Ditch the Pots, Use Soil Blocks!

What’s a less expensive, simpler, and surprisingly extra environment friendly method to begin your seedlings? Soil blocks!

For those who’ve by no means used them earlier than, learn on to learn how soil blocks work, the way you make them, and what benefits they provide over conventional pots and trays.

The next is an excerpt from The New Natural Grower by Eliot Coleman. It has been tailored for the online.

How Soil Blocks Work

A soil block is just about what the title implies—a block made out of evenly compressed potting soil. It serves as each the container and the rising medium for a transplant seedling. The blocks are composed completely of potting soil and don’t have any partitions as such. As a result of they’re pressed out by a kind reasonably than stuffed into a kind, air areas present the partitions. As an alternative of the roots circling as they do upon reaching the wall of a container, they fill the block to the sides and wait. The air areas between the blocks and the slight wall glazing brought on by the block kind preserve the roots from rising from one block to a different. The sting roots stay poised for fast outward progress. When transplanted to the sphere, the seedling shortly turns into established. If the crops are saved too lengthy within the blocks, nevertheless, the roots do lengthen into neighboring blocks, so the crops needs to be transplanted earlier than this occurs.

Regardless of being not more than a dice of rising medium, a soil block shouldn’t be fragile. When first made, it’s certain collectively by the fibrous nature of the moist substances. As soon as seeded, the roots of the younger plant shortly fill the block and guarantee its stability even when dealt with roughly. Soil blocks are the reply for a farm-produced seedling system that prices not more than the “soil” of which it’s composed.


The perfect factor concerning the soil-block system is that every little thing that may be achieved in small pots, “paks,” trays, or plugs might be achieved in blocks with out the expense and hassle of a container. Blocks might be made to accommodate any want. The block could have a small melancholy on the highest wherein a seed is planted, however blocks can be made with a deep middle gap wherein to root cuttings. They can be made with a big gap wherein to transplant seedlings. Or they are often made with a gap exactly the scale of a smaller block, so seedlings began in a germination chamber in small blocks might be shortly transplanted onto bigger blocks.

Blocks present the modular benefits of plug trays with out the issues and expense of a plug system. Blocks free the grower from the mountains of plastic containers which have develop into so ubiquitous of late in horticultural operations. European growers promote bedding crops in blocks to prospects, who transport them in their very own containers. There isn’t any plastic pot expense to the grower, the shopper, or the setting. In brief, soil blocks represent the most effective system I’ve but discovered for rising seedlings.

Skilled hand soil-block makers for various sizes of blocks.

The Soil-Block Maker

The important thing to this method is the device for making soil blocks—the soil-block maker or “blocker.” Principally, it’s an ejection mould that types self-contained cubes out of a rising medium. Each hand and machine fashions can be found. For small-scale manufacturing, hand-operated fashions are completely enough. Motorized block-making machines have a capability of over 10,000 blocks per hour. However they’re manner overscaled for a 5-acre vegetable farm.

There are two options to grasp concerning the blocker in an effort to recognize the flexibility of soil blocks: the scale of the block kind and the scale and form of the middle pin.

The Type

Varieties can be found to make ¾-inch blocks (the mini-blocker), 1½-inch blocks, 2-inch blocks, 3-inch blocks, and 4-inch blocks (the maxi-blocker). The block form is cubic reasonably than tapered. Horticultural researchers have discovered a cubic form to be superior to the tapered-plug form for the basis progress of seedlings.

Two components affect selection of block measurement—the kind of plant and the size of the supposed rising interval previous to transplanting. For instance, a bigger block could be used for early sowings or the place planting outdoors is prone to be delayed. A smaller block would suffice for short-duration propagation in summer season and fall. The mini-block is used solely as a germination block for beginning seedlings.

Clearly, the smaller the block, the much less potting combine and greenhouse house is required (a 1½-inch block comprises lower than half the amount of a 2-inch block). However, in selecting between block sizes, the bigger of the 2 is often the safer selection. After all, if a smaller measurement block is used, the crops can all the time be held for a shorter time. Or, as is widespread in European business blocking operations, the nutrient necessities of crops in blocks too small to take care of them might be supplemented with soluble vitamins. The necessity for such supplementary fertilization is an absolute requirement in plug-type programs, as a result of every cell comprises a lot much less soil than a block. The favored upside-down pyramid form, for instance, comprises solely one-third the soil quantity of a cubic block of the identical prime dimension.

My choice is all the time for the bigger block, first as a result of I imagine it’s false financial system to stint on the care of younger crops. Their vigorous early progress is the inspiration for later productiveness. Second, I want to not depend on soluble feeding when the overall nutrient bundle might be enclosed within the block from the beginning. All that’s obligatory when utilizing the fitting measurement block and soil combine is to water the seedlings.

One other issue justifying any additional quantity of rising medium is the addition of natural matter to the soil. If lettuce is grown in 2-inch blocks and set out at a spacing of 12 by 12 inches, the quantity of natural materials within the blocks is the equal of making use of 5 tons of compost per acre! Since peat is greater than twice as priceless as manure for growing long-term natural matter within the soil, the blocks are literally price double their weight in manure. The place succession crops are grown, the soil-improving materials added from transplanting alone might be substantial.

