How To Use Your Soil Blockers
How To Use Your Soil Blockers
Do we really need to mix our own? (Part 1)
In our professional experience, the answer is an unquestionable "Yes". Allow us to explain. You could very well go to the store and pick up a bag of your normal potting soil. You could wet it down into the "slur" and begin making blocks. However, the results you need, the results you expect from a tool that you've just spent good money on, will be compromised.
You've heard, "your only as good as your weakest link". Potting soil can be your weakest link. Store bought potting soils are never meant to be turned into a bucket of oatmeal. Nor are they capable of withstanding three to one compression. They aren't designed to hold their shape without any container and then be fogged down with water. This is the point where so many people say: "Those soil blockers just don't work very well." They broke the weakest link as their blocks fall apart,and wear away from moisture. Or maybe, they couldn't even get the potting soil to make a block at all.
And, some potting soils are sterilized, so would you still call it "organic"? It can not support a growing plant. We recommend the following ingredients and ratios because they work and have worked on over one million blocks on our farm. This is the fastest way to get excellent results with soil blockers. We have used these exact ingredients with super results.
DO NOT USE COMPOSTED STEER MANURE OR COMPOSTED WOOD BY-PRODUCTS. THEY WILL NOT WORK IN SOIL BLOCKS. THEY WILL INHIBIT GERMINATION DUE TO AMMONIA OFF-GASSING.
Do we really need to mix our own? (Part 2)
The revised answer to this common question is "NO", not anymore. There was a time when mixing your own was the only way. Now, many potting soils have surfaced on the market, many just might work for soil block making. We've tried many. Mixed results, never as good as our own home-made blocking mix.....
However, great results can still be easily had with a little investigation at any nursery, greenhouse, garden center or hardware store.
Just look for a blend of potting soil that has about 3 parts peat to 1-2 parts perlite. This is known as "peat-lite", and is common among growers. Hopefully, the peat has been limed, if not, throw in a handful of dolomite lime. Just blend in 4 parts of that to 3 parts compost, worm castings, or worm compost for a great mix. Leave out the fertilizer, and use a supplemental liquid fertilizer as soon as the plants are 10-14 days old. Pro-Mix brand is one we recommend.
Blocking Soil Mix Recipe (our farm favorite since 2001.)
Use a 10 quart bucket for measuring. A standard mop and bucket is normally 10 quarts. Or, 1/2 of a 5 gallon bucket is 10 quarts or 2.5 gallons. Use a measuring cup for the fertilizer. Use a high-grade very fine to medium fine sphagnum peat moss with environmental quality label on it, like Sunshine Brand.
Note to flower farmers: Leave out the fertilizer meals if you are making blocks in advance and you are not planting seeds immediately, as the breakdown of these meals can interfere with the germination of some flower seeds. Makes 2 bushels (1.6 cubic feet). Mix in an over sized wheel barrow, Vermont Cart, or lay down a tarp and mix by rolling the mix from corner to corner. When mixing by hand, use long sleeved gloves if you don't want dirt under your fingernails. A children's shovel works great.
Follow the directions in the order given. If you can't find the items for the base fertilizer, leave it out and begin fertilizing with an organic liquid fertilizer in 6-10 days after the seeds have sprouted. Flower farmers, leave out the nitrogen fertilizers for your smallest and longest germinating seeds. Try fish emulsions mixed with kelp products. Earth Juice is common. I use organic fertilizers, and common is Maxi Crop and it works great. We have fish fertilizer and liquid kelp of the absolute highest quality if you need it. Make base fertilizer first:
Step 1--Base Fertilizer
Step 2--Blocking Soil
*(If you don't have good garden soil, you can substitute compost for that ingredient. If you don't have good compost, you can substitute pure worm castings or worm compost (vermicompost) for all three parts.)
Mix all ingredients thoroughly. Make sure to blend the lime in with the peat really well. Use a powdered, Horticulture-grade lime over 95% Calcium Carbonate with Magnesium or Dolomite lime. Blending the lime and fertilizer in with the peat first helps distribute it evenly.
