Making Soil Blocks
Seed Starting in Soil Blocks: Part 2 of 3
This lens is a continuation of Seed Starting in Soil Blocks. If you are not sure what soil blocks are you will probably want to visit that lens first. In this lens I will show you step by step how to make your soil blocks. So lets get started!
SOIL BLOCK RECIPE
This is the way I usually make my 2" soil blocks. Sometimes I vary things, but this is easy and successful for me. The mix starts off 50-50 commercial peat-lite seed starting mix and sifted compost. I throw in a little perlite if I have some, but the blocks work just fine without it. I don't usually add any fertilizer to my mix because I usually mix and use it right away. If you decide to add some fertilizer you will want to dampen the mix and let it sit for 2-3 months to 'mellow'. This is because some fertilizers, even organic ones, can give off gases that inhibit seed germination when they are first mixed with soil and dampened.
First I sift the compost through 1/4 inch hardware cloth. I made this little frame to fit right over my bucket, it didn't cost a thing, being made of all recycled materials.
Add Some Perlite, if you want to.
Add Some Water
After adding the compost, seed starting mix and perlite if you had some, mix it all together well and add some water. Let the mix sit for an hour or so before trying to make blocks, to let the peat moss soak up the water. Check on it once in awhile and stir it up well, adding more water if it's dry or stiff.
The Squeeze Test
To see if the blocking mix is wet enough do the squeeze test. When you get a handful of mix and squeeze it hard water should run out of your hand. If it doesn't, add a little more water, let the mix sit and soak it up, then try again.
This is the 2" block maker. See how I'm holding it here? I'm not pushing on the plunger, in fact, I"m holding it so that the press part will not go down. Yes, mine has some rust on it. That is what happens if you forget and leave it sitting around in the acidic peat moss for weeks on end. It eats the coating off the metal and then it starts to rust. So if you don't want yours to rust, always remember to rinse it off and put it away on a dry shelf somewhere between uses.
"Charging" the Soil Blocker
I actually do this with both hands on the blocker, but I didn't have anybody else around to take the picture. What you are doing is pushing the blocker down into the wet mix (use both hands) then sort of twist it a little to break the suction, tilt the blocker slightly and pick it up and do this again.
When I'm making a lot of blocks I usually use my wheelbarrow. I can control the wetness of the mix better with the slanted bottom. If the mix is too wet I can pile some on the high end and the water will drain to the low end. Make note that this photo shows a mix that is a little too wet. It worked for the first few sets of blocks but after that was too soupy for easy working.
If your mix gets too soupy you can add some dry mix and leave it alone for awhile to soak up the water or you can use your trowel to scoop up the mix and pack it into the blocker.
Level the Bottom
After you have managed to fill and pack all of the molds with soil mix you need to take your trowel or some other tool and scrape the excess soil off the bottom. A little like leveling the flour in the measuring cup when you are baking.
Ready, Set, Press!
Soil blocks can go into open bottomed nursery flats, sit on a piece of plywood or into home made wooden flats. You can recycle a lot of materials to hold them. Keep in mind however, that solid bottomed flats will not give you the air root pruning that makes soil blocks more desirable than plastic pots. Also, any soil blocks sitting in a solid plastic tray outside in the rain will just melt. The blocks are pretty tough and can take more handling than you would think, but if they are sitting in water they will dissolve.
In this picture I am beginning to push down on the plunger.
The motion of the actual pressing is to gently press the plunger down and then at the same time gently be picking the blocker straight up. It takes a little practice to get this motion just right, so don't be discouraged if your first blocks are not perfect. Just toss them back in the tub and try again.
TADA! Soil Blocks!
And there you go, your very first soil blocks.
Now Do It Again!
For your next row of blocks repeat the charging and leveling and set the blocker down in the tray about 1/8 of an inch away from the first row and press your second row. It does take a little bit of practice to get most of your blocks all the same size.
Note that I generally keep the 3/4 inch insert in my 2" blocker. That way I can plant anything into the hole, small seed or even something as large as corn or beans. Or I can transplant 3/4 inch cubes into the 2" block.
If Your Blocks Aren't Perfect
If you are having a hard time getting the blocker charged, your mix is probably too wet. Try adding some dry mix and letting it sit a bit. Or you can set it out in the sun and let some of the water evaporate. Or you can hold the blocker upside down and pack the mix into the cells with your trowel.
If your blocks crumble when you lift the blocker off of them then your mix might be a little too dry or you are not going straight up. Watch what you are doing and see if you are tilting the blocker as you take it off.
If the blocks in one row are not the same size it is because you did not get them all fully charged. This happens a lot in the beginning or when there is uneven pressure when you are pushing the blocker down into the mix. Just keep practicing.
If your rows of blocks are different heights it is because you have not gotten the same amount of soil mix into the blocker each time. Again, practice will help.
Even if your blocks are not perfectly identical, they are still usable. But it is easy to toss them back into the mix and try again.
Using the Mini Blocker - 3/4 inch cubes
Using the mini blocker is the same as using the 2 inch blocker. One major difference is that if you add compost you will want to screen it through 1/8 inch hardware cloth. Also you will not want to use perlite, as it is usually too big for these tiny soil blocks. It is simple and easy to use just a commercial seed starting mix which is just finely screen peat moss and fine particles of vermiculite.
Seeding and Transplanting
Because this lens is getting so long now, I will do a Part III and show you how to seed and transplant with your soil blocks. Part Three is now finished and can be found at Planting Seeds and Transplanting in Soil Blocks
I'd love to hear from you!