Last year, I started seeds in 1 1/2 deep meat trays with drain holes. After the seeds were up and growing, I took a sharp knife and sliced the soil into squares like brownies. When time to repot or plant out, all I had to do was lift out a square. Always watered from the bottom.
The potting soil was the cheap kind. Heavy : )

I also use soil blocks. I have the two inch size and the 3/4 inch size. The 2 inch size works perfectly but have had my small one come apart a few times. You have to learn where to hold onto it to keep this from happening. The first year I made my own mix and never did get it right. After that I just bought Jiffy Mix and it worked perfectly. I just made 40 two inch blocks this morning and planted them. I use the small blocks for small seeds but you have to transplant earlier than normal. It seems that I always have some "older" seed that I have kept too long. I can try it in the samll blocks with no waste like a peat pellet would be. It is just a 3/4 inch block of mix to re-use or throw in the flower bed. I don't have a need for the larger ones because I have many, many pots.
I highly recommend the 2 inch size.

Those soil block makers are obviously a great tool that do exactly what they were designed for, but why pay over $100 for one? Maybe I am missing something crucial about the process but couldn't you just buy or build a brick mold for the bigger ones? Then you could make a 4"x 6" block and just trim off the extra two inches of soil. Or couldn't you just get some scrap wood/metal and build a square of any dimensions you need?

Since I know a lot of people like very specific directions here is what I think can be done to make your own 4" soil block maker for around $10, if that.

Materials needed:
Wood: at least a 2' section of a board that is 4"x 1"
Saw: to cut the wood
Screws/drill: eight 2" wood screws should be enough
Wax paper: to line the inside of the block
Tape or glue: to attach the wax paper

1. Cut 2 pieces of wood that are 6" long
2. Cut 2 pieces of wood that are 4" long
3. Assemble the 4 pieces with screws to make a square that is 4 inches on each side (inside edge)
4. line the inside of the square with wax paper so that the soil doesn't stick to the block maker
5. Cut a piece of wood that is smaller than a 4"x 4" square maybe 3.75" x 3.75"

The wax paper would need to be replaced once in awhile as it deteriorates. These blocks would be made in place and not moved until roots are holding them together. You could just place this mold where you want it, pack it with soil, and place the smaller square on top of the mold to compress the dirt from the top. To remove the mold you would use two hands to lift the mold while holding down the top with your thumbs, once the mold starts moving it should slide out without damaging the block then the top piece can just be lifted off the soil block. This to me seems like a good solution to a homemade 4" block maker. Again hopefully I didn't miss something in the block making process but this idea seems like it would work in my mind. Let me know what you think. Save that $100 for some seeds!

cambse & weirdtrev

I wonder if weirdtrev's idea would work with the plastic container you mentioned? Why not cut the bottom out, pack the soil in with the bottom of another same-size container, and then gently lift the container, leaving a compressed round block of soil on the growing mat?

I guess the question would be whether the plastic sides without a bottom would remain rigid enough to stand some serious soil packing, not continually change shape.

cambse

I realize now you probably meant a square plastic container, not a round one.

But I guess the same questions apply.

I've never used them but will give a DIY version a try. I plan on using PVC pipe, comes in all diff sizes.

I have all three sizes. 2" are good for most seeds, 4" for squash and melons. They're all hard to keep evenly moist unless you place them on a capillary mat. But unless you get the timing just right, the roots will grow right through the mat, and tear off when you go to transplant. I think that's why the volunteer squash from my compost heap grew much bigger and faster, even though those from 4" blocks had a big headstart.

The advantage of the block makers is that they have a built-in plunger to push the block out of the mold, which keeps them in good shape. The best results come from using the plunger to hold the top of the block in place, then pulling back on the sides until the whole block is free of the mold.

Here is a link that might be useful: Block makers - Johnny's Seeds

Anney,
I did mean a square container but I like the idea of cutting out the bottom. I can ask my husband to cut a wood piece to fit the container and then it could be pushed down to release the block. With this technique even larger sizes would be possible. The problem will still be finding a container that will remain ridged enough after the bottom has been cut out. The new wooden bottom should help with that.
Also, I found a link in my bookmarks to a site giving directions on how to make soil blockers. I don't think I would try to make a 2 inch blocker as Ladbrooke makes a very good one and the 2 inch size is not all that expensive, especially considering that I have been using the same one for the last 25 years and it still works as well as it ever has.

