how to start seed indoors

Broccoli seedlings NO GREENHOUSE, a tiny house, and various other obstacles notwithstanding, I’m madly coaxing along one crop after another of seedlings over here. Want a little tour of how to start seed indoors (well, at least Margaret’s improvised method, that includes some outdoor steps, too)?

My house is too small for make room for grow-light stands and seedling flats, and you wouldn’t want to even think of climbing down the ladder into the cellar here a couple of times a day to care for seeds. No matter:

seed starting outdoors I improvise. My “potting bench” (above) is the backyard on a fair day, where it matters not whether potting soil goes astray. I simply bring all my supplies out, sit on a footstool and make my mess.

Important: I lightly pre-moisten the germinating mix right in the bag a day or two before, massaging it and turning it a couple of times to let the water I’ve added absorb evenly.

1:10 bleach:water bath for re-used flats and cellpacks

If I’m re-using nursery pots, flats or cellpacks, I wash them first in soapy hot water or a 1:10 bleach:water solution (above, cellpacks soaking).

Once the flats are filled with the barely damp mix and the seeds are sown, I let the sown flats, fiber pots or cellpacks wick up more moisture from below, setting them briefly in a dishpan or roasting pan of water. Seeds want to be very moist to germinate.

The electric germination mats and lights are waiting in a nearby shed that has just the tiniest amount of electric baseboard heat. The heat mat set-up (below) is simply a partial piece of plywood balanced on top of a storage bin, set underneath a table. On top of the table: a light stand, one of two I own (the smaller one is two photos down below). I keep the shed in the low-60s F at this time of year. Primitive at every step, perhaps, but effective.

seed trays on heat mats

I put the well-watered seedling containers in waterproof flats, covered with plastic wrap or plastic bags or lids, and set them on heat mats just until the seeds begin to germinate (important: no bottom heat after the seeds sprout!). As soon as they show, I remove the plastic, and move them quickly to a spot under my T-5 grow-light hoods set on timers for 12 hours of light a day, and adjustable in height to shift as the seedlings grow. I keep the lights very close to the young plants–just a couple of inches away at most.

Adjustable T-5 grow-light hood and stand

I water more sparingly once they are up and growing, letting the germinating medium surface go just dry to the touch between waterings. I don’t feed until plants have true leaves, and when I do feed, it’s with a dilute solution of fish and seaweed emulsion.

seedlings outdoors

Once the seedlings have had true leaves for a week or so (and assuming the weather is not blustery) I carry them outside daily to enjoy sunshine and air all day. I set them in a spot near the house that’s bright but somewhat protected, especially at first; my bright back porch is good. Above, a few cool-season things on their daily outing.

Again: I do this only on fair days, but it gives the young plants more light than they’d get artificially, and also creates a stronger, stouter seedling that’s essentially being hardened off along the way. (A Cornell plant physiologist explains here how much stronger outdoor light is from even the brightest artificial bulbs.)

If you can’t carry things outside daily all along, be sure to harden off seedlings for a week or longer before transplant time. Put them outside by day, for a partial day at first, gradually increasing their exposure. To minimize shock, I like to transplant on an overcast day when it isn’t too windy, or best of all: just before a gentle rain arrives.

more help with seedlings

  1. Norma says:

    Thank you. I have copied this and as soon as we get to Minnesota it will be part of my garden notebook. This will surely get me started off on the right foot.

  2. Dianne says:

    What is your germinating mix made up of….commercial or your special mix? Thank you for the idea of moistening the mix in the plastic bag. Makes so much sense.

  3. Ellen Best says:

    Love your blog – so current with my own garden activities! Thanks-
    FYI, the garden calculator didn’t show up well on my iphone – (but I printed it from my computer – it’s great!

  4. mike burch says:

    hello there…i sure do enjoy your postings….thank you…I have 60 tomato plants planted and 70 different pepper plants planted here in Ocala,Florida..also have 50 squash plants planted …..my tomato varieties are burpee super sauce roma tomato,cherokee purple,burpee bigboy,steak sandwich,mortgage lifter,super beef steak,black krim,burpee brandy boy.,goliath,and golden jubilee…my peppers are poblano.joe e parker new mexico ,california wonder bell pepper,burpee early jalapeno,jalapeno,serrano,big dipper bell pepper,golden habernero,ghost pepper….zuchinnisquash,yellow crookneck squash and yellow straight neck squash.have small tomatoes on a few of the larger plants(about 14-18 inches tall)..i have grown everything from seed as well….and what a joy to see that miracle happening…..thanks again for your wonderful bolg

  5. Eileen J says:

    I found a great place for the flats of germinating plants: the bottom of a bathtub that is seldom used. There is a large window of thick smoky glass that lets in some light. When I need to water from the bottom, I just add a couple of inches of water to the tub.

  6. Bill says:

    That’s a great idea Eileen. We have a tub we are not using and that might work for us too.
    My seedlings consistently were too leggy this year, I suppose because we didn’t have the grow light close enough. Frustrating. Hopefully we’ll do better with our fall seedlings.

  7. Dyan Wapnick says:

    The new Pine Plains Seed Library is having a seed swap at the Pine Plains Free Library in Pine Plains, NY on May 11 from 2-4, with a talk on seed saving and the importance of biodiversity by McEnroe Organic Farm. Free. No need to bring your own seeds since we will have plenty there, but if you do we are asking for heirloom seeds only. Also, bring veggie recipes to share! Thanks.

  8. Sam Yachup says:

    All good information especially the part about getting the plants outside on days with fair weather. I define this as when daytime temperatures are in the 40’s and leave them out when night temps are not forecast to go below 40F. This goes a long way to strenghtening the plants and seems to reduce the incidence of damping off. And always keep in mind that the worst light outdoors is better than the best light indoors.

  9. During the week my typical day has me at work 10-12 hours so hardening off is impossible week days. So I need a cold frame I guess. But until I get one can they harden off in a hoop tunnel?

    1. margaret says:

      Hi, Rebecca. Do you have a slightly sheltered spot such as a porch or beside a building (on whatever is the gentlest spot — not baking hot or windy)? I sometimes just use my back porch (open, not enclosed).

  10. joanne says:

    I found this hint on the Empress of Dirt site. She puts seedlings outside in a tall sided plastic storage tub. The plants are sheltered from strong winds and I would think the sides also give some “warmth”. She suggests this be in a sheltered (covered) area outside at first. Under a roof. Against a wall. No lid, please.

    Easy enough to drag in and out of the house.

  11. Katie ridder says:

    I’m growing Verbena Bonariansis. So if I understand what you are saying, I use the heat pad only and no light until they germinate, 24 hours a day. Or heat pad and light during the day and no light and no heat pad during the night?


    1. margaret says:

      Hi, Katie. With most seed, the light’s not needed until AFTER they emerge (germinate), but with all seed, remove the bottom heat RIGHT AWAY when they do emerge. V. bonariensis is VERY slow to germinate, by the way. So when the seed shows itself, promptly remove the mat and plug in the lights.

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