Soil Mixtures

Question

I’m about to fill my compact VegTrug raised garden with soil (requires 210 liters of soil). I was recommended to use 1 (3 cu ft.) bag of Fox-Farms Soil conditioner; 1/2 of 1.5 cu. ft. bag of MotherEarth Biochar; and 1/2 of 1.5 cu. ft. bag of MotherEarth Worm casings. To that I was told to add my left over soil of (1) 1.5 cu. ft. bag of Fox-Farms Ocean Forest Potting soil and 1/2 of 1.5 cu. ft. bag of Roots Organic Original soil. It seems like I am still missing something in this mix formula.

Does this sound like an acceptable mix to fill the raised garden with?

Grow Scenario:
Location: So. Ca.
Herbs: Basil, Sage, Thyme
Vegetables: Green Onions, Peppers, Cherry Tomatoes, Leaf Lettuces, Kale

Thank you…

Answer 1

You have been given the most expensive potting mix formula I’ve seen! Good garden soil has 5% organic matter. The rest is silt, sand (30%) and clay. But it is too heavy for your VegTrug. Most container mixes contain a lot of sphagnum peat moss because it holds a lot of water and nutrients, perlite and compost. Your mix is substituting BioChar for some of the peat, it appears. Fox-Farm Ocean Forest soil conditioner is a combo of peat, composted wood products, worm castings and fish meal. (There is debate as to whether there are research-proven benefits to BioChar especially vs. the downsides.) The charcoal in BioChar holds water and nutrients but not as well as peat does. Adding a bag of “original soil” probably adds microbes and micronutrients if it hasn’t been sitting around too long, either at the collecting facility or factory. Worm castings and fish meal are replacing compost in your formula, it appears. You will need to add a low-nitrogen fertilizer initially and possibly nitrogen later when the fish meal and castings are used up. Your formula looks fine; what did you think it was missing?