Coconut Coil Soil Blocks (peat-free)
We are embarking on our third growing season using soil blocks to start most of our veggies and many of our flowers. And after two successful growing seasons we continue to enjoy the process of creating these blocks, appreciating how well the seedlings grow and how easily they transplant and adapt once set out into the garden.
Soil blocks are known to have numerous advantages over pots in large part due to the natural air pruning that occurs when roots reach the end of the soil block, which also helps minimize transplant shock. The thing I love most about them is that I am using less plastic, and that we don’t have any potbound plants anymore. Are they more vigorous and do they exhibit less transplant shock? I want to say yes, but I didn’t really pay close enough attention to determine this for myself. Logic would say of course, so I’ll just roll with it. You can also read my original soil block post from last winter here.
This was a stellar hodge podge of cotton seedlings (far left), thyme, and my super early peppers including Hatch and Aji Amarillo. You can see our bottom watering setup in this photo and can read more in my original post here.
The traditional soil block recipe including any pre-mixes you purchase from well-respected seed companies all use a somewhat controversial, non-renewable resource, peat moss. Actually, most if not all commercial seed starting mixes contain peat moss. So what’s the big deal?
Peat moss is a seemingly abundant resources of seed starting mixes that has come under intense scrutiny—and for good reason—over the past decade. Peat bogs, depending on whose side you land on, are considered a non-renewable resource and sensitive Canadian ecosystem, and the harvesting practices of this resource permanently alters the landscape and takes centuries to recover. If the landscape is in someone else’s backyard, does that mean it doesn’t impact us?
Personally, in this age of globalism, it’s impossible for me to not think about the impact my purchases have on the broader environment. For me, every single purchase accumulates. It’s an additive effect on the environment. As an aside, I am currently working on significantly reducing my family’s single use plastic, which takes a shift in our consumer mindset and is a very active work in progress. There are alternatives to peat, and they aren’t without their tradeoffs, because everything has consequences.
I hope you already know a little—or a lot—about this peat alternative. It’s coconut coir. And I’ll be the first to admit that I was a bit skeptical a few years ago. I was concerned about the transportation costs of shipping this agricultural by-product across the Pacific Ocean to my midwestern home, a real tradeoff cost of the global lives we now live. Additionally, I’ve read it can contain high salinity content if it is processed using salt water instead of filtered water, which would not be a good thing for tender seedlings. That being said, I did not observe any major differences in growth of seedlings grown with coir vs peat moss last year, so I’m diving deeper into this peat alternative this year.
Coir is a by-product, a waste product, of an existing industry, something that has been piling up for decades (it does not decompose quickly) and accumulates year round in tropical regions around the globe. This fiber accumulates in large proportions, and has been studied, compared to peat moss, with very promising results.
These kohlrabi seedlings were among my first with coconut coir, before I made adjustments to the soil block recipe, substituting 1:1 peat to coir. I currently use 2/3 coir to 1 part peat and add extra compost instead. New recipe detailed below.
Coir, unlike peat’s acidity, is pH neutral, exhibits a slightly lower but still very functional water-holding capacity to peat, and can absorb water and re-wet itself much more readily than peat. It would make a great accompaniment to peat if you’re not ready to completely switch off peat moss. I love that it is a by-product of an industry rather than an industry in and of itself. I think of it like recycling or upcycling.
Because I only use a small proportion of coir in my soil blocks, and lesser quantity than that of peat, I am happy to share my new recipe with you. As this is my second season and first full season using coir, if I see adjustments are needed I will update this post.
Coir Soil Block Recipe
2 parts coconut coir
2 parts perlite
3 parts compost
1 part garden soil
A part is a part is a part. What do I mean? Use whatever container you’d like and that is your “part”. I use either a quart or half gallon yogurt container when making this recipe; a half gallon will yield several trays of soil blocks.
I mix all the dry ingredients together and then add the water. It usually takes about 4-6 parts water to achieve adequate moisture. You want water to drip profusely out of the mixture when you squeeze it. Learn more by watching my You Tube Tutorial.
Watch my You Tube tutorial on the basics of soil blocks, including my new recipe.
This is not an exact science. You may want to play with your proportions and moisture, and your compost may have more or less moisture than mine. I prefer to have ample leftover in my bin so I can easily stuff my soil blocker, so I always make more than I need for any given day. And any leftover mixture I simply leave in my bin and re-wet a good 30 minutes prior to needing it the next time. But most often, I add an entire new batch to the mixture and moisten the entire new batch with the leftovers mixed in the next time I make soil blocks.
We spent many seasons considering soil blocking before investing in the tool and trays. We use a 2” soil block with the standard pin. You can see all of the soil block equipment we use by visiting my Amazon storefront (full disclosure, I am an Amazon affiliate and may receive small commission on purchases made without any additional cost to you).
