Expert: Greg - 4/11/2005

Question
Hi Greg-

I have a small suburban house in Northern Virginia and the best place to put a vegetable/flower garden is where a concrete driveway is (or was until this weekend when I broke it up with a sledgehammer and pulled it out- very sore today).  There is now a 4-6inch depression in the yard where the driveway used to be, at the bottom is about 1 inch of marble sized gravel mixed with soil that was underlying the concrete. Underneath  the gravel is red clay subsoil.  Now I want to order some fill to prepare the space for an organic garden.  What do I order? Some combination of topsoil, leaf mulch, and manure?  The gravel is going to be very difficult to remove, I was hoping to just mix it in with the subsoil using a rototiller.  Should I dig into the subsoil and mix it with topsoil/mulch to get a deeper organic layer and mix up the gravel?  What mix of topsoil/fertilizer/mulch should I use?  Thanks much for your help!  

Answer
Hello Joseph

Yes the Gravel should pose no problem at all. You have answered you own question very well. 6" down is all you really need to worry about, unless you feel that Drainage is some sort of problem. If not then ignore digging down into the subsoil. A combination of Top Soil, and Compost should do you well, just remember that as time goes by the Compost will continue to Decompose until its gone, so it will have to be replaced with more.


If you feel that Drainage may be a Serious Problem, I suggest that you raise the Bed 4" with wood, and raise the whole Garden up. That will solve that problem, plants with a 8-10" base will do just fine.

If you mix Compost with the Top-Soil, you will need little Fertilizer, any that you use should be reduced by 50% of the suggested application rate. Different plants require different needs, but things like Peppers and Tomatos need little Fertilizers with this rich mix.

I hope this helps but if I have missed something here, don't hesiate to Follow-Up with a more in depth question


The Best of Luck
   Greg