MSU Extension

Whether you live in a home that has space for an in-ground garden or just want to make a shady part of your patio, porch, or deck more beautiful, container gardening is a great way to bring the outdoors closer to your living areas. A few minutes of planning and preparation will improve your success and enjoyment of any container garden.

Site selection

Shade from overhangs, buildings or furniture affect the total number of hours the container receives sunlight, so take that into consideration when figuring out your container garden. Plants that thrive in the shade often get less than six hours of sunlight each day. Keep in mind that containers in the shade do need some sunlight, however, for the plants to bloom. If the container doesn’t get enough bright, indirect sunlight, the plant will not bloom. A good indication of how much sunlight an area receives is the presence of grass in the yard with the same amount of shade. If there is no grass growing, then there probably is not enough light for shade plants to bloom.

Container selection

The most important part of container selection is to find a container with sufficient drainage holes in the bottom. Anything, in theory, can be a container from boots to wagons to tires. A good container has numerous small holes, ideally quarter-inch holes every two to three inches of container bottom. One large hole does not permit as much drainage as numerous small holes. Drainage is especially critical for shade-loving plants since they often require less frequent watering and are easily over-watered, which can lead to disease problems.

Material

Plastic containers are lighter in weight and can be more easily moved from one spot to another, if you like to move containers as you might move your furniture. Resin containers look like clay or terracotta, but are also lightweight and easily moved. Real clay and terracotta containers are heavy and may not be as easily moved. Concrete, iron, and other materials may not be moved much, if at all. Hanging basket containers may not have solid sides, but have coconut coir or other natural material sides. Solid wall containers will generally hold more moisture longer than containers with sides of natural materials. Terra cotta is an exception to this as some moisture is lost through the unglazed clay container. Take the material into account as you determine container size and the number of plants you can easily grow in the container.

This combination of torenia, geranium, and some other plants makes a great shade container.

Size

The size of the container limits how much potting mix it can hold. Hanging baskets with coir (coconut fiber) sides in the shade will not require as much water as the same container in the sun. If you don’t want to water very often, select a larger volume container and one with solid side walls.

Potting mix

It is best to use a potting mix, one you purchase or make, rather than field soil in any container. Lighter mixes will drain better, have better root development, and will give you a lighter total container if you want to move it. Mixing equal parts (by volume) of peat moss and perlite makes a great potting mix for most plants. You can also purchase potting mixes, but avoid heavier “potting soils,” which may not drain well. Heavy soils are especially problematic for plants in the shade. Often, salt from fertilizers can build up and appear as white salty residue on the top of the potting mix.

This grape vine basket of new guinea impatiens, coleus, and creeping jenny can tolerate some sun to part shade.

Fill containers with mix and wet the dry potting mix with warm water before adding plants. In very large containers, use solid pieces of Styrofoam to fill no more than a third of the total volume of the container. Do not use Styrofoam peanuts to fill a part of the container. Often, these peanuts are now biodegradable and will “melt.” Larger pieces of Styrofoam won’t compact and will just take up space, saving some money on potting mix.

Plant selection

How many plants do I need?

As a general rule of thumb, select approximately one plant for each six inches of the diameter of the top of a round container. For example, if your container measures 18 inches across the widest part of the top, then use only three plants in that container. Often, larger diameter containers are deeper and can hold more potting mix. If you over-crowd a container, plants won’t grow as well and you will be watering very often. If your container is square, calculate the area of the top of your container (a six-inch by two foot window box has 144 square inches) and then divide by 36 square inches for each plant (the window box would hold 144/36 equals 4 plants).

What kind of plant shapes should I use?

After plant number, think about creating living art by adding a thriller, filler, spiller and (space permitting) chiller. The thriller is a tall plant that gives the container the visual element of height. The filler is the plant that is as wide as it is tall and “fills” the container. The spiller is a plant that goes over the side of the container or “spills” over the edge. The chiller is the cool plant or one that might create a visual focus or draw the eye to the container. The following table has some suggestions for the four types of plants in a shady container garden.

Color themes 

Many gardeners migrate to impatiens for the shade since there are so many colors from which to choose. Explore all the new begonias to find an alternative or compliment to impatiens. Want a plant that’s a bit more whimsical? Try torenia, also known as the clown plant. There are tons of new coleus on the market today, and you can easily find a color that suits your combination of other plants.

Color themes

Container gardens can have plants of one main color (purple, yellow, etc.) or be a blend of several related colors (yellow, orange, red), which are usually close to each other on the color wheel. Sometimes, contrasting colors can make a nice container garden. These colors appear opposite each other on the color wheel.

Color wheel.

Care and maintenance

Keep containers well-watered to keep containers healthy and actively growing. Healthy containers are more disease and insect-resistant than water-stressed or over-watered containers. As a point of reference, a 10 or 12-inch hanging basket should weigh as much as a gallon of milk if it is well watered. As the plants grow, they will use more water each day and may need to be watered twice daily in late summer.

Fertilization

Fertilize following the fertilizer’s label directions. Most containers will benefit from regular fertilization, either from slow or controlled-release fertilizer or regular application of a water-soluble fertilizer.

Deadheading and pruning

Some plants, like geraniums and petunias in a shady plant situation, will produce more blooms faster if the old, dead and spent blooms are removed. If spiller plants, like petunias, get stems or branches that are too long, leggy, or thin, you can prune or remove a half to two-thirds the total length of the stem, and often it will produce two to three new stems that grow more vigorously.