The Pin

The pin is the thing mounted within the middle of the highest press-form plate. The usual seed pin is a small button that makes an indentation for the seed within the prime of the soil block. This pin is appropriate for crops with seeds the scale of lettuce, cabbage, onion, or tomato. Different pin varieties are dowel- or cube-shaped. I take advantage of the cubic pin for melon, squash, corn, peas, beans, and every other seeds of these dimensions. An extended dowel pin is used to make a deeper gap into which cuttings might be inserted. Cubic pins are additionally used so a seedling in a smaller block might be potted on to a bigger block; the pin makes a cubic gap within the prime of the block into which the smaller block is positioned. The several types of pins are simply interchangeable.

Blocking Techniques

The ¾-inch block made with the mini-blocker is used for beginning seeds. With this small block, huge portions of modular seedlings might be germinated on a heating pad or in a germination chamber. That is particularly helpful for seeds that take a very long time to germinate, as a result of a minimal of house is used within the course of.

Mini-blocks are efficient as a result of they are often dealt with as quickly as you wish to pot on the seedlings. The oft-repeated admonition to attend till the primary true leaves seem earlier than transplanting is improper. Particular investigations by W.J.C. Lawrence, one of many early potting-soil researchers, have proven that the earlier younger seedlings are potted on, the higher is their eventual progress.

The 1½-inch block is used for short-duration transplants of ordinary crops (lettuce, brassicas) and because the seed block for cucumbers, melons, and artichokes through the use of the big seed pin. When fitted with a protracted dowel pin it makes a wonderful block for rooting cuttings.

The two-inch block is the usual for longer-duration transplants. When fitted with the ¾-inch cubic pin, it’s used for germinating bean, pea, corn, or squash seeds and for the preliminary potting on of crops began in mini-blocks.

The three-inch block fitted with a ¾-inch cubic pin presents the choice to germinate many various discipline crops (squash, corn, cucumber, melon) when greenhouse house shouldn’t be important. Additionally it is a perfect measurement for potting on asparagus seedlings began in mini-blocks.

The 4-inch block fitted with a 1½- or 2-inch cubic pin is the ultimate house of artichoke, eggplant, pepper, and tomato seedlings. Due to its cubic form, it has the identical soil quantity as a 6-inch pot and might develop distinctive crops of those crops to their five- to eight-week discipline transplant age.

Different Pin Choices

Along with the pins provided with the blocker, the grower could make a pin of any desired measurement or form. Most onerous supplies (wooden, steel, or plastic) are appropriate, so long as the pins have a clean floor. Plug trays can be utilized as molds and stuffed with quick-hardening water putty to make many various sizes of pins that permit the mixing of the plug and block programs.

Blocking Mixes

When transplants are grown, whether or not in blocks or pots, their rooting space is restricted. Subsequently the soil wherein they develop should be specifically formulated to compensate for these restricted situations. For soil blocks, this particular rising medium is a blocking combine. The composition of a blocking combine differs from an abnormal potting soil due to the distinctive necessities of block-making. A blocking combine wants an additional fibrous materials to resist being watered to a paste consistency after which shaped into blocks. Unmodified backyard soil handled this fashion would develop into onerous and impenetrable. A blocking combine additionally wants good water-holding skill, as a result of the blocks should not enclosed by a nonporous container. The majority substances for blocking mixes are peat, sand, soil, and compost. Retailer-bought mixes also can work, however most will comprise chemical components not allowed by many natural certification packages. If you could find a business peat-pearlite combine with no components, you possibly can complement it with the soil, compost, and further substances described under.

Up to now few years business, preformulated natural mixes with fairly goof progress potential have begun to look available on the market. Nonetheless, delivery prices might be costly if you happen to reside far-off from the provider. To be trustworthy, I’ve but to search out any of those merchandise that can develop as good seedlings as my very own housemade mixes.


Peat is a partly decayed, moisture-absorbing plant residue present in bogs and swamps. It supplies fiber and further natural matter in a combination. All peats should not created equal, nevertheless, and high quality can fluctuate vastly. I like to recommend utilizing the premium grade. Poor-quality peat comprises a variety of sticks and could be very dusty. The higher-quality peats have extra fiber and construction. Maintain asking and looking out your native backyard suppliers till you could find good-quality peat moss. Fairly often a big greenhouse operation that makes its personal combine can have entry to an excellent product. The peat offers “physique” to a block.


Sand or some comparable granular substance is beneficial to “open up” the combo and supply extra air porosity. A rough sand with particles having a 1/8 to 1/16 inch diameter is the simplest. I want to not use vermiculite, as many business mixes do, as a result of it’s too mild and tends to be crushed within the block-making course of. If I need a lighter-weight combine I exchange the sand with coarse perlite. Regardless of the coarse product concerned, enough aeration is essential to profitable plant progress in any medium.