Storing mix is just fine as it mellows out the ingredients. And, you'll want to have some around for over watered slurs, so you can "fluff them up". But, don't store the wet mix, or "slur". Use it up, or dry it out and rehydrate again. The wet mix will start to break down, tying up the nitrogen and creating ammonia germination inhibitors.
A different recipe is used for the micro blocker. The idea is to "get 'em up and pot 'em on". No nitrogen meals are used because they are not needed and you'll be "potting on" in a few days anyway. Note: no limestone is needed either. Screen compost and peat moss with a 1/4" mesh screen, first.
Micro Block Soil Recipe (our favorite)
THE LADBROOKE COMPANY RECIPE
Very simple, extremely effective mix. Always mix the peat and limestone first.
Step 3--Make the "Slur"
The slur refers to the wet potting soil. You will want some kind of a durable tub, Rubbermaid bins, wheelbarrows, buckets, etc. work well, but it is really nice to wet down the potting soil and charge your blocker in the same container. Use about 1 gallon of non-chlorinated water to 3 gallons of potting soil. Water down the potting soil and stir with a stick, shovel or your hands. The key here is to get it into an oatmeal-like consistency. You should be able to pick it up, squeeze it tightly and watch the water drip slowly from your hands. You could pick it up and chuck it against a wall, and it should stick for a few moments, then fall. It's sort of like the perfect whipping cream: nice peaks at the top, doesn't fall over when piled, smells sweet and soft to the touch, yet springy and resilient. O.K., got it?! Now, let it sit for one hour.
This is an important step on our farm, and is not taken lightly. I know it's hard to believe, but the one hour will give the peats, whatever they are, time to absorb the water and become completely saturated. This will definitely prevent "dry out", if the blocks are kept moist from here on out. This one hour allows the peat to fill all the dry spots and prevent "wicking" away of moisture by any dry area on a soil block, as they are exposed to air on 5 sides, sometimes 6 sides if you use hardware cloth or mesh bottomed trays to lay your blocks on. You might even notice that the mix seems a little stiffer, a little drier than an hour ago. GOOD! Add a bit more water to make it just right!
Step 4--Charging the Blocker
Get the tub of soil lower than the elbows. I stack one tub on top of a Rubbermaid bin, or for a commercial blocker, leave the bin on the ground. Now, get yourself a bucket of water that will fit a soil blocker. This will dip and clean the blocker before and after each "discharging". The minimal size will do, as you can always replace a smaller amount of water quickly, and not create a mud bath. Dip your soil blocker and then press it firmly on top of and into the blocking mix. Twist left and right, left and right, now pick it off the soil and charge again, deeper, harder, to the bottom floor of your tub. Twisting and pushing.....water should begin oozing out of the top of the blocker, GOOD! It's charged! Pause momentarily and think, "there's a vacuum created at the bottom, and those blocks will stick right to the bottom of that tub if I don't twist and tilt ever so slightly while I lift at the same time!" I used to scrape the bottom clean, but it's not necessary, if you charged that blocker perfectly. However, that will come with some practice, so scrape off the blocker if you like. Now, the thumb and thumb joints are the fulcrum, the pushing off point and the pusher. The fingers hold the blocker steady, steady, place them right where you want them and lay them right on the spot where the blocker was and discharge the blocker while simultaneously lifting the blocker off the tray in a straight vertical non-wavering motion. Say "lift off, straight as an arrow. The blocks should have come out perfect; accept nothing but perfection here, you paid good money to have these little cubes look professional. Keep trying, it's easy, you'll get into it, and you won't be able to stop. Practice a few times, and then throw the cubes back into the bin!
Step 5--Placement of Soil Blocks
One of the most common questions asked is: Where do I put my soil blocks? There are numerous ways to place blocks. We like large sheets of agriculture plastic on heat mats. Also, we reuse anything we can; old 1020 plastic flats, 17 x 17 plastic mesh flats, recycle-able food containers, pieces of plywood, and benches made of mesh screen. The real idea in soil blocks is the Truth presented here: There is no one perfect way, there is only the way that works best for you and your system of gardening or farming. Some have said that with all the adamant advice we have given you, why do you take a hands-off approach to block placement systems? The answer is this: Soil blockers are relatively new in horticulture in America. America has built her entire ag system on cheap imported plastics. To say there is only "one way" is to stop progress in identifying new block placement systems. We are tirelessly looking for ways to improve, but if you are a small farmer the best way is to use the magic of the block and set them on wire benches so that all six sides will be air pruned and ready for field transplants with zero transplant shock. Give them an 1/8" air gap on all sides and mist by overhead misting or fogging or watering deeply with a rose head watering can. Make your own wire mesh trays modeled after opened bottomed plastic flats, but make them any size that fits with your heat mat and bench top space.
