Recycling Old Soil

Differnet plant stake different nutrients from the soils and all at different rates. I wouldn't think 40lbs of soil would be totally depleted of any content in a single year but growing different types of plants in each container wouldn't be a bad idea since it would help balance things. (i.e. in container "A" that you grew squash in last year plant the tomatoes this year..)

Fresh topsoil brings in more nutrients and I don't think you'd even have to replace half. You could amend with 1/4 or so and be fine. If you can take out 1/4 of the soil from each container and put it in a compost bin. Then add fresh soil to the containers and add your garden scraps to the compost bin through the year (toss a few dozen worms in there too! ). Next your you won't have to buy soil, you can use the compost to amend the soil in the containers.

I'd do a complete change out of the soil with stuff from the compost bin every 3 or 4 years.

Thanks fishin'!

eoe, I have heard of container gardeners adding packing peanuts to containers. It makes them lighter and reduces the amount of planting material you need.

I'm ready to try some container gardening so I can quit fighting my clay, crappy soil. Any variety suggestions?

Annuals and veggies that you and your family and friends like. I can eat fresh tomatoes every day.
I didn't want to battle the clay soil we have here in Ga. I started with a few raised beds but my backyard just doesn't get enough sunlight. Too many trees. Now I plant in barrels for the veggies and dozens and dozens of annuals in pots and other containers. A moveable garden.
Can't wait to get started!