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Seed starting

March 5, 2009

And so it begins again.  Time to dust off the heat mat and start a few seeds.


I start my seeds in the greenhouse, without supplemental lights.  But I do provide bottom heat, which is very helpful to get a good start.  We have several of these heat mats – one holds two 10″ x 20″ flats and the other holds four flats.  My daughter is not doing her plant start business this year, so I can use both mats if need be.  I’ve also started my hotbed and I will write about that soon for those of you interested in off-grid plant starting in the late winter/early spring window.

I do a lot of succession planting, so this is just the first round.  But,  when gardening season gets in full swing, I can expect to maybe start a few seeds every two weeks.  Depending on light conditions and temperature, I may not need new plants every two weeks, sometimes I need them every week, or sometimes every third week.  So the biweekly schedule roughly works the best for me.  But, you can also waste a lot of seed, soil, and efforts this way too.  Just watch your plants in the garden and that will give you your gauge.  Lettuce getting bitter?  It’s going to bolt, you should have some already planted and close to harvest, that way you can make chicken feed of the old plants and ready the row for something else. 

You may notice that I’m using plastic pots and flats… , I have had these since we first started selling mesclun many years ago.  By storing them out of the light during the off-season, I will expect them to last another 15 years. 

I also use commercial potting soil for my seed starting mix.  But, if you are so inclined you could make your own.  Many gardening books have good recipes and supply lists. 

After filling the flats, I use my fingers to press down the soil to make a firm seed bed for the seeds. 

I used 6 packs yesterday for all my seeding.  Each flat holds 8, giving me 48 potential plants per flat.  For tomatoes and peppers and finer seeds I will use 200 cell flats, but that will be a later post.

I write the sowing dates on my seed packets, and transfer this information to my gardening log when I get back to the house.  I know this sounds quite unscientific, but  when I am going through my seeds, I can see at a glance what my prior planting dates were, and if the seeds are getting old and losing viability I can roughly tell by looking at this information.

Commercial seed packets have germination rates, and packing dates on them.  That information is vital to success.  Some seed lots may have lower germination rates and that will help you plan how many seeds per cell you want to plant.   If you are saving your own seeds, put as much information on the seed envelopes as you can.  It will be a great help later.

I, as a rule, use two seeds per cell.  This helps insure that I will have at least one live plant per cell.  If the seeds are old, as in the case of the mizuna seed above (1995 seeds, packed 1996), I may put 5 seeds per cell.  It’s early in the season and these old seeds may not come up at all this year, but I will at least give them a chance.  If I was growing these for sale, I probably would use fresher seed, but for home use, it isn’t the end of the world if I don’t have mizuna germinating this week.

I store my seeds in plastic shoe boxes, and keep them in a cool, dry, and dark place.  Look for a place in your house that the sum of the temperature and humidity add up to approximately 100.  Of course, strive for 50°F and 50% humidity or thereabouts, not 90 – 10.  Humidity is one of the biggies, so when we are done seeding, the seeds come back to the house – we never leave them in the greenhouse, even overnight.


After seeding and marking the 6 packs, I cover with more potting soil and water them well.  If you are planting very fine seeds, like some herbs, and flowers, etc., you may want to only cover the seeds with peat moss.  Some seeds need darkness to germinate and some need light, consult your seed packet or seed catalog for particulars. 

Since these are going in a unheated greenhouse I make a mini greenhouse by covering the flats with a recycled piece of greenhouse plastic.  On a sunny day I will have to monitor this for overheating.  Using a piece of rigid foam insulation helps to regulate the heat during the colder weather we are experiencing right now.

Here is what I planted yesterday:
Simpson Elite
Flashy Green Butter Oak
Red Sails
Little Sweets
Parris Island

Magma Mustard
Pink Lettucey Mustard
Space Spinach


Joi Choi bok choy
Melissa cabbage
Charmant cabbage
Ruby Ball cabbage

This will give us a good head start on our first vegetables of the season. 

