While we don’t actually own any (yet), we’re quite taken with the wonderfully efficient soil blockers. Recently I got to use them while helping plant a couple of thousand tomato seeds with some of our mates. When I say I ‘helped’ do this, I really mean I mostly played with my 1 year old niece while my mates planted them. I did actually do some work, for at least 15 minutes – but I’m not sure that really counts. But hey, I was there, did some blocking and I liked it, really liked it. Here’s the low down on why.
Soil blocking is exactly what it says it is, where you make blocks of soil of varying sizes. To do so you use the very cool contraptions shown below. The smallest on the left if the one you usually start with (depending on the plants you’re growing) where you’re providing the seeds with just enough soil, space and nutrients to get started.
Image from here
Once they’ve poked their heads up and have two or more leaves the blocks are ready to be upgraded to the next size block. But unlike the usual transplanting methods which can be a bit (or a lot) disruptive to the seedling’s root system this technique is seamless. You simply pop the whole block into the next size block as you can see below. This means there’s no stress caused to the seedling and the root system can continue on it’s own merry way, expanding into the additional space provided.
The blocks are like babushka dolls, where one fits within another which then fits within another…. Image from here.
Another cool thing about this method (there are quite a few) is that there is no chance of the roots getting ‘root bound’ which is a common occurrence when seedlings are left in containers too long. Instead, the roots are ‘air pruned’ which means once they reach the boundary of their soil block, air prunes them from going any further, so they can develop a healthy, naturally shaped root system.
A root bound seedling on the left – a common ailment of leaving them too long in containers and seed blocking showing a healthy root system forming which has been air pruned. Image from here.
But lets backtrack a bit to the very start. To make sure your blocks have good ‘form’ and don’t crumble, you have to get the soil mix bang on. We made a mix up with the rough ratios of 3 parts worm castings (you can also use good compost), 1 part sand (river sand) and 1 part coco peat (coconut fibre). The worm castings are the ‘glue’ to the mix making sure the whole thing holds its shape, the sand provides drainage and air pockets while the coco peat does a brilliant job at holding moisture and nutrients in the block.
The mix needs to looks crumbly and when you squeeze it tightly there should only be around one drop of water coming out of it, no more. We use this great sieve do screen the mix, removing any bulky items and making sure there’s good ‘fluff’ factor. It’s made from timber lying around the garden and vermin mesh.
Once the mix is ready to go you can get going on your blocking. We used the smallest blockers as we were planting out a whole bunch of tomato seeds (which are tiny and don’t need much space). Other plants may be best to start in some of the larger blocks.
There’s a bit of technique involved to make a good ‘block’, it requires a firm, yet gentle hand and a bit of caution. But after a few goes you’ll have you method sorted and pump them out.
You can plant your blocks directly into a standard tray or make your own. James whipped up a whole bunch of these great planting flats made from timber and corflute which are super easy to stack to transport around. The downside to this design is the lack of airflow which means you can have some fungus growing on the timber. As a result we’ll be transferring the blocks into standard trays to increase the air flow factor shortly.
Fin rocking the blocking!
A little trick to be mindful of is to dunk your soil blocker into a bucket of water in between each ‘blocking’. This ensures that the blocks can slide out easily without getting caught on soil bits left behind from last time.
Once your blocks are all laid out you can plant your seeds. If you look closely you’ll notice that each block has a little hole in the middle – this is created automatically when you do the blocking and is designed for the seed to be placed perfectly in there. Once you’ve done so you can come back with a dusting of soil mix to cover them up and water them in using a spray bottle/mister thing.
A couple of weeks later and they’re now ready to be upgraded to the next size block – yay! However, due to having some older seed, some of them aren’t quite ready to move up a size yet, but that’s ok we’ll just have them at varied stages which isn’t the end of the world.
Soil blockers are one of those life changing tools which can save you bucket-loads on time and provide you with a superior product. We love their low-tech style and the results you get, so many wins with these gadgets!
- Allsun Farm: Sell a range of soil blockers
- Mr and Mrs G Grow Veggies: Good info and images for soil blocking
*Your blogger is Hannah Moloney, co-director of Good Life and lover of all things fun and garden-esk.