window, even south facing, provides light that is too unidirectional and not ambient enough. It streams in upon the plants in one direction only, making them lean toward it and, as they stretch and strain, weaken. When you start to harden off these seedlings at transplant time, they will very likely collapse upon their first exposure to the elements. So, for starting seeds inside your house (not inside a greenhouse), you should consider a set of fluorescent grow lights to be de rigeur. Run them 10 to 12 hours a day (or more!), positioning the lights just an inch or two above the young seedlings. Be aware that these lights generate a little heat, so you should monitor the soil for drying out. Dry on top, moist a half-inch down—that’s what you’re aiming for.
7. Relax. Again.
Once you go through this process a few times you’ll get the swing of it. Behold the young life unfurling by your own efforts. Be grateful for it. Don’t worry to death over it. Taking part in gardening is all about stepping into sync with natural rhythms, which are in constant motion. Seed sowing is just one part of the process, and it is not a zero sum game. Sow some stuff in the coming week or two; sow more the weeks after that; more after that. In fact, once you understand when to sow which varieties, you’ll be sowing eight months of the year, along with transplanting, weeding, and—with any luck—harvesting. You give and you wait to receive. You receive and you feel grateful. You always glance ahead and consider what you can sow now for harvest later. Don’t lose sight of the dance and get trapped in the feeling that it’s all or nothing; there is nearly always something to be sown right now to improve your garden prospects, feed you and your loved ones fresh food and save on your grocery bill several months down the road.