"Soil blocks"

[Brian Hillestad]

In lieu of rockwool, I was considering using worm castings as starter blocks to insert into a raft system. Do I risk introducing disease into the system too much by doing this?

[Steve Perreault]

What a great question - I would love to do the same. However the biggest problem will be that the blocks will break up and the plant will have nothing to support it

[Carey Ma]

I did try worm casting and they worked pretty well except it has a tendency to 1. disintegrate a lil too quickly. and 2. holds a lil too much water (doesn't drain well). What works well for me is to mix 30/70 with perlite. The best results were using worm castings to coat the bigger seed or surround it with dryish worm casting, then place in net pot at least an inch higher than the high water line and cover with mixture. 3. Some packing devices compact it too hard so it lacks the capacity to transfer air/ gasses.

I believe you should be OK as long as the casting is kept in an aerobic environment and DO levels are on the higher side. I however do recommend using brewed teas instead of using lechate though some do and claim success, I don't like the risk factor.

[Brian Hillestad]

Thanks.  I was going to do a mix of castings and coconut coir.  That should allow for the air/drainage I think.  I'll let you know how it works out

[TCLynx]

I've used soil blocks (well not really soil, mine are a mix of peat, coir and worm castings) but not in a raft system.  I use them for seed starting for towers and NFT with my wicks or to plant into the dirt gardens or even into my gravel beds.

The key to avoiding pathogen problems is to make sure your worm castings are well aged.  I believe you should leave a worm bin rest/age after adding contents to it for at least 4 months to be on the safe side.

I don't think I would go for putting soil blocks into a net pot sitting down into a raft system.  It might work ok if the net pots sit well above the water line and you use wicks to get moisture up to the block but if the soil block is touching the water, I expect the problem of them dissolving too quickly or staying too wet will render less than desirable results.

But let us know if you try it and how you go about it and what your results are.

[Sahib Punjabi]

The soil blocks that I use on occasions are similar to those used by TCLynx. I use them for seed starting in my tobacco trays and the transplants go into the Vertigro pots to other verticals like the Babaylon Towers or Sahib Sandwich towers. As I have a screen at the bottom of each Vertigro pot or my verticals, and the fact that my Vertigrows drain over my media beds, I do not experience a lot dissolved solids in my water. I also use them in my recirculating wicking beds.

As TCLynx writes... 

"The key to avoiding pathogen problems is to make sure your worm castings are well aged.  I believe you should leave a worm bin rest/age after adding contents to it for at least 4 months to be on the safe side."

Looking forward to seeing what you experience.

God bless,