Over the past few years I’ve been hearing a lot of talk about soil blocks, they have become very popular with market gardeners and were recently featured by Monty Don on BBC Gardeners World. Over the past few weeks I have been trying one out for myself to see if they are really as good as people claim.
So what is a soil block?
Essentially soil blocks are a replacement for plastic pots, roottrainers and peat pots.
The special “soil blocker” tool is used to make these little blocks of compost that are ideal for starting seeds for transplanting. The compost I used for this was just a regular compost (containing 50% peat) from the garden centre which I added 20% perlite too. This mix is then wet into a mud like constistancy.
The tool is then pushed into this compost mix until compact and then the soil blocks are just ejected from the tool and you are ready to plant. I watched this video which really gave me an idea of how this works and the consistancy of the soil to use.
Advantages & Disadvantages Of Soil BlocksTime - making soil blocks does take more time than just filling a few pots but is ideal if you grow a lot of seeds and the mixing can be done in bulk.
Cost - The tool to create the soil blocks is an outlay but will last a lifetime. Roottrainers are a similar alternative but are very expensive and have a relativly short (3-4 years) life span. I think long term soil blocks are good value for money.
The Mix - I just used regular compost from the garden centre with some perlite added. If the compost you buy is of low quality and contains uncomposted woodchips I don’t think it would work for soil blocks.
Germination - In my trials growing sweetcorn, lettuce, peas, and beetroot I have found the germination to be as good as any alternative. It’s hard to overwater soil blocks which I think does help with germination.
Plant Quality - Using plug trays or pots can quickly lead to the plants becoming rootbound, with soil blocks the roots are air pruned which gives a far better quality of plant when it comes to transplanting. Plant quality is really the big advantage to using soil blocks over plug trays.
I really do believe that soil blocks are a far better way to grow seedlings for transplanting. For vegetable gardeners in particular it allows a lot of plants to be grown cheaply, in large quantities and prevents any sort of transplant shock.
Overall I would highly recommend anyone growing a number of seeds every year to invest in a soil block kit.
Anyone who is new to soil blocks would be best starting with the “gift set” which contains the standard soil block size as well as the smaller Micro 20 (ideal for small seedlings like lettuce) - this set contains everything you need to get started! The tool for making soil blocks can be purchased directly from the Soil Blockers website at SoilBlockers.co.uk.