Container gardening has many benefits and is ideal for a wide variety of gardeners, including novices, aging gardeners or persons with limited mobility, and those with limited time or space. Here are some tips to get you started.
1. Start with the Soil
The biggest difference between growing plants in containers and growing them in the ground is the soil. Commercial potting mixes are ideal for container gardening because they allow for adequate drainage and aeration. These mixes contain a combination of vermiculite and peat moss, and either perlite or ground pine bark for drainage and aeration. Many commercial mixtures also are fortified with fertilizer. If you plan to have an abundance of containers, consider mixing your own potting soil to save cost. Mineral soil, or soil from your garden, can be used if you add organic matter for necessary drainage. A mixture of two parts soil, two parts peat moss, and one part perlite should be fine.
2. Add Fertilizer
Commercial mixtures, fortified with fertilizer, often claim to feed plants for up to four months. Potting soils, by design, will not hold on to nutrients for more than a few weeks. Nutrient levels drop as plants use them for growth, and, with each watering.
Most commercial fertilizers contain the three primary nutrients required for plant growth: nitrogen, phosphorus and potassium. Potting mixtures often lack minor nutrients such as calcium, magnesium, sulfur and iron causing container-grown plants to turn yellow. The solution is to choose fertilizers that contain major and minor nutrients. You also can add dolomitic limestone to the potting mixture at planting time since it contains calcium and magnesium. Apply one tablespoon of lime per gallon of soil mixture.
When mixing your own soil for potting, it is best to add a premium grade fertilizer. An example would be a well-balanced fertilizer such as 5-10-15, 5-10-10, or 6-12-12 at a rate of 5 pounds per cubic yard or 3 ¼ ounces per bushel (1.25 cubic feet). Add dolomitic lime at the same rate as the fertilizer.
Supplemental fertilization should begin two to three weeks after planting. Frequency depends on what type of fertilizer you choose. For liquid soluble fertilizer, apply every two to three weeks during the growing season. For dry granular types, apply a half teaspoon for every gallon of soil every two to three weeks. Slow-release fertilizers are a good option, and will last up to three months. A teaspoonful per gallon of soil is generally recommended.
3. Choose a Container
Containers come in all shapes and forms, from beautifully glazed colorful pots to old rubber boots. Adequate drainage is the most important consideration for a container. If you choose a pot without holes for drainage, use a double pot method. To do this, pot plants in a container with drainage holes, and place it on gravel inside the pot without holes.
Size also is important. Outdoor container plants, especially fast growing ones, need adequate space for root development. Small pots restrict root growth, resulting in limited top growth. Containers that are tall (more than one foot) will take a large volume of soil to fill them completely. To save on soil, you can fill the bottom of containers with light-weight material to fill space like aluminum cans, or old nursery pots placed open-end down.
4. Plan Your Design
Designing container planting is much like traditional garden design. However, principles like form, texture, color and proper proportion are more important. For a balanced look, don’t choose plants that are more than two-thirds of the overall height of the container. For shallow or small containers, choose plants that won’t get too large or use plants with small foliage. For large or tall containers, choose plants with medium to tall mature size or those with large leaves, or both.
Successful plantings will pull the eye to the center to a thriller plant. Plants that work well in this role are salvia, grasses and Dracaena spike. Around the thriller, create a sense of flow with complementary plants or fillers. Filler plants will have a compact, upright growth. Examples are geraniums, dusty miller and heliotrope. To get a lush overflowing look, add plants that will serve as the spiller, such as sweet potato vine, verbenas and vinca vines.
By Joshua Fuder, contributing writer and agriculture and natural resources agent with UGA Extension-Cherokee County. firstname.lastname@example.org