You can always set out a few containers here and there, but, with a little planning, a true container garden can rival any garden landscape. An arrangement of matching pots, with plantings that vary in scale and height, can unify steps, railings, pedestals, and landings.

For a formal look, grow the same plant in a series of matched containers and arrange them symmetrically. For a casual garden, mix shrubs, annuals, and perennials in differing containers.

And don’t forget to look up. Hanging containers, whether on an overhead beam or attached to a wall, add interest to any space. (Be sure they’re anchored securely, especially if they’re on railings or over walkways.)

Repeating patterns, whether it’s container style, the plantings themselves, or even leaf color or shape, help create a unifying effect; adding a plant or container that stands out from the others in color, size, or height is a good way to provide a focal point.

Also think about when you’ll be enjoying your garden. If you primarily visit your garden in the late afternoon into evening, consider plants that are fragrant at night. Plants with white flowers also shine in a nighttime garden.

Containers come in all shapes and sizes. You can stick with round or square containers, or look for tall cylinders, flat planters, or pots adorned with decorative edges or raised designs. You can also find specialized pots, such as strawberry pots, which can accommodate plant collections as well as strawberries.

When choosing containers, look for ones that will accommodate the final size of your plantings, or be prepared to transplant as the plants grow. Be sure to have plenty of room for roots, and be mindful if they grow down or out.

Of course, container gardens are the only choice for a balcony or rooftop, and are prized because they add color and interest to these spaces. However, when you’re planning a container garden for one of these spaces, there are certain considerations to keep in mind.

The first is weight and drainage. Pots, especially when filled with potting mix and plants, can be very heavy. If you live in a condo or apartment, you may need to check with your building association or landlord to see if there are any weight restrictions or other regulations.

Even if there are no restrictions, you may want to check on the load-bearing capacity of your structure if you want anything other than a couple of small pots.

Sun, shade, and wind are also considerations. Take a look at—and feel—your intended garden space over the course of a growing season to determine just how hospitable it is to plants. Sun can be intense on an exposed roof, and balconies may have increased light and heat reflection from walls. You may need to add some partial shade to help prevent sunburn or overexposure.

In some cases, overhead structures and site orientation may cause balconies to not get enough sun for any but the most shade-tolerant plants. In this case, choose plants that can take lower light levels.

Wind can be a major factor on rooftops and balconies. If strong winds are common, you’ll not only want to protect the plants but also take measures to be sure your containers won’t be blown over—or away. Adding screens or panels and anchoring the containers can help.