Seed starting is an enjoyable part of the gardening journey, just start and don’t worry too much.  You may have some failures, but more than likely, many successes.  The failure part is how we learn, and the success part is what we get to eat! 🙂

15 Comments leave one →
  1. March 5, 2009 9:22 am

    I’m so hungry to start! I love looking at yours, and dreaming of next year when I’ll be able to get that “early start” on my season.

    I was interested to read in Gene Logsdon’s “All Flesh is Grass” about frost sowing… he says that for him, his lettuce seeded naturally grows faster than his greenhouse starts. I found that surprising…. and hadn’t heard about frost sowing before.

  2. March 5, 2009 9:35 am

    Nita, You referenced the type of flats you used to start your seeds. Does it matter what size the little cubbies are? Meaning, do I need to use a large size for one type of seed and a smaller size for a different type? For me, the novice gardener, one of the hardest things when growing my own starts is watering. I’m always concerned that I’ve overwatered at this starting stage, and then have a hard time determining when to water again. I’ve had mold issues, too. What is your watering method, and is there a good way to determine when to water? (Once the beasties are planted in the ground, I have no problems with watering. It’s just this beginning stage that trips me up, which is why I tend to purchase so many starts instead of growing my own. I want to give it another go this year, though.) Thanks!

  3. March 5, 2009 11:33 am

    Thanks for posting this, I am going to be starting some more seeds this weekend 🙂

  4. March 5, 2009 11:47 am

    Hayden, what Gene says is true, sowing dates and methods are all open to interpretation. When a seed germinates on its own and grows, there are no human imposed “interventions” like over and under watering, timing etc. The seed knows what to do and when to do it. But all that being said, my agrarian side takes precedence over my hunter/gather side and I plant to control the outcome, and yield. But, the plants that self sow in my garden, do far better than the same plants that I sow and tranplant myself. I have come to use those as an indicator to soil temps, so I can run out and plant and pretend I’m in charge!!

    Love the new pics BTW 🙂

    Paula, how long the plant will remain in the cell is what determines the size you use. Every thing I planted yesterday, is fairly cold hardy and can be germinated and grown with out re-potting in about 4 weeks. I will germinate my tomatoes, peppers, celery, celeriac and misc herbs in 200 cell flats. Once true leaves appear, I will re-pot, to fresh new soil and grow them on until after the last frost. So how’s that for a vague answer?

    Watering is tricky, I’m assuming you are starting seeds in the house, and it will be drier than my greenhouse conditions. So…generally speaking until the seeds germinate, keep your soil moist, but not wet, and after you see sprouting, you can let the top dry out, but not too much, since the seed is putting out it’s first baby roots and is very susceptible to drying out. On the other hand, too wet and you get mold or damping off.

    A humidity dome works good at first, and it can be something purchased or just a plastic bag loosely covering the flat will work. You can also water from the bottom if your flat can be place in a tray.

    Also remember that too frequent watering causes fertility loss in your planting medium so when you see your first true leaves you can begin watering with a weak fish emulsion, kelp mixture or you can also use compost tea.

  5. March 5, 2009 2:31 pm

    Thanks! 🙂 I’m not real familiar with your watering mixtures; I’ll look those up. Sooo much to learn … to soak the seeds or not soak the seeds, when to plant indoors and them move outdoors, figuring out which herbs/plants are annuals and which ones come back year after year, to fertilize or not, and if so with what. Ugh. Why didn’t I pay more attention to our bountiful family garden when I was a kid! Gee whiz, I took a lot for granted. I’m a quick learner though, and determined to make this work!

