How to prepare the soil for a greenhouse?

[rogerius]

We are planning to build a 13' x 30' green house with 12" raised beds. Unfortunately we can't find a source of triple mix in bulk in our area, just in 13/30l bags available at the store which will cost a fortune to fill up the beds. So, I need some ideas how to prepare the soil. We have available on property top soil and from our neighbor some cow manure?
Also, for area where the greenhouse will be located, do you think is better to remove the grass or just by going with the rototiller couple times will kill all the grass roots and then add the 12"tall beds?

Thanks

 

[brown40]

I have a friend who works at a composting site aka 'soil' manufacturing. She's experimented with varieties of soil mixes the past couple of years.

What she found was there are literally dozens of sdequate combinations for a variety of plant species--so long as the mineral mix, substrate texture and drainage meet a certain threshold (I can't say what that is!) plants succeed in it.

I gave her some of my recipe--it performed as well as any without exotic fertilizers and amendments.

3 parts peat
1 part perlite
1 part vermiculite
1 part compost
bone meal
blood meal
rock phosphate

That's one basic mix--close to the triple mix you're looking for but higher content of vermiculite, perlite, and nutrients--if you wish. They add mycorhyzza--soil fungus in some mixes.

It's a fairly sterile culture, and can be heat sterilized.

I'd plan on getting the existing soil/soil culture out and having a good drainage bed of crushed rock if there's no slab. Your challenge will be to create and keep a healthy biome in your 'soil'.

The existing one may be good or bad--contact between the two will spread the culture--and you'll find out quickly if any critters live there you didn't want in the mix. I'd create a barrier between them and leave the culture up to me.

The NPK organics can be swapped around if you'd rather use guano, hoof & horn, fish meal, etc. Remember to go light on whichever fertilizers you choose--you can add more, but you can't get it out so easy--especially inside.

Good luck with the project--sounds fun!

 

[forgeblast]

Look up hugekluture The Many Benefits of Hugelkultur | Permaculture Magazine i am using it in my raised beds.

 

[randy41]

if you have a way to screen the top soil and the manure isn't fresh and you mix them together you should be in good shape.

 

[troutsqueezer]

I put decomposed granite on grass and it will smother and kill it. It is also good floor material for the greenhouse.