31/08/2026
Ever wondered what soil blocking is all about? It’s a simple seed starting technique that uses free standing blocks of compressed growing mix instead of using pots, cell trays or punnets.
A hand held soil blocker is filled with moist growing mix and used to form firm, free standing cubes, each with a small indentation on top for planting the seed.
Soil blocking offers a range of benefits, but one of the most significant is the reduction of transplant shock. Because the roots aren’t confined by a container, seedlings can be transplanted with minimal disturbance. Seeds I have used for soil blocking include zinnias, cosmos, marigold, snapdragons, sunflowers and sweet peas. I think tomato’s would appreciate this too!
The individual blocks can be placed closely together on flat trays and depending on what tray you use they also allow for great bottom watering, soaking up from the tray instead of overhead watering which can be problematic for small, fragile new seedlings.
There are two sizes of blocks - micro and mini. I prefer to go straight to the minis as the micro require an extra transplanting step up which I don’t have time for!
You can use any soil blocking mix, provided it has sufficient moisture and binds well enough to hold its shape. While most mixes will work, depending what you have in them will determine the health of the growing seedling.
The recipe I used is below and on this occasion I am trialing half the tray with Herbi - Plant & Soil Food 🌱 living seedling soil which looks to be an exciting addition as the root is inoculated with beneficial fungi and bacteria after germination. I’ll let you know the results in a few weeks!
Recipe:
4 cups coconut coir, hydrated - available from most garden centres
4 cups compost (no big chunks)
2 cups vermiculite - I buy in bulk from The Hydro Centre Ltd
2 cups seed raising mix
If you are from Southland you will be familiar with cosy nook (next to vege boys!) - you can find these cheap catering trays there 😉
I’m going against my own advice here and early sowing more zinnias - excited to see what these beauties from Ash | Floral Storytelling produce!
Check back in a few weeks and I’ll show you the results!