Soil blockers work and "do it better!" Our customers will testify to that! Here are a few of the many happy customers that I've heard from.
Thanks, and congrats for your site. It is the best I found about soil block information!!
Chet Marks of South Dakota writes:
I am sending some more photos. The reason is because I have tried every method of seed starting there is out there and my findings don't agree with the "so called" experts. For example I have used Bio Domes from Park seeds, peat pellets(large and small) peat pots, Styrofoam cups, paper pots made with a pot maker, flats and now soil blocks. You can see these methods in the photos. In my opinion as a normal grower I can say that soil blocks are by far the best method. But the experts like Nancy Bubel in her book "THE NEW SEED-STARTERS HANDBOOK" in chapter 4 on containers says about soil blocks, and I quote " In my experiments with blocks, I found that they do indeed promote good root growth. For me though,they had two disadvantages. The first was the time and trouble necessary to make the blocks. Secondly, the blocks must be very carefully and frequently watered from above so they don't disintegrate." end of quote. I don't believe any disadvantages exist that outweigh the advantages. Maybe we should stop listening to the experts and be willing to try methods that have a history of effectiveness. Just because someone wrote a book don't mean that they are right about everything. I realize she expressed it as her experience but people I think take that and figure her experience will be theirs and don't try soil blocks. I can say that having tried all methods; soil blocks are by far the best way. Photos attached are of the different seed starting tools I mentioned. For those who are reluctant to try soil blocks tell them I said they will be glad they did. "JUST DO IT" as NIKE says. Thank you for the season cycles, we are using those to help us keep track. I look forward to a great growing season. It gives a whole new meaning to having a block party.
Dee Ann of Ohio writes:
Soil blocks are so much better than small mesh peat pots. I purchased the 2 inch block maker and had so much fun with that my husband made me a hydraulic 4 inch block maker that I used for the big seeds. Just to let you know that we were enjoying cucumbers, zucchini and summer squash before the forth of July. The mammoth sunflower was over eight foot. Some of my pumpkins are the size of basketballs. And we should have sweet corn by next week. (July 12)
Gail from North Florida writes:
I cannot describe my joy upon finding your site! I last used soil blocks in 1984. Then I wasn't able to really contemplate gardening for a long (too long) time. Now I'm in North Central Florida, have undertaken to begin a garden, and went hunting for soil block makers, which were the most successful means I've ever used for starting all types of seeds. Lo and behold, yours was the first one to pop up, and it was with sheer delight that I began reading all the information. It took me back 24 years and many happy memories. I have, of course, ordered my soil block makers [from PottingBlocks.com] and can hardly wait until they arrive so that I can begin to garden once again. Thank you for a wonderful web site and for all the information you make available. I can now pursue a long-deferred dream.
Sharon of Ontario writes:
Love your site and appreciate the loads of info. Just started CSA this spring in Ontario about 3 hrs east of Toronto, with the soil block method. At times, felt like sending hate mail to Elliot Coleman, but found your site and have been lovin’ it ever since. So simple, and so sensible!
Charles L Shreffler of New York writes:
I received your soil blockers (micro 20 and mini 4) Friday Oct 7 2011, I was eager to try them out so I mixed up some potting soil I had and started practicing. They came out pretty good so I just sat them in the green trays you sent me. Then I proceeded to plant some lettuce and kale seeds misted them down and put the humidity cover on them.
That was Friday afternoon, I was really surprised when I checked them Saturday afternoon some seeds had already sprouted. Now on Monday this is what they look like.
I am really pleased with the results.