Carole

Here is a link that might be useful: Making soil blockers

cambse

Thanks for the link!

The guy in this video shows how he uses his soil block maker. Click on Making Soilblocks under the title. He puts all his formed blocks crammed together in a plastic tray and apparently lets the growing roots intermingle, which hardly takes advantage of one of the benefits and that's to have a separate cell for each plant. But I guess he likes it as he does it -- each to his/her own!

The soil that he's blocking looks drier than I thought it would need to be.

Why not just pack the soil in the large container then cut the squares? What's the advantage of making individual blocks and then cramming them all together?

oldpea

Exactly.

As far as I can see, your method works just as well as what this guy does.

Anney,
The soil does need to be quite moist. I think that if the blocks were not so close in that video that they would crumble. They look to me as though they are supporting each other. When properly made, with moist soil, the blocks are sturdy enough to be picked up and moved onto capillary matting placed in a seeding tray. You really need some room between the blocks so that the plants develop a good blocky root system. That is one of the benefits of using a soil blocker. Nygardener says that s/he has a problem with the roots growing into the capillary matting. I have never had that happen. Perhaps the plants were allowed to get too big before transplant. Possibly some matting may allow that to happen. I get mine from Charley's Greenhouse. They are online.
The soil that you use is very important. It must be very fine grained, no shredded bark or other large pieces. It is very difficult to make blocks that will hold together with poor soil.
I like using soil blocks because it eliminates most need to deal with pots. There is no need to buy, store, clean, and sterilize pots unless you need to up pot due to being unable to transplant when the plants are ready to go in the ground. That rarely happens for me since there is a fair amount of time variation between when the plants can go into the ground and when they must go into the ground.
Other than the cost of the soil blocker, there is very little in costs involved which is another benefit to using this method.

Carole

Carole, which of Charley's capillary mats do you use? All my blocks had roots growing through the mat, but my mats were from another company. I might also have been using them wrong.

By the way, a plus of the Johnny's makers (which you can probably duplicate with a homemade one) is that each size block can be formed with an indentation on top the next smaller size. So you can germinate and grow a seed to fill out a 2" block, then move it into a 4-incher.

I found it easier to control moisture in plastic cells, since if they dry out (as they seem to periodically) you can immerse the whole section in a shallow pan of water. It seemed a little tricky to get the blocks moist but not wet. I mostly watered the capillary mat and kept my fingers crossed. Did anyone find a good way to keep the blocks watered?

Bill

Here's an interesting link to a soil block maker from 1939 - hexagonal in shape.. very interesting. The instructions here are to use it with compost. I think one could devise this rather simply with pvc and some kind of screw press to really make some good pressure.

Here is a link that might be useful: hex block maker 1939

I was really thinking this was a great idea... until I saw the video. This looks like alot of extra finicky work for no real gain. Why not just fill up the entire tray with dirt and plant your seeds?? He claims the benefit of the soil blocks is that they roots can spread out and grow together, effectively using the whole tray. Well why not just use the whole tray?

I just get used plastic inserts for free and fill em up with dirt and call it done.. hasn't costed me a dime and is easy to do on masse.

I think if there was a real benefit to this you would see commercial greenhouses using it with one huge tray sized blocker with a press that builds one full tray at a time... the guy mentioned having to do 53 more trays with the small press he was using (which is actually the biggest press i've seen sold..) no thanks.. too much fricken work!!

Bill,
I use the regular matting that they sell by the foot. I have never had a problem with roots growing into it. I think the Johnny's soil blockers are the same as the Ladbrooke. Mine also has an indentation for seeds and came with a separate 3/4 inch blocker that I never use. I put my blocks in a solid bottom seed tray and do not put seed blocks in one end of it. That allows me to pour water in that end without disturbing any of the soil blocks. The capillary matting will spread the water to all the blocks.

