Pretty red beetsPretty red beets
Beets and leeks in the backgroundBeets and leeks in the background
Spinach, Lacinato kale, Swiss chard, leeksSpinach, Lacinato kale, Swiss chard, leeks
Carrot seedlingCarrot seedling
Beet seedlings just after sproutingBeet seedlings just after sprouting
It's a fairly thick materialIt's a fairly thick material
They're basically big rolls of white feltThey're basically big rolls of white felt
Hello, capillary mats!Hello, capillary mats!
Our seedling grow op, before installing the additional lights and tableOur seedling grow op, before installing the additional lights and table
  • Pretty red beets
  • Beets and leeks in the background
  • Spinach, Lacinato kale, Swiss chard, leeks
  • Carrot seedling
  • Beet seedlings just after sprouting
  • It's a fairly thick material
  • They're basically big rolls of white felt
  • Hello, capillary mats!
  • Our seedling grow op, before installing the additional lights and table

Last year was the first time I’d really attempted starting seeds. I think I can consider it an overall successful attempt in that I didn’t buy a single seedling or start the entire growing season. Everything we grew came from seed or our own starts, including garlic  and sweet potatoes.

This year I’m trying to learn from last year’s successes and failures and improve the efficiency of our growing system. For me this includes getting things started much earlier, using more heat mats to help the seedlings grow faster and stronger, and in general just starting more seeds, instead of direct sowing.

I threw a ton of carrot and beet seeds out into the garden last year, and because I didn’t do a very good job of making sure the surface of the soil stayed moist (the one thing our soaker hose watering system isn’t good at), relatively few came up. So this year I’m starting almost everything inside.

I’ve invested in a few new pieces of infrastructure this year to make this scaling-up possible.

1. A new, bigger heat mat. Last year I only had one heat mat, and it was only large enough for a single flat. So far this year I have 12 flats planted already, so clearly one mat isn’t going to cut it.

I invested in a larger heat mat that fits 4 flats. Between the big one and the small one I still don’t have enough mat space for all my flats, but because of the expense of the mats I decided to just get the one big mat. I searched around quite a bit and found the cheapest price for a new Hydrofarm 4-flat heat mat on eBay.

We house our grow op in our basement, which is cool but not freezing (especially not this winter). These mats raise the ambient temperature by 10-20 degrees, which is just fine for my purposes. There are fancier systems with temperature control dials, but the simple on/off mats work fine for me right now.

To make the best use of space, I rotate flats on and off the mats and preferentially give some plants that especially need the heat (like tomatoes) permanent real estate.

2. Capillary mats. I just learned about capillary mats a few weeks ago, and after reading the rave reviews I decided to jump in.

Capillary mats are essentially a big piece of fabric that wicks moisture along the length of the mat. You stick one end of the mat in a bucket of water, set your mesh-bottomed flats on the mat and the mat absorbs the water and feeds it to the seedlings. This avoids over- and under-watering seedlings by keeping them evenly moist (and allows you to be lazy and forget about them).

I ordered 6 yards from Gardener’s Supply. When it arrived I was somewhat surprised to find that it looked like a big roll of white felt. It took some experimentation to figure out how to make it work, but after a week or two of tweaking, I think we have it figured out. More on that soon.

3. More lights. Our “grow lights” are cheap shop lights from Lowe’s (about $10 for a 48″ fixture that holds two bulbs). We suspend them from the rafters in our basement with chains so I can move the lights up and down based on the height of the seedlings.

To avoid the confusion of trying to combine bulbs with different portions of the light spectrum, I just bought full spectrum bulbs. We bought them in a bulk box and they came out to around $3 a piece. This means that you can put together a perfectly sufficient grow light with two bulbs for around $16, rather than the hundreds of dollars grow light systems online would like you to pay.

This year we bought two more sets of lights and the chains and fixtures to go with them. This allows me to have 12 flats (up to 576 seedlings in 2″ seed blocks) under lights at one time.

4. Another table. Our seeds and mats live on top of plastic folding tables. I guess we could theoretically just put them on the floor, but we’d have to have really long chains for the lights, the floor would become a mess from the water and soil, and the floor would be colder. Having them on tables makes them easier to work with.

To accommodate our increased number of flats and lights, we needed to also get another table to put them on. These aren’t cheap, but they’re sturdy and not bothered by the constant moisture that seed-starting requires.

So that’s the scoop. I have about 500 seedlings started already, and they are looking really good. I’ll probably need to start only one more flat of seeds (mostly cucurbits: summer squash, winter squash, cantaloupe and watermelon) before summer. And then of course it will be time to start seeds for fall and winter growing. But for now, 2012 is off to a good start!

12 Responses to “Scaling up our seed-starting system”

  1. pattyskypants
    17 February 2012 at 7:54 pm #

    Are you leaving the lights on all day or do you have a schedule? Any idea how much it costs?

  2. CoMo Homestead
    19 February 2012 at 1:31 pm #

    Generally 14-16 hours of light is recommended for seedlings. I have mine on a timer so they turn on and off themselves.

    I haven’t calculated up the cost, but that’s a great idea! I’ll try to get that figured out and posted soon.

  3. Joanna Reuter
    20 February 2012 at 12:45 pm #

    Do you have a fan going? If not, it might be a good addition. We found that out the hard way as we scaled up ourselves. Air movement really helps to avoid losses from damping off. Soil blocks are certainly less prone to damping off than cell-type containers, but not totally immune. We went for a year or two without any problems, then lost a bunch of tomato & pepper plants (in cells, granted); it was very sad. We’ve learned a few things since then.