From an email dated 1/3/11
I received my mini-4 and OFB mix today, and had made and planted thirty blocks of lettuce inside of an hour, including 45 minutes for the mix to soak. I find the Ladbrooke unit to be extraordinarily easy to use; having never made a block in my life, but having seen your instructional video, I have yet to have any difficulty producing many blocks with speed! Following your "oatmeal" consistency rule, and soaking for 30-45 minutes in advance, I have yet to have a block fail! In fact, believe it or not, my four year old made eight blocks himself with only my assistance with pressing hard enough to charge on the second push. If he can do it without practicing, I have no doubt that even a complete gardening amateur could pick it up and start out with 100% success! I even got the mix wrong initially, but the Ladbrooke overcame my over-watering and squeezed out the excess when charging the block. It seems that if you have the right soil mix (your Old Farm Boy works flawlessly) and the Ladbrooke unit, you can't really go wrong.
From an email dated 10/25/2010
I'm thrilled with my blockers and anxious to get started. Thank you for your promptness, great website and the free coco peat and dowel pins. . . Thank you for helping me be successful in my huge 1/2 acre farm!
Tami Greever, Arkansas
From an email dated 11/15/09
Subject: "Superb Service"
I recently ordered a number of soil blockers from you. I have received them all and I can't wait to use them. They all arrived before I expected them. Thank you ever so much for the emails informing me of shipping dates. I would not hesitate to recommend you to anyone, and the next time I need soil blockers I will definitely order through you.
Thanks again from a VERY satisfied customer!!
David Vigue, California
What are Potting Blocks?
Potting Blocks, also known as soil blocks, are free-standing compressed cubes of potting soil which hold their shape without any container. Potting Blocks are made from a zinc coated stainless steel Soil Block Maker, much like an ejection mold. The block maker metal form is packed into a tub of pre-moistened potting soil and then discharged into nice, firm, blocks with a pre-drilled seed or transplant holes formed right into the top. Potting Blocks are used for seed starting or germination, and transplanting. They have an amazing success rate due to the volume of soil compressed in the cube. The roots are naturally "air pruned" due to the air barrier of the "container-less" cube. They become the growing medium and the container! They are used for everything; herbs, flowers, vegetables, cuttings, and other transplants.
Potting Blocks have many advantages over traditional potting methods. First, they eliminate transplant shock! The seedling and root system stays intact and protected, a "home away from home". They will not become "'root-bound". They eliminate root circling. They replace plastic pots, trays, inserts,etc. They contain more cubic volume of soil than pots of the same top dimensions. They promote great air circulation. They have a major increase in space utilization than round pots. And, studies in Europe have shown that Potting Block transplants are superior in performance than container-bound transplants.
Where did they come from?
(Read more about the "Living History of Soil Blocks".)
Soil blocks have been used in Mexico for over 2000 years! Has anyone ever heard of the "Floating Gardens" of Mexico City? Well, about the same time Christ was born, a small band of poor,semi-barbaric tribe of Aztecs in central Mexico were trying to find a settlement safe from other warring tribes. This tribe was know as the Xochimilcos (pronounced so-chi-mil-cos). They were inhabitants of the Central Valley of Mexico, a huge valley completely surrounded by volcanic mountains. After fighting with neighboring tribes, they decided to retreat to some islands on the shallow lakes of present day Mexico City, which have long since been drained. These lakes were caused by constant flooding of mountain runoff from rain and springs. There, on these
islands, in a land locked basin, they had to create a system of land reclamation. This land reclamation and subsequent agriculture is know as the Chinampas system. Chinampas farming is the most intensive and productive methods of farming that has ever been devised! It provided the Aztecs with land to live on and their first surplus of food they have ever known. This new wealth enabled them to quickly build standing armies and soon conquer all of Central Mexico, supported completely by Chinampas farming.
Misinterpreted as the "Floating Gardens", Chinampas are actually long narrow strips of land surrounded by water, like a peninsula. These strips of land were separated by drainage canals. From the depths of these canals, the peaty sediment and mountain runoff were scooped up and piled on top of the land strips, making them higher than the flooding waters. They would weave branches and live willow trees to anchor the rich, mucky soil in place. This created a moist planting surface. Every year another layer of fertile mud would be dug up and spread on top of the existing chinampa.
