I live in DT Corvallis. Want to convert about 1,400 SF lawn into garden. Currently digging up soil to get rid of as many weeds and grass roots as feasible. Soils turns rock hard in summer. Should I mix in compost? If so, how much? Should I cover with fabric? If so, what type. Also, a lot of my lawn would be shaded at least part of the day. What would be the best veggies/herbs to plant?
Most of the vegetables we grow here in Benton County require lots of sun during our relatively short growing season. The only vegetable I can think of, that is successful without at least 6 hours of full sun each day is lettuce.
A warning, don’t try to work your soil if it is not dry. Trying to turn clay (all of our soil is clay) at this time of year will do more damage, than good, to the soil. As for the amount of compost to work into your soil, I would start by spreading 2 to 3 inches of compost over the entire garden and then turn it into the soil. Adding compost is not a one time thing to do, it is done at least annually, or every time you change crops. I would not turn the soil or apply compost until late April or early May, if it is dry by then. Here is an excellent OSU Extension publication that will answer your questions about establishing a vegetable garden: Growing Your Own.
I strongly recommend that you consider using raised beds for your vegetables. You have so much more control over the soil, below ground pests (mice, voles, moles, etc.), watering, fertilizing, and year round vegetable growing with the addition of a cloche. I recommend that you go to the Benton County Fairgrounds, after mid-March, to see examples of raised beds.