local, cheap and good quality growing medium?
we used to grow arborvitae in field, but due to extremely rainy years we decided to move onto growing them in large containers (3 gallons) for better drainage. This will require a lot of substrate. We use our top soil to plant rooted cuttings into 6 inch containers (for 1 year). Obviously, we can't use our top soil for 5-thousands 3 gallon containers so we have to come up with reasonable alternative. We have a small river near our nursery so we thought we could use mixture of river bank soil, top soil, peat moss and compost. We intend to sterilize it with basamid 5G sterilant. What do you think of such substrate? could this work? There are hundreds/thousands of cubic meters of river bank soil available every year so it would be rather infinite source of almost free substrate. How much peat moss should we add to it to keep it well aerated?