The most essential element in chinampas farming is the seedling nursery technique. Here, the original soil blocks were created. At one end of the peninsula, the thick mud was spread over a wattle of weeds. After several days the muck would be hard dry enough to cut into little rectangular blocks called chapines. Then, the chinampero, or farmer, makes a little hole with his finger or a stick in each chapine, drops the seed in the hole and covers with a little manure. They were watered in the dry season and covered with reeds in the winter to protect from frosts. The seedling is then transplanted in the chinampa, which was leveled and hoed using a digging stick, or coa. Finally, it was covered with a thick layer of fertile canal mud. The Xochimilcos raised corn, beans, chili peppers, tomatoes, and amaranth. Flowers were also grown with this method. A dozen varieties of dahlias, and marigolds were grown for the altars of the pagan gods. Later, after the Spanish conquered the Aztecs, they continued to grow the native varieties and European crops like, carrots, lettuce, cabbage, beets, radishes, onions, carnations, roses, and lilies. See Real Pictures of Modern Day Chinampas.
Most recently developed in Holland, the potting blocker, is now made of a zinc coated prefabricated steel. They have been in use there for about 100 years. The Dutch are the oldest known users of ‘perspotten’ (soil blocks) in Europe and have used them since the late 1890's. Europeans have been using potting blockers for market gardening for decades. According to the Museum of Gardening at Harlow Carr London, UK, "Before 1939 large numbers of plants were raised annually in clay pots. These commonplace earthenware items required considerable fuel to fire them, and production ceased during the war. The solution was to make the growing medium self supporting. The moving parts of the soil block maker shown here are a hexagonal mould and a compacter with a hexagonal base and a bullet shaped centre. Each part slides on a pair of vertical rails and can be retained at the top with a spring clip. In use, the mould is loosely filled with compost, the compacter is brought firmly down with two hands, and finally mould and compacter are raised together. The block is then slid out. The compacter leaves a central depression which is filled with a pinch of loose compost, and in this the seed is sown." "The blocks are 7cm across, and the hexagonal shape allows close-packing on glasshouse bench or floor. A plate on top of the device is engraved the Goradam easy-one soil block maker."
The Ladbrooke Soil Blocker is the best made blocker on the market today. It comes in many sizes from small home gardener sizes to large stand up blockers for the commercial farmer. (See our soil blocker size chart.) Soil blockers have only been used, rarely, since the 1950's here in the U.S.A, and mostly from immigrants from the Netherlands trying to escape German occupation. The soil block transplants were wrapped in tin foil and sold by the dozen as flower or vegetable starts. They are increasing in popularity though, as high oil prices for plastics and environmental responsibility takes center stage.
What are the disadvantages?
The soil block gardening method needs attention. Although this may not be seen as a disadvantage to some, others may find it new to their gardening style. It is precisely why the soil blocks work so well, that they need extra attention paid to their needs. Rapid growth in the block requires constant monitoring of the watering. And, if growth is to be expected, than so does the proper timing of the "potting on" or transplanting. It is a horticulture fact that plants grow the fastest when they are given just a little more room to grow than their previous space. This requires precise timing as to when to transplant. Daily routines must be established to check for warmth, light, growth, water and weather. The very nature of soil block gardening means starting earlier in the spring or late winter. Paying close attention to weather to watch for "windows of opportunity" are part of the game of transplanting.
And, to some, the biggest disadvantage is the cost of the system startup. The block makers from Ladbrooke don't come cheap. At the same time, they are made by British engineers with the highest standards. They simply work year after year with no malfunctions. Some, have reported the cost of soil blockers to be prohibitive, and outweigh the benefits produced. Let's look at that. You can easily spend a few hundred dollars on equipment your first year. (But, you can invest in the micro 20 for your first year for under $30.00.) The "basic three", Micro 20 (3/4"), Mini 4 (2"), and the Maxi 1 (4"), will get you a maximum of 10,000 plants in one year without upgrading to commercial units. You will keep the same equipment for decades. You will no longer be purchasing plastic, which is always rising in price. You will no longer be cleaning pots and trays. You also don't need to have so much storage for pots. And, for fans of the Rockwool System, blocks can do the same thing, for only the cost of the potting soil, not the individual block.
