Vermicompost or worm compost is probably the best soil amendment product you can get if you did a good just job at maintaining your worm bin by not overfeeding, overwetting it etc... There have been a question frequently asked: can I plant in 100% vermicompost? The answer is yes you can but it is probably not a good idea. There have been several studies that have shown that too much compost or vermicompost can actually stunt plant growth. The following paper found 20-30% vermicompost being the sweet point, some experiments shown that even 5% is already doing well: https://scholar.dickinson.edu/cgi/viewcontent.cgi?referer=https://www.google.com.au/&httpsredir=1&article=1026&context=student_honors
Having a lot of surface area to cover I usually use from 10 to 20% of vermicompost in my potting mixes and if I have to plant many plants at once I wouldn’t use the mix to fill all the garden bed or pots. Instead, I would fill with some cheap mix first, then dig a hole about 20-30cm diameter and about the same in depth and I would fill that hole with my custom mix.
I based my mix with the Worm Farming Revealed’s Secret Recipe with some modifications:
- 25% of mineral rich medium: sand or garden soil and Zeolite
- 25% of carbon rich organic matter that can be shredded dry leaves, coco coir, leaf mould or even shredded cardboard
- 25% cheap potting mix
- 25% composted material: vermicompost, hot composted horse manure, chicken manure, sheep manure. The ratio between the ingredients depends on what is available at the time.
When filling a whole bed with this mix, the level drops after one season because the organic material will break down. So each autumn I would add a good layer of garden litter with more composed material on the surface and let the worms do their work. At Spring I will top up with more composted material.
I also regularly make aerated vermicompost tea and use it as soil drench and foliar spray. I will discuss about aerated compost tea in other post.