Find an empty spot, put a bag of potting soil there, and start growing potatoes, tomatoes, or greens inside it.

You can grow potatoes like these, and harvest them without having to dig them up.

RODALE NEWS, EMMAUS, PA—Over the years I’ve gardened just about everywhere I’ve lived, even in places where there was no tillable earth available. When I worked for the National Park Service in the Southwest, my yard was filled mostly with rocks. But I made a dandy garden by arranging the rocks into a rough-walled rectangle and filling the space with pickup truckloads of decades-old composted mule poop taken from the Park Service stables. Watered with the rinse water from my washing machine, that bed produced vegetables like a tiny farm—you could almost see them grow! I’ve also grown veggies in a community garden plot and in pots on balconies and rooftops when I’ve lived in large cities.

So if you want to grow some food, but don't think you can because your yard is shaded, the soil is of questionable quality or is paved over, or you don’t even have a yard, chances are there’s still a way to do it. Most vegetables can be grown in containers. A bottomless box of wood or rocks (like my Park Service garden) filled with soil mix makes an easy planter. Old buckets, shipping crates, discarded kiddie pools, or any container at least 8 inches deep will do just fine for planting and growing, as long as you cut or drill holes in the bottom so excess water can drain freely.

But there’s an even easier way, one that doesn’t require you to build anything or scrounge around for a container to repurpose. Believe it or not, the bag that your soil or potting mix comes in can become a vegetable garden! That’s right: All you have to do is leave the potting mix in the bag, cut a few holes, and plant. In a number of other countries, gardeners routinely plant many veggies in “grow bags”—plastic bags filled with potting soil—to avoid soilborne pests.

Here are three super-easy bagged vegetable projects to try:

• Potatoes are a perfect vegetable crop to grow in containers—in fact, in some ways they are even easier to grow in containers than in the ground. And if thinking "potato" doesn't make your mouth water, chances are you've never tasted the difference between store-bought and fresh-from-the-garden potatoes.

1. Buy a bag of organic potting soil, cut a few drainage holes in the bottom of it, and then stand the bag where you want to grow your crop. (Put it in a watertight tray if you don’t want to stain the surface beneath.) Potatoes are very hardy, so it’s safe to keep the bag outside as long as the nighttime temperature doesn’t drop much below freezing.

2. Cut open the top of the bag. Tuck two small potatoes about 4 inches deep into the potting mix. If you live near a garden center you may be able to buy "seed" potatoes; if not, or if you are looking for variety, try using a couple of small organic potatoes from your supermarket (potatoes that are already sprouting are ideal). Water to keep the soil moist but not soggy. Feed with a liquid organic fertilizer or compost tea (the liquid from soaking compost in water) every few weeks.

3. When flowers start to pop up on your potato plants, you can pull out a few "new" potatoes by rooting gently around in the soil with your fingers. Or harvest the whole lot anytime, before the plants start to turn yellow. Harvesting is easy: Just tip over the bag onto a sheet of plastic and pick out the fruits of your labor (no digging required). If you have space, you may want to start a new bag every few weeks from very early spring through early summer, to extend your harvest.