|I live in Arizona and the soil here is very rocky and acidic. Do you think I should dig a hole, take out the existing soil & rock and replace it with some compost and steer manure (is the steer manure necessary)? The sun is great here, but the soil has rocks from 0.5 to 1 inch. The best thing that grows here is cactus!
|Lucky you with all that sun! Sunflowers, especially the standard old-fashioned types, are a pretty tough lot and can stand a little abuse and some drought. They do prefer soil on the neutral to alkaline range, but still, they are tough plants. And although I almost always will recommend soil amendments if possible, it just may be in this case that they are not needed. If I were gardening there, I would try it both ways! I would take two plots, amend one and plant sunflowers in both areas and compare how they do. My guess is that they will do about the same, indicating little need for amendment for these hardy annuals. By the way, the rocks may be a plus for the tall heavy-headed sunflowers, anchoring them in the ground. Enjoy your sunny days!