Grow For It! Container gardening

Anne Bettencourt
UCCE Master Gardeners of El Dorado County

Why do people want to grow outdoor plants in containers? Maybe because container gardening is a wonderful way to grow plants when a traditional garden is not possible due to lot size, poor soil quality, challenging natural features such as steep hills or possibly heavily forested property. Almost anything grown in the ground — vegetables, flowering plants, shrubs and trees — can be grown in a container. Planting containers is a great way to add a pop of color and texture to your hardscape or drought-tolerant landscape. Container gardening tends to be less time consuming for the gardener. It also allows the gardener the flexibility to change plantings with the seasons.

During the last century, when I was a child, garden containers were known as “flowerpots” and for the most part were made of terra cotta or wood. Today, garden containers come in a wide variety of sizes, materials, colors and shapes. Garden containers can be purchased online, at local nurseries, big box stores and even at chain pharmacies.

The recipe for a successful container garden requires correct measurements and the right ingredients. To start the process, it is important to determine where the planter will be located. Planter size is the next thing to consider because a planter must be the right fit for the location. A 6-inch pot may look great on a table by your front door, but a larger container might be needed to add that right pop of color and texture next to your front door.

Now that you have decided the size and location for a container garden, plant selection is the next ingredient needed for the mix. Plant selection will depend on how much sun or shade the planter will get each day. Almost any type of plant material can be grown in a container. Do you want to grow edibles, annuals or perennials? Maybe it will be a mix of many different plants.

Correct soil must be used for container gardens to thrive. Potting soils might seem to be very porous, yet they are formulated to provide good drainage while still holding enough water and nutrients for good plant growth. A good quality, commercial potting mixture is the best choice for container plantings. Garden soil is not recommended for containers because most native soils have a high percentage of clay particles. Clay compacts too easily causing moisture retention at the root level. Plants need space and oxygen at the root level to survive.

Before planting your container garden, make sure that the container being used has adequate drainage. Plants should never be planted in any container that will not drain. Some decorative planters, cachepots, do not have drainage holes and should not be used for direct planting. Carefully inspect plants before adding them to your container. Healthy, young plants are the best choice to add to a container. Remember that plants and their roots will continue to grow over time. Plants need adequate space to grow and thrive. If the planter is overcrowded, the number of plants may decline and die due to lack of adequate root space, water and nutrients. Larger, deeper containers allow roots to grow downward where they can find water and cooler temperatures during hot summer months.

Do not over water container gardens or allow them to dry out completely. Periodically check containers for these conditions by sticking your finger into the container’s potting soil. If the soil is damp, then there is no immediate need to water the planting. Adding about 1 inch of fine bark to the top of the container will help keep the soil moist during hot, dry summers in El Dorado County.

Checking to make sure the container is draining adequately is also advisable. Sometimes small pebbles and other debris will accumulate at the bottom of the container and block excess water from draining. If water pools for too long at the top of the planter, then the planter is not adequately draining. To alleviate this condition, gently place the planter on its side and place a stick or other blunt object into the drainage hole and gently move the debris preventing the water from draining.

Remember that some plants, especially vegetables such as tomatoes, zucchini, and green beans, will need to be staked or trellised. Flowering plants such as dahlias also need to be staked when they are blooming.

At times, the roots of shrubs and perennials will fill the pot and become “root bound.” Dwarf lemon and lime trees, as well as azaleas, are but a few of the plants that produce a large volume of roots when grown in a container. Signs of root bound plants include roots growing out of the drainage hole or small roots appearing on the surface of the soil. Adequate root space is needed for the plant to thrive. If a root bound plant is not moved to a larger container, the plant will die because there is not enough oxygen at the root level. When repotting a root bound plant, it is best to move the plant into a container that is only 2 to 4 inches larger than the current container.

Container gardens have specific needs regarding water and fertilizer. Water tends to evaporate more quickly in container plantings than with in-ground plantings. Clay and wooden planters are porous and will lose water more quickly than plastic or glazed ceramic planters. During times of extreme heat in our area, containers may need to be watered daily or even twice a day (morning and early evening). Deep watering is preferable over drip irrigation because the water will get down to the roots. A well-balanced granular fertilizer and light organic compost should be added to the potting mixture at the time of planting. Given the limited soil volume and porosity of potting soil, container plantings tend to lose nutrients at a greater rate than in-ground plantings. Adding a water-soluble fertilizer every seven to 14 days is recommended to keep plants thriving during the growing season.

Container gardening is a great way to outsmart subterranean pests such as gophers and moles, but fencing is needed to deter hungry deer and squirrels from munching on your beautiful container garden.

Master Gardener classes are offered monthly throughout the county. Find the class schedule at mgeldorado.ucanr.edu/Public_Education_Classes/?calendar=yes&g=56698, and recorded classes on many gardening topics at mgeldorado.ucanr.edu/Public_Education/Classes.

The Sherwood Demonstration Garden is open 9 am to noon Fridays and Saturdays through October. The garden is closed in case of rain; check the website for details at ucanr.edu/sites/EDC_Master_Gardeners/Demonstration_Garden.

Have a gardening question? Master Gardeners are working hard to answer your questions. Leave a message on the office telephone at (530) 621-5512 or use the “Ask a Master Gardener” option on the website: mgeldorado.ucanr.edu. To sign up for notices and newsletters, see ucanr.edu/master gardener e-news. Master Gardeners are also on Facebook, Instagram and Pinterest.