We can say for certain, potting blocks are an investment that pay dividends your first year, completely pay for themselves in a couple of months, rise in value daily, while lasting for years and years. For myself, there are no disadvantages. When I set out to farm on my own, I started with soil blocks and soil block makers from the beginning. I learned the hard way: trial and error. But, I also proved the system worked and I worked to do it right and better. You all are enjoying the benefits of a decade of serious soil block experiments.
Just because you're on the right track doesn't mean you can just sit there.
How does a soil blocker work?
(See our How-to Pictorial.)
A soil blocker makes little compressed cubes of free standing potting soil. First, a large tub is filled about one-third of the way with the appropriate type of potting soil, know as the "blocking mix". It is moistened to the consistency of wet oatmeal, known as the "slur". Stirred well, it is left to soak up all the water for about one to three hours. This ensures that all the fibers in the mix are moist enough to bind or "knit" together, and the consistency holds the block upright. This is very different from using traditional dry filled plastic containers! You should be able to pick up a handful of slur and squeeze out a few drops of water. Then, it is perfect. Mound up the slur in the center, like a little hill. Now, one comes up to the tub with a blocker in two hands (or one hand with the smallest blocker) and, making sure the mound is three times the height of the blocker being used. Diving straight in and parallel to the ground the blocker is thrust in the mud and twisted back and forth. When the blocker hits the bottom of the tub, tilt back slightly to release the suction from the bottom and twist all at the same time and do it again. By the second or third thrust you should see some water oozing out the top. This is known as "charging" the block. You can't over pack the blocker. Once it is compacted, it must be "discharged". There is a spring loaded lever that is lifted against the handle when the blocker is placed where you want to release the blocks. Lift up the handle while pressing the lever and the blocks come sliding out, effortlessly! You can set them on pieces of wood, other plastic trays, a piece of plastic, or some hand made wooden crates, which we'll describe later. There sits a perfectly square molded soil block complete with an indented seed hole. They are strong, sturdy, a pot without any sides. Pick them up and move them around. Simply brilliant!
Why are they so great?
Less space, more soil, no pots, better growth.......
Scientific studies* have shown soil blocks to perform much better when transplanted than traditional methods like plastic pots, plugs, peat pots, compressed peat pots, or the Japanese paper pot. And, they sure are a lot cheaper than rockwool cubes! Researchers have also proved that plant roots grow better in cubes rather than tapered pyramid plugs*. It's all about the transplanting, and plants grown in soil blocks never know they aren't already growing where they're supposed to live! Why? The walls of the potting block are actually the air that surrounds it. So, when the root gets close to the air it turns backward and focuses it's growth in the center of the cube. This eliminates transplant shock! Plastic pots, on the other hand, encourage root circling and root rot; giving the plant a false impression of life!
Transplanting into garden soil will shock the plant and they tend to wilt and become stunted. But the blocks remain ready for explosive growth as the roots move out of the block into the garden soil at it's own pace, adjusting to the new air to moisture ratio. And, they're much sturdier than other transplants. The root ball is heavy and concentrated in the center of the block, so it is less likely to be affected by wind. It can also be handled easier. Pick it up and toss it to your neighbor. You'll shock them, not the plant! They don't fall apart. You aren't hacking away at their roots to get them out of the pot, you're not "pricking" them out of tightly knit flats with intertwined roots. Roots are their water and nutrient uptake system. You'll feel a lot better if you don't see roots!
The investment in potting blockers pays dividends immediately, and they free up so much extra time by eliminating the cleanup and sterilization process of plastic pots and plugs. There is also no more purchasing of plastic pots, trays, plugs, plugging machines, peat pots, etc. It beats the constant price hike in petroleum by-products! And, best of all, for large-scale growers, it eliminates the huge mounds of broken and deteriorated plastic pots and trays. This makes it an excellent environmental product to use. There are no breakable parts and they last for decades without any maintenance. Just keep them clean with a little rinse off so the organic acids in the soil mixes won't corrodes the metal.