    Also, mini blocks are a great way to maximize use of heat-mat space. I finally bought a heat mat this year, but of the smallest size because I can fit >100 mini block on one mat, and the brief period of germination is when the heat is most important (esp. for tomatoes & peppers). Our seedling area may have an overall higher ambient temperature than yours, though.

    Johnny’s also has 1.5″ soil blockers in a hand-held size now, too. Great for getting more blocks into less space and using less potting mix, for certain plants at least.

  4. Cheri Charleville
    20 February 2012 at 5:49 pm #

    I made my 4-tray seed warming mat with green board, styrofoam, rope lights, and an old shower curtain. Total cost was $4.86 for the sheet of styrofoam. Search instructables for the pattern and you can heat all your seeds without having to rotate them.

    I agree with Joanna about the fan. Not only does it help with the damping off, but the movement makes the stems of your plants stronger.

  5. CoMo Homestead
    21 February 2012 at 9:46 am #

    Joanna, have you considered a career in telling the future? :)

    I went and checked on the seedlings yesterday after seeing your comment and guess what? Damping off! AGGHH!!! I have never had this before, and you’re right, it is so very very sad. Looks like I’m losing two whole flats of onions, about 100 plants.

    After reading up on it, I can see that there are a lot of things I’ve been doing that could predispose the seedlings to damping off. It’s embarrassing to look back on some of the methods I’ve used in the last few weeks, knowing that I more than likely brought this upon myself. Uggh! Oh well. Onward and upward!

    I’m hopeful that my major indiscretions were restricted just to one week’s seed planting, which could be why the onions have been hit so badly and the other plants look good overall.

    I did set up a couple fans in the area, so hopefully that will help prevent any more losses. I’ve also read about chamomile tea being an anti-fungal agent, so I might try that also.

    I have thought about using the smaller soil blockers, but to me it seems like a pain to have to pot everything up multiple times. If I were growing thousands of plants and were more restricted in my space, I’m sure I’d use the smaller blocks. But for now I’d rather use the larger ones and be done with it.

  6. CoMo Homestead
    21 February 2012 at 9:47 am #

    Cheri – Very interesting! Thank you for the suggestion! I’ll definitely look at Instructables for the directions.

  7. Ozark Mountain Homegrown
    6 March 2012 at 9:00 am #

    I remember when I was a kid helping my grandma in her BIG truck patch garden.When she would direct sow seeds she would gently water them in, then she would lay wide plank boards directly over the row she just planted to keep the ground moist until they sprouted..She would just continually check under that board and at the first sign of germination she would remove the board so the seeds could sprout up and reach for the light.. I am sure that she used planks because they were readily handy, as my grandpa was a carpenter…The concept was that by covering the row with something heavy and keeping it dark with no air or light, it stayed wet and didn’t dry out…Grandma was a master gardener before there was even such a thing! She raised enough veggies to keep everyone in food through the winter!

  8. CoMo Homestead
    6 March 2012 at 9:20 am #

    Interesting idea!

  9. Simeon Wright
    21 March 2012 at 1:00 pm #

    Just discovered you website, looks great, lots of similar interests, will have to spend more time reading. A few comments on seed starting. Best way to deal with damping off is prevention. I have eliminated the issue in my spring seedlings through sanitation. You can try herbal antifungal agents, or even synthetic fungicide drenches, but that has never worked that well for me. Start out with a pathogen-free commercial potting mix and everything that comes in contact with it should be clean. That means new trays or cleaned and soaked in 10% bleach solution (damping off fungi are good at surviving on these items between plantings), and water seedlings with clean tap water etc. Plants should not touch “dirt” until you plant outside. Another thing to watch is how much water you give them. I will admit I cheat and give my seedlings too much water on warm sunny days when I know they will dry out, but I can get by with it because I’ve excluded the fungi that cause the damping off., Also, outdoors with seed starting would second the suggestion to use boards to protect seeds until they germinate. It’s the only way I can start fall crops during hot summer weather. I use some old rotting boards I’ve aquired that aren’t much good for anything else. My feeling is that the boards aren’t necessary during cooler, wetter spring weather and may be detrimental by keeping soil cool when you want warmer soil temps.

  10. Mike
    29 January 2013 at 4:00 pm #

    Just came across your web page, and saw this post. I’m an avid 2nd generation home gardener. After reading about your damping off probs and Simeon’s reply I wanted to add something I learned / always did growing up.

    If you are “reusing” soil for planting new seeds in, like Simeon writes you need to kill any fungi or bacteria. The bleach solution on trays and such is great, but what to do about the soil??? Short of buying new potting soil every year, which isn’t guaranteed to be free of baddies, try cooking your soil first.

    Sounds crazy I know, but since the volume of soil (even for 12 flats) is relatively small, collect your aluminum mixing bowls, and cake pans and bake your soil for about 30 minutes on your oven’s lowest setting. Just like Compost getting to 140F to kill bad bacteria, same here. Use a meat thermometer to check, but get it above 140F and Ta-Da, you have clean soil!

    I have no science background, but Dad always did it when I was a kid, and I’ve done it for years, never had a prob with losing seedlings.

    –Mike

  11. matt
    14 February 2013 at 1:14 am #

    I purchased a Hydrofarm mat that fits 4 trays. The plastic smell is overwhelming. Did yours have the same smell? Any idea how to get rid of it?


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