Compost and Soil

Though most trendy mediums not embody any actual soil, I’ve discovered each soil and compost to be vital for plant progress in a combination. Collectively they exchange the “loam” of the profitable old-time potting mixtures. Together with the opposite substances, they supply steady, sustained-release diet to the crops. I think essentially the most priceless contribution of the soil could also be to reasonable any extra vitamins within the compost, thus giving extra constant outcomes. Regardless of the motive, with soil and compost included there is no such thing as a want for supplemental feeding.

Compost is crucial ingredient. It’s best taken from two-year-old heaps which can be high quality in texture and effectively decomposed. The compost heap should be fastidiously ready for future use in potting soil. I take advantage of no animal manure within the potting-mix compost. I assemble the heap with 2- to 6-inch layer of combined backyard waste (e.g. outer leaves, pea vines, weeds) lined with a sprinkling of topsoil and a couple of to three inches of straw sprinkled with montmorillionite clay. The sequence is repeated till the heap is full. The heap needs to be turned as soon as the temperature rises and begins to say no in order to stimulate additional decomposition.

Soil blocks develop nice root programs with no circling.

There are not any worms concerned in our composting besides these naturally current, which is often a substantial quantity. (I’ve bought business worm composts [castings] as a trial ingredient, and so they did make an enough substitute for our compost.) Each through the breakdown and afterwards the heap needs to be lined with a panorama material. I strongly counsel letting the compost sit for a further yr (in order that it’s one and a half to 2 years previous earlier than use); the ensuing compost is effectively well worth the hassle. The higher the compost ingredient, the higher the expansion of the crops will probably be. The distinctive high quality of the seedlings grown on this combine is motive sufficient to take particular care when making a compost. Compost for blocking mixes should be stockpiled the autumn earlier than and saved the place it gained’t freeze. Its worth as a combination ingredient appears to be enhanced by mellowing in storage over the winter.

Soil refers to a fertile backyard soil that can be stockpiled forward of time. I gather it within the fall from land off which onions have simply been harvested. I’ve discovered that seedlings (onions included) appear to develop greatest when the soil within the blocking combine has grown onions. I think there may be some organic impact at work right here, since crop-rotation research have discovered onion (and leeks) to be extremely useful previous crops in a vegetable rotation. The soil and compost needs to be sifted by way of a ½-inch mesh display screen to take away sticks, stones, and lumps. The compost and peat for the extra-fine combine used both for mini-block or for the propagation of tiny flower seeds are sifted by way of a ¼-inch mesh.

Additional Components

Lime, blood meal, colloidal phosphate, and greensand are added in smaller portions.

Lime. Floor limestone is added to regulate the pH of the blocking combine. The amount of lime is decided by the quantity of peat, essentially the most acidic ingredient. The pH of compost or backyard soil shouldn’t want modification. My expertise, in addition to latest analysis outcomes, has led me to purpose for a rising medium pH between 6 and 6.5 for all the main transplant crops. These growers utilizing totally different peats within the combine could wish to run a number of pH assessments to make certain. Nonetheless, the amount of lime given within the formulation under works for the totally different peats that I’ve encountered.

Blood Meal. I discover this to be essentially the most constantly reliable slow-release supply of nitrogen for rising mediums. English gardening books typically confer with hoof-and-horn meal, which has similarities. I’ve additionally used crab-shell meal with nice success. Current impartial analysis confirms my expertise and means that cottonseed meal and dried whey sludge additionally work effectively.

Colloidal Phosphate. A clay materials related to phosphate rock deposits and containing 22 p.c P2O5. The finer the particles the higher.

Greensand (Glauconite). Greensand comprises some potassium however is used right here principally as a broad-spectrum supply of micronutrients. A dried seaweed product like kelp meal can serve the identical goal, however I’ve achieved extra constant outcomes with greensand.

The final three supplementary substances—blood meal, colloidal phosphate and greensand—when combined collectively in equal components are known as the “base fertilizer.”

Blocking Combine Recipe

A typical 10-quart bucket is the unit of measurement for the majority substances. A typical cup measure is used for the supplementary substances. This recipe makes roughly 2 bushels of combine. Comply with the steps within the order given.

  • 3 buckets brown peat
  • ½ cup lime. Combine.
  • 2 buckets coarse sand or perlite
  • 3 cups base fertilizer. Combine.
  • 1 bucket soil
  • 2 buckets compost

Combine all substances collectively completely.

The lime is mixed with the peat as a result of that’s the most acidic ingredient. Then the sand or perlite is added. The bottom fertilizer is combined in subsequent. By incorporating the dry supplemental substances with the peat on this method, they are going to be distributed as uniformly as attainable all through the medium. Subsequent add the soil and compost, and blend utterly a closing time.

Mini-Block Recipe

A distinct mix is used for germinating seeds in mini-blocks. Seeds germinate higher in a “low-octant” combine, with none blood meal added. The peat and compost are finely screened by way of a ¼ inch mesh earlier than including them to the combo.

  • 4 gallons brown peat
  • 1 cup colloidal phosphate
  • 1 cup greensand (If greensand is unavailable,
  • go away it out. Don’t substitute a dried seaweed product on this combine.)
  • 1 gallon compost (effectively decomposed)

Advisable Reads

A Information to Soil Fertility and Crop Well being

The Good Combine: All Goal Potting Soil Recipe

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