  6. March 5, 2009 5:43 pm

    The neighbor lady starts mine for me, she’s got a greenhouse and a greenthumb. She’s started already too but looking out the window today has me wondering if spring will ever get here. Happy birthday to the hubby tomorrow, I hope you bake him something good and think of me while your eating it 😉

  7. March 6, 2009 2:53 am

    Thank you for all the tips, I’m soaking it up as fast and as much as I can. Were the heat mats expensive? I have some seeds now starting that are in a warm place (well, sort of, about 70*) but will they still be too chilled to start? And since I don’t have a greenhouse….
    I am also worried about overwatering – do you keep the flats somewhat dry to start, and then add as the seeds become more established? I fear drowning mine and creating mold – they are so small!

  8. March 6, 2009 5:55 am

    Linda, I don’t envy you temperatures at all. Pie is on the menu! Happy BD 🙂

    Mangochild, if you’re starting your seeds in the house at 70*F you won’t need a heat mat. So your seeds won’t be chilled. The heat mats take the place of a warm room.

    As for the watering, the seeds need a moist environment to germinate, but that is where you have to develop your eye to judge between moist and wet. Once the plants emerge it is OK to let just the top of the soil get slightly dry. Bottom watering works well, and another way to water is move the flats to a place that you can water well and then let the flats drain and then put them back in their warm place. In the greenhouse we water with a hose or a sprinkle can and we put on a lot of water, but it can run out on the floor. It is hard to do that in a house. Hope that helps.

  9. March 6, 2009 7:02 am

    Lovely post! I just started tomatoes, peppers, eggplant, onions, broccoli, and cabbage yesterday. My set up is indoors, in our unused basement bathroom. I am new to succession planting, but determined to try it this year. So, you will continue to plant the brassicas inside, every other week or so for the next couple months? Do you ever direct sow those? What do you direct sow? Starting indoors or at least, in pots, seems so much easier in some ways–at least if you’re working at a bench you don’t have to bend over while trying to space itty-bitty seeds.

  10. March 6, 2009 9:18 am

    You inspire me. We have a radiant-heated floor in one of our bathrooms. Guess where my seed-starting is happening this year? Paddock Boy had to scrounge up a light for my tomatoes the other day as they were getting too big for the bathroom. They now reside in the living room. 🙂

  11. March 6, 2009 2:13 pm

    Hey Nita, I have a question that is totally unrelated to this post. I looked for an email address, but couldn’t find one…and I just plain do not know who else to ask about this!

    My husband and I now share a small “hobby-type” farm with my in-laws. It’s a homestead, basically. Well, My husband, Josh, is joining the Coast Guard and by the end of the summer, the babies and I will join him wherever they send us.

    My problem, is that my FIL was just laid off, so the in-laws want to get rid of all the animals here. [NOT including their three pet horses, of course, but that’s a whole different story] I am totally fine with that decision, because as we are leaving, it would be up to them whether or not to keep my animals. I only have three muscovy ducks and five polish hens. I’d originally planned on eating the ducks ANYWAY, but when it was time to harvest them, I was at the mercy of pregnancy nausea and knew I would not be able to handle it at the time.

    So, my question is, are the ducks and chickens too old to eat? They were all born in late July of ’08. And I’ve had them since. I don’t suspect I’ll get much meat from the Polish ladies, but I’d rather eat them than see them sold off as pets. What do you think?

  12. amanadoo permalink
    March 7, 2009 4:47 am

    Thanks! I’ve never used our pressure cooker before….this sounds like a fun reason to try it out. I never even would have thought about it….definitely time to learn how to use that sucker 🙂 Thanks again for the advice!

  13. March 8, 2009 7:38 am

    How exciting. I’ve been starting flats of things around here as well. What a great idea to write the sowing date on the packages. It would be nice if seed packets came with note areas on the backs for this kind of thing. Do you keep track of germination dates as well? I’m trying to do a much better job keeping track of this kind of thing.

  14. March 12, 2009 6:49 pm

    Where ever did you get the seed specific electric heating pads? (I’m presuming they are electric). I could definitely use some of those.



  1. Dropstone Farms » links for 2009-03-08

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