This will ensure trouble-free use. Blockers are also highly regarded in Organic farming as the standard for quality. Potting blocks are also an efficient use of space. Potting blocks allow more plants per square foot of space than any round pot. And they won't get knocked over. You can build custom wooden trays that allow you to stack trays of blocks on top of each other. Because of it's cubic, rather than tapered sides, potting blocks contain 2-3 times as much volume of soil than a plastic pot of the same top dimension. For example, the 4" Maxi blocker has the same volume of soil as a 6" plastic pot, and can hold a transplant for up to 8 weeks!
*W.J.C. Lawrence, Catch the Tide: Adventures in Horticultural Research (London: Grower Books, 1980),pp.73-74
What about Peat pots? Aren't they biodegradable?
Many people use peat pots. They are supposed to be biodegradable. The pot and all are set into the garden. They are bound together with a lot of glue which inhibits roots growth and penetration. They often won't let all the roots out and you're left with a piece of trash in your garden. Or, the ones with less glue will fall apart before it even reaches the garden. Or, they'll drown in a pool of water because the pot doesn't drain properly. We've never had great results with them, anyways. The compressed pellets that expand open when water is added, are almost more trouble. They have already lost their water holding capacity thanks to the manufacturing process of wetting and dehydrating and compacting. And, at the end of the year your garden is filled with little, messy plastic nettings which do not breakdown!
How do you seed them?
The potting blocker makes it's own seed hole, or transplanting hole. This is a huge difference. Uniform, consistent, reliable, accurate holes are placed or indented on the top of the cube for you. This saves time and hassle of making it yourself (like our Aztec friends had to do). The potting blockers also come in a variety of seed hole makers know as "pins". The "seed pin" is the smallest and works well with small to medium size seeds. The "dowel pin" is deeper and works great for large seeds or cuttings. The "cubic pin" is 3/4" x 3/4" and indents a perfect little cube for potting the micro blocks (3/4") onto larger 2" blocks. The cubic pin also works great for huge seeds, or multiple seeds in one block. With all the different sizes, many seeds are sown in blocks that one normally doesn't associate with transplanting, like corn, peas, and beans.
You seed them with precision seeders, or by creasing a seed packet and tapping seeds in one at a time to prevent duplicates. You can use a wetted pencil, bamboo chop sticks, and toothpicks by wetting and touching the seed and then touching the soil block. It will stick because the soil is stickier than the seed held by water on the pencil.
What kind of potting soil should I use?
The soil in which blocks grow must be specially formulated or at least specifically blended. This medium is known as "Blocking Mix", or "Blocking Soil". While there may be many commercial varieties of potting soil available, mixing your own makes the very best. The reason being is that most potting soils do not contain real "soil". Good garden soil from your own carefully tended plot is a key component to the overall health of your transplants. Here, in your soil, lies secret ingredients: bacteria, fungi, nematodes, protozoa, beneficial micro-organisms, are known as the "good guys" and are actually protecting your garden from the 1% "bad guys".
Much like the Chinampas of Mexico, your blocks should be made from some of your own soil. But, blocking soil also needs extra fiber, like peat moss, coir fiber or peat plus coco peat, to ensure it won't fall apart when watered to a sticky paste, or slur. Peats add great water holding capabilities, since blocks have no pot to sit in and drink freely. Blocks also require good air porosity and drainage. This is where Perlite, asbestos-free vermiculite, and sand come to play. And, of course, compost. Blocks need compost, countless books being written on the stuff. The miracle maker, the fertility factory, the nutrient warehouse, compost. Good compost is well decomposed, and preferably comes from your own pile. We will get into good compost soon.
And finally, the icing on the cake is rock dust. There's limestone, the most important, if peat moss is used. Limestone sweetens the peat so it's not overly acidic. There are other rock powders, like colloidal phosphate, also known as soft rock phosphate. Glacial rock dust, from old glacial moraines, contain over 70 trace minerals. They give the transplants a "salad bar" option for nutritional requirements. Greensand, another mineral deposit from the ocean floor, is also used for it's trace mineral content. You can also add a slow release fertilizer, like blood meal, feather meal, cotton seed meal, shrimp or crab shell meal, or alfalfa meal. You must use only slow release nitrogen meals to germinate seeds successfully. Slow releasing nitrogen meals will not affect seed germination, because after the seed has germinated and used up it's own reserves, then the nitro meals will begin to break down into soluble food for the roots.
