Sowing seeds in soil blocks
This innovative pot-less method of making your own soil blocks and sowing seeds into them saves money and prevents transplant shock. It also reduces the use of plastic.
Hand-held soil block makers are used to create compressed blocks of growing medium, with a slight depression in the top of each one for sowing a seed. The blocks are placed side by side in a tray with holes for drainage (or they can be placed on a sheet of weed cloth).

When the roots reach the edge of the block, instead of encountering a pot wall (which makes them turn and start growing in circles) they reach the edge and are ‘air pruned’, making them stop growing and become dormant. When the block is transplanted into the ground, these roots immediately start re-growing, unlike container seedlings, which take up to five days longer to re-establish themselves while the roots learn to stop turning in circles. (By the way, they sometimes don’t stop growing in circles – I have pulled out plants when they have finished bearing and discovered that the reason they weren’t as productive as their neighbours, is that the roots are still in a tightly-wound circle.)

Hand-held soil block makers vary in sizes. The Plunter makes a single 7 cm square soil block. Metal soil block makers (available from Living Seeds) make five 4 cm square blocks at a time.

To make your own soil blocks:

  • Mix together one part coco peat with three parts fine compost. Add a handful of Fertilis earthworm castings per bucket of mix. Add Talborne Eco-Green Seedling Food according to the instructions on the packet.
  • To make the blocks you will need a fairly wet mixture. Add about two cups of water per four cups of dry mix until it is the consistency of wet cement (it should be just wet enough so when you squeeze it in your hands, it clumps together and the water drips out).

  • Press the soil block maker into the mixture and push it down firmly against the bottom of the container, using the handle. You are aiming to pack in three to four times more soil than a normal seedling pot, as it needs to withstand watering and root growth without the support of a container. Excess water will be squeezed out as you push the handle down.

  • Twist the soil block maker (to prevent the blocks sticking on the bottom) and lift at the same time.
  • Eject the block by pushing down on the plunger gently but firmly.

  • Place the blocks evenly spaced in the drainage tray or on weed cloth, leaving a slight gap between them so the roots don’t grow from one block to another.
  • Rinse the block maker in warm water before repeating.
  • Sow seeds in the depressions and cover with a layer of seedling mix to the same depth as the seed.
  • Keep moist with a mister spray.

Buy The Plunter here