Monday, April 5, 2010

Trays, Trays, and more Trays!

Wood trays with 2" blocks awaiting Micros

A common question asked in soil block agriculture is, "What kind of trays do you recommend?" Let's hammer this one out.
Soil Blocks are a recently developed seed starting medium used in the United States(earliest records indicate late 50's). Plastic was already well in control of agriculture at that time, and was convenient for starting seeds for most people and businesses. So, most of us continue to use plastic, as it's really a remarkable product. And, soil blocks fit quite nicely into the plastic regime of plant trays. But, you will notice that does not sell any plastic trays. Why? Plastic fosters dependence on foreign oil and costly processing and transporting, not to mention the entire environment becomes severely polluted with plastic byproducts in the solids, liquids, and gasses of our planet. We must forge new options and new ways to deal with agriculture, but let's not go too fast! Plastic is a very reliable soil block tray, and here's plenty of examples of styles and equipment from people who use them.
My favorite company, Seeds of Change, uses the amazing web-bottomed 17"x17" tray with a 2" lip. If you can find these cheaper, they're great, I love them and will use them in long greenhouses for micro salad production. The open bottoms air prune the roots and hold a maximum of 64 2" blocks. This is first choice among the salvageable greenhouse freebies. Then, you've got the most popular flat tray in the U.S., the 1020. It comes with holes or no holes, and we like the no holes so that water can sit in the bottom of the grooves for reserves and help keep blocks moist, but we LOVE the bottom mesh trays for air pruning.  1020's are cheap and easy and you shouldn't have to buy them, if you can find them free, almost everywhere! The major downfalls of these two favorites is that they will eventually break, and end up in the garbage, or hopefully, in the recycled bin. So besides "gardening with garbage", as the Research Farm puts it, what's next, Guru?
Next, this style comes from the Undeniable Ambassador of Soil Blocking, Eliot Coleman who brought soil block makers to the US agriculture scene, and his market farming techniques for masters. They're the old-fashioned style wood trays, made from 1/2" stock plywood bottoms and three sides of 1"x3" wood in any length and size you can dream up for your operation. This will create a custom system for all those handy enough, and willing to make them. The 3" side height is perfect for allowing the seeds to sprout while they can be stacked up as high as you like. See first photo. We still use these trays, because, frankly, we trained ourselves under the Eliot Coleman system, and the trays are lasting 8 years now. We did paint them with a white latex paint for light reflection and water resistance. Make them out of cedar or redwood if you've got it. Since, this is a research farm, new options and methods are being trialed, and we have hit on some real winners. Let's track them down in the order of least expensive with the most work, to the most expensive with the least amount of work involved. (Why is it always like that?)  (And, it goes for all of our commercial stand-up soil block makers we sell!)

Let's start with the stackable dairy crates with mostly three sides that stack up on one another. They're great! IF YOU CAN FIND THEM!
Next, again, an Eliot Coleman tip, the bread trays and carts found behind grocery stores and bakery outlets. They're top notched, first rate, professional systems, IF YOU CAN GET THE OWNER TO PART WITH THEM. Hunt them down all over town if you need to as they are well worth the wait, the hunt, the patience and the few bucks to bribe the owner to "depart from this one with the little rust". See photo.
Next comes the hybrid system for innovating farmers and gardeners: The wood sided expanded galvanized metal lathe bottomed tray. See photo. This is a fantastic system for the 'art of soil blocking", which is to air prune all sides for the final elimination of transplant shock. This way is found no where in the plastic pot culture system no matter what they tell you! You can replace the spendy lathe with quail fencing, poly covered fencing, quality gauge hardware cloth, or the new 2'x4' plastic bench tops or lapping animal cage bottoms, found at, cut in thirds and either rimmed with wood or not.
Down the line we now have stackable fiberglass trays used in the food industry or hydroponic systems. Of course, they are the best, but they will cost you a year's worth of home-grown vegetables at your farmer's market. This is a great system for long term investments in soil block equipment used for serious systematic gourmet market growers. They simply last forever and can withstand repeated abuse and harsh climactic conditions.
Fiberglass trays
Now, when it comes to the Micro 20--3/4" (mini-blocker), we use narrow, long wood flats. But, honestly, the home scaled gardener can do so well with reused food containers that would hold a little water, or even complete plastic food boxes with lids and covers, as the Micro 20's must not be allowed to dry out. Micro 20's work better in smooth, flat bottomed trays with a little raised lip for the placement of black plastic strips that seal in heat and moisture, and weight down the seed until it pierces the block dibble and grows the tap root down. See You Tube Video.
The point is, don't get hung up on "where do I put them?", get caught up in good block making and attention to watering needs, and the system will present itself to you according to your environment and conditions. Don't forget to drop us a line if you've found something of interest to all. My promise to the world is to develop a low cost, efficient, excellent expandable system to be used by kitchen gardeners to commerical operations. You'll know it when we find it!  We are the world's resource in soil blockers used for farming.


  1. I love your soil blocking system! This is the first year we are using them and for the trays, luckily my DH like donuts and the ones from our store come in nifty clear clam shell containers, so I saved them and used them for soil blocking to get an extra use out of them before sending them onto recycling. They are working great and what is a good thing about them too is that at first you leave them intact and they work as their own mini greenhouse and you don't have to fret about watering as much, then when time to move onto bigger blocks you can separate them and you have 2 trays! Just thought to share the idea for small gardeners every where.

  2. "soil Blocks are a recently developed seed starting medium used in the United States(earliest records indicate early 70's"


    while looking up 'mid-american growers' the manufacturer of a pot of flowers I got on sale, I came across a family history of horticulturalists, and the term "soil blocking" a term new to me which which when googled led me to you, this family history stated they were soil blocking in perhaps the '30's and perfecting it in the 50's. Link:

    just to let you know.

  3. Hi,
    Nice posting! I am using the micro 20 and am having problems with them drying very quickly. Would you please post or send me a picture of your system. Im not sure what you are using for the strips you mention below.

    "Micro 20's work better in smooth, flat bottomed trays with a little raised lip for the placement of black plastic strips that seal in heat and moisture, and weight down the seed until it pierces the block dibble and grows the tap root down. "

    Thanks so much,
    Adam Hain