Soil Blocking [Part 2]
Part 2 on soil blocking today! If you missed part 1, we talked about the whys of soil blocking and also tools and materials to get started at home. Click here to read that before coming back for part 2.
Today we’ll discuss more of the how-to’s of soil blocking.
Whether you’ve opted for a hand held 20 blocker or you made your own mold (ice tray, little dixie cup, etc.) the concept is still the same. You’re going to need to get the soil or germination mix to the right consistency in order for the blocks to remain intact. If too dry they’ll fall apart, if too wet you won’t be able to keep the shape that you want. As with so much with gardening, it’s not necessarily an exact recipe of 1 cup soil, 1 cup water. It’s more of a trial and error to figure out how much water you will need to add to get that sticky but not soupy and not crumbly consistency.
I simply use a clean bucket to mix my seed starting mix and water and use my hand (sometimes gloved) to mix it together. If it gets too wet add a bit more soil, if it’s still too dry, a bit more water. You want it to mildly hold it’s shape when you squeeze a handful with some water dripping out when you squeeze.
If you’re using a homemade block maker, say an ice cube tray, you might want to make the soil mixture a tiny bit on the dry side. Because you don’t have something other than your fingers mechanically pressing the soil into a shape and then pressing it out, it will be easier to get out of the tray if it’s a tad drier. Firmly press your mix into each individual cube. If you can find something small and flat to press with that will be even better. I would let them sit for about an hour, maybe more, so they dry a little in their shape before attempting to remove. Carefully remove each block using a butter knife and arrange on your tray.
If you’re using a mini blocker (the 20 block maker that fits in the palm of your hand), make a mound of your soil once mixed. Press your blocker down into the middle of the mound and shimmy back and forth. When I do this I rotate it back and forth to get it into every corner until I hit the bottom of the bucket. Scrape off the excess with your hand, make the mound again, and do that all over again. I press my fingers into each block to be sure it’s packed full of soil and then plunge it into the soil one more time, this time focusing on filling the corners. Then using your hand, scraping the excess soil from the bottom so the blocks will be flat.
Now sit your entire blocker on your tray and gently depress the spring loaded handle. Sometimes you have to squeeze it in short bursts to get the blocks out.
Next is adding your seeds! Some plants need no soil coverage, only soil contact, and some need to be covered with a bit of soil for dark germination. Be gentle if needing to cover, the blocks are delicate right after they’re made. I like to use a toothpick to create a hole in the soil and then pinch closed or use your toothpick to cover after you’ve dropped your seed.
After you’ve added your seeds, you will want to get them onto some heat (heat mat WITH thermostat, remember you don’t want to cook the seeds; or use a sunny window) and cover with a dome or plastic wrap. You can even use moistened burlap to cover your trays, you’ll just need to re-wet it every other day or as needed. The dome/plastic/burlap is simply to keep in moisture. Soil blocks dry out very quickly. It’s sort of a game to let them dry out enough between watering but not so much that the soil becomes hydrophobic and they stop taking up water. Trial and error, again! (*remember to remove the dome/plastic wrap once you reach 50% germination!)
To water your soil blocks and soon to be baby seedlings, simply pour a gentle stream of water into the tray until the bottom 1/3 of the blocks are covered in water. Make sure to surround each block with enough water so that it starts wicking up water. If you add too much water, the blocks will fall apart. Let the water sit for at least a few minutes or until you see that each block has saturated itself. Any excess water should be poured off. Be careful not to dump your blocks! This was one reason, when I started, that I liked re-using foam meat trays. I would cut a small corner out so I didn’t have to tip it so far but not too far or you can’t hold any water in the tray.
Some tips:
Instead of your hand, you can try a potato masher to mix your soil and water. I find my hand works better personally.
When I need to make a big batch of mixed soil, sometimes I use a plastic cement mixing tub. It’s bigger, wider, and relatively shallow compared to a bucket and gives you some extra empty space to use when mashing the soil into your blocker.
After 1-2 plunges into the soil, I rock my blocker back and pack one side and then flip it and pack the other side. It’s hard to describe but picture the hungry hungry hippo game. This helps ensure the corners get packed (those are usually the weak links!)
You can let your extra soil dry in your bucket and simply add water when you’re ready to use it again.
Always clean your blocker as soon as you’re finished for the session. It is a HUGE pain to clean if you let the soil dry on it.
Don’t forget to label your trays so you know what seeds you put in those little blocks!
Once you have actual seedlings you can add a fish emulsion fertilizer to your water once per week (a weak dilution). Don’t do this before you have true leaves.
Once your seedlings are ready to be planted out, you’ll need to “harden them off” for increasing periods of time over about 1 week. When are seedlings ready? It depends on the seed you’re growing and also depends on the outside night temperatures (make sure you don’t start seeds too early, I know how tempting it is! See my Instagram/Facebook tips for seed starting!)
**Reason why a heat mat is a good investment if you’re going to start seeds every year: your soil is about 15 degrees cooler than your room air. Most seeds like to germinate above 75 degrees so if your home is 70-75 degrees your soil temp is only about 55-60 degrees. Likely, you will have poor germination at best!
Once you figure out seed starting, the sky is the limit for your garden! Technically, you can grow anything you want. There are certainly some “expert” seeds that are quite difficult to germinate or get to transplant size but there are so many things to grow. You’ll be on your way to your dream garden in no time!
Let me know if you have any questions or if there is anything else you want to know about soil blocking! Comment below or send me an email: emily@longlanefarmflowers.com
xo Emily