I just created a garden plan, including 3 raised 4x8 beds for veggies and herbs, and a few trellises for beans and such. The area of yard I'm using for the garden gets full sun, but has poor drainage. I have a few questions.

1- Should I construct the beds now and start prepping the soil with mulch, or do I not need to do that because the soil will be fresh from the garden center? Should I just wait till I'm ready to plant in April?

2- Should I put some kind of stone under the soil in the beds to imrove drainage?

Thanks all :)