What kind of peat do I use?
Peat is partially decomposed plant residue from bogs and swamps. Peat is the planting medium of choice for most growers. It's lightweight, weed and disease-free, and holds 7-30 times it's dry weight in water while still providing air spaces. Peat contains valuable organic acids, which increase microbial action, which, in turn, releases nutrients for plant roots. But, peat is variable, and comes in many colors and lengths, and there are also many commercial varieties to choose from. There's black peat, from the bottom of swamps, white peat from the tops of bogs, and brown peat, from somewhere in the middle, peat from Wisconsin, Montana, Germany, Scandanavia, and Canada. Canadian peat is the most common, most popular, cheapest, and most plentiful, with the best qualities for the price. The best for potting blocks is sphagnum peat moss; milled and screened, medium fiber length, and medium brown in color. Be sure to find a peat moss without any wetting agents, additives, sticks or dust. It's worth the extra effort to find the best. Just make sure to have a 1/4" hardware screen handy in case a good peat needs further screening of longer fibers or a few sticks. We use Sunshine Peat Moss under the Sun-Gro label. Here, in the Northwest, this is the very best! Growers in the Midwest and the East can drop us a line and let us know the best out there.
The environmentally friendly alternative, Coco Peat is made from coconut husks left over after the coconut meat and milk have been taken. Coco Peat is an amazing alternative for those individuals who are worried about the environmental impact of peat bog harvesting. And, surprisingly, it works just as well, and maybe better! Coco peat can last three times longer than peat, giving you more organic matter in your soil for a longer time. It is disease resistant! And, it is superior in nutrient and water storage abilities. It holds 8-9 times its weight in water and comes with a balanced Ph of 5.7-6.8. Coco peat has been thoroughly tested and approved for Organic Agriculture. Coco Peat is hard to beat! We have used it extensively in potting block production, and really enjoy working with it. You must mix it half and half with your peat, as it can not knit together on it's own. It smells so wonderful, you could eat it! As it's popularity grows, so does the companies competing for your dollars. Always buy coco peat that is washed of excess salts, as coconuts absorb salt from the ocean water. Check for a balanced Ph, too. Coco peat comes in compressed bales or bricks. They will fluff up to 4-5 times their size. You can fluff it up by soaking it in warm water for an hour or two.
When using a balanced Coco peat, the limestone is omitted. Adding a little oyster shell does season it just right, though. Coco peat should be mixed with peat moss, though. Use about half and half. A final clarification needs to be made about coir fiber, also known as coir pith, or coconut fiber is not the same as coco peat. Coir fiber is longer, shredded made from the coconut pithy waste, and is a separate by-product of the coconut meat industry; whereas coco peat is the crushed, milled and screened coconut hull. Also, the best coconut fiber is composted and aged for 1-2 years, and is washed free of salt and ph balanced and also used in hydroponics. This is the only coconut product able to "knit" together to make perfect soil blocks. It's what we now use in our Old Farm Boy blocking mixes.
(Note: We give you the maximum coco peat ratio for stable blocks(50/50), but our farm uses 1/3 coco pith to 2/3 peat moss.)
Homemade mixes aside, there are commercially available potting soils that work just fine. We have used Pro-Mix quite successfully. We also sell our own private label potting soil known as Old Farm Boy (you know it's the best!). Others may be available, so try them all out if you don't want to mix your own. If you're an Organic grower, make sure to check the ingredients and compare with OMRI (Organic Material Review Institute), there are companies out there that claim to be "organic", but actually contain non-organic materials.
Environmental Note: Always buy peat moss from companies that have the label "Canadian Sphagnum Peat Moss Association". They are committed to the ecological harvesting of peat bogs that replenish themselves faster than they can harvest the peat.
I quote Eliot Coleman from "The New Organic Grower":
"Of the peat lands in North America, only 0.02 percent (2/100 of 1 percent) are being used for peat harvesting. On this continent peat is forming some five to ten times faster than the rate at which we are using it. And even if we don't include bogs located so far north that their use would never be economic, peat is still a resource that is forming much faster than we are using it. To my mind that is the definition of renewable resource."