I would offer these suggestions to enhance the ease of preparation of the garden area. First, double digging the ground is a tried and true method, but it can be labor intensive. This can present a challenge to older persons or anyone with physical limitations. An alternative would be to use the layered or “lasagna” approach to change the sod into a garden. The book Lasagna Gardening by Patricia Lanza covers this in detail, but a brief summary is to cover the grass with wet newspapers or cardboard and then build up layers of compostable material, allowing enough time to decay before planting. This kills the grass and helps to soften the earth below to make digging and planting much easier. One possible disadvantage is that the layers may not build enough heat to act as a compost pile, so weed seeds could still germinate . If time is short, then cover the cardboard with well-rotted compost and plant directly.
Second, I would suggest using old tires to create a raised bed. Most tire shops will give away old or damaged tires that they have removed from cars and trucks, after they cut the sidewall down so it cannot be used on a vehicle. Take a drill and start a hole in the remaining sidewall, then use a jigsaw to completely remove it. You could also use a handsaw if power is not available. Place the tire on top of the cardboard and cover with compostable material and soil. This gives about 2-3 square feet of planting area that will absorb heat more effectively, possibly allowing planting to start earlier. A trellis could also be added and covered with plastic sheeting to create a mini-greenhouse. Kurt Saxon discussed this method in detail in his writings if more detail is needed. – Le Chat Noir