I am experimenting with two methods for my suburban garden in Las Vegas: container and soil bag. Soil bag gardens are as simple as they come.
How to plant in a potting soil bag:
1. Determine the bottom side of your bag. Punch drain holes into the bag then flip it over.
2. Cut an opening into the soil bag, leaving high enough sides to retain the soil.
3. Break up and even out the soil.
4. Transplant nursery plants into the soil bag. I used the Square Foot Garden method to determine plant spacing. Finish your project with watering.
I used a smaller square method for my Japanese eggplant and yellow squash. Mainly I wanted to try it...this is recommended for planting tomato plants. In the side slits, I planted garlic cloves pointed side up. You can use the slit variation for lettuces also.
I used 2 c. ft bags of GroWell Soil, which is a special mixture of 1/3 compost, 1/3 peat moss, and 1/3 coarse vermiculite (no dirt needed) known as Mel's Mix. Take this composition to your nursery and ask for the potting soil that most resembles it.
Their biggest detractor as far as I can see is the ugliness of the bags. As the plants grow, the bags will be less visible. My cousin, Katherine, uses hers to plant under trees where the root system doesn't let her dig and covers them with mulch. If the bags put you off, you can always invest in some grow bags. A solution Doug came up with was to build a frame for them, shown above. Here's another example of an attractive, sturdy box for the bags.
I have arranged my bags in a sunny spot close to my water source. Care for plants is a bit easier than row gardening. Because of the drainage, you are less likely to over water. If using Mel's Mix or something similar, no need to fertilize. Otherwise fertilize once a month.
I have green leaf and romaine lettuces, arugula, swiss chard, cabbage, broccoli, zucchini, eggplant, garlic and squash planted in my bags. With a bit of luck, I will have a delicious harvest to take to the kitchen. With a trip to the nursery for plants and soil and a few hours of planting, you could have your own harvest, too.