Esobeth,
The video is garbage. The way he does it negates the value of the seed blocker. The idea is to separate the blocks so that they stand by themselves. I use about a 3/4 inch spacing. That spacing air prunes the roots resulting in a dense cluster of roots that allows the plant to be transplanted without transplant shock. There is no point in placing the blocks next to each other allowing the roots to grow together. Roots growing together is precisely what you want to avoid.

Thanks, Carole. How many weeks do you germinate your seeds before transplanting the blocks? What brand soil do you use, or do your mix your own? Johnny's sells a mix that's formulated for soil blockers.

Hi Bill,
I believe that a younger plant is better than an older plant when it comes to transplant size. I think that trying to start plants so that they are really large when set out is counterproductive. I think that over grown transplants are set back by being held in soil blocks or even having been up potted. I try to time my plants so that I start them when the soil temperature will be good at transplant time. I know that a lot of people try to rush the season and start their plants early but I feel that a plant that has had a setback will not grow as fast as one that has not and also won't produce as much. In the long run, I think it's better to use the short end of the transplant scale. When a plant is said to be ready for transplant in 6 to 8 weeks, I plan on using the 6 week time, not the 8 week. If something happens so that I can't get the plants out at 6 weeks, I have a built in time cushion. I don't think a plant stressed from being held in less that optimum conditions, such as is necessary if they are being held too long for transplant, is a good plant. I know that a lot of people think that a bigger transplant will get them results faster but I don't agree.
I didn't know Johnny's sold a mix formulated for soil blockers. I'll have to look into that. Right now, I use a mix I buy at McConkles. I don't know if McConkles is in your neck of the woods but I really like them. They are a wholesale house for greenhouses and nurseries. I have to buy it by the bale but it lasts a long time.

I will give you all some "MORE THOUGHTS ABOUT SOIL BLOCKERS". First of all, a soil blockers compacts more soil in a cube than just "filling up a tray", actually it will then contain three times the soil in a compressed block than if it were to be loose filled. That is the real benefit. All that compressed soil is room for your roots to grow. Secondly, the video is garbage, but let's get it straight. Space your blocks if you want to air prune and keep them in the block longer. Keep 'em close (factory setting) if they'll be in for a short time and you don't want to water as much. And, cambse, if you can pack your tray with three times as much soil than filling it loose, than WOW! aren't you a genious. But, alas, you are not, as the plastic would break. Third, for those that say soil blockers are too much work would be best to go to Walmart and pickup some more plastic containers to be thrown in the dump in a year or two. Soil Blockers are a process to make your own seed starting pot and soil and seed hole, all in one; OF COURSE IT WILL USE A LITTLE EFFORT! Just wait 'till all your cheap plastic runs out. You'll wish you would've INVESTED in a soil blocker, BECAUSE THEY LAST FOREVER! So, if you're reading this listening to people who complain how expensive they are, do the math, one time investment for a trouble free product, or, year in and year out of the five and dime for a crappy plastic seed starter tray. Fourth, You do not NEED a capillary mat. It may be useful for those who aren't involved with their plants, or for those who have to work all day. Misting is the best, even for those who have a heavy hand on the water wand BECAUSE THEY ARE COMPLETELY SELF DRAINING. Fifth, make your own soil blocker with instructions at my site. Sixth, start your seeds as early as you want in soil blocks and harden them off in a senen day period while your soil warms up. don't listen to those who DON'T use soil blocks for transplanting information BECAUSE PROPERLY HARDENED OFF SOIL BLOCKS ALWAYS GROW FASTER, EARLIER, MORE YIELDS, AND HARDIER THAN OTHERS. And finally, Johhny's does NOT sell a potting soil specifically for soil blockers. It may do alright, but it is sterilized, too bad, as it won't be able to inoculate your garden soil with the good stuff. The only company in the world that sells a potting soil for a blocker is my company "Old Farm Boy", and we'll be in every store in a few years. Ask me, I'll give you a FREE SAMPLE. So, after six years and over one million blocks made, I AM THE POTTING BLOCK GURU, and I am here to serve those who want to learn.

Here is a link that might be useful: The World's Resource for Soil Block Gardening.

I still like making my seed starters out of newspaper soaked in water and then wrapper around a container the size I want to plant my seeds. They are planted with the seedlings and cause no transplant shock. Making sure none of the paper is about ground after planting.