I tested various proportions of vermiculite for starting seeds.
1. 100% vermiculite
2. 100% Miracle Gro potting mix
3. 50% vermiculite and 50% potting mix.
4. Potting mix on the bottom and vermiculite covering the seeds on the top.
Here are the results below from best to worst – I had 18 hollyhock seeds per tray.
- 100% Vermiculite – 8 seeds germinate
- Miracle Gro covered with Vermiculite – 7 seeds
- 50% MG + 50% Ver – 4 seeds
- 100% MG – 1 seed
Vermiculite has zero nutrients so I will be bottom watering with Jacks classic 20-20-20 with micro-nutrients. This variety is more expensive than Miracle Gro, but does a good job. Note – see my results below – this does NOT work!
Note – wear a mask when handling dry vermiculite. Wet the vermiculite as soon as possible to reduce dust particles and possible asbestos.
As you can see in the picture above, while vermiculite is great for starting seeds, since it has no nutrients, the seedlings don’t mature and grow very well. Even though I have constant bottom watering with Jacks water soluble fertilizer. The seeds in the picture are dianthus and basil. They are much healthier in the Miralcle Gro mix.
Video – Vermiculite for Starting Seeds