What Do You Need to Grow a Sunflower in a Planter?

Sunflower Varieties

• Any sunflower can be planted in a container. Dwarf varieties such as Music Box Mix, Big Smile and Pacino, which reach mature heights of 1 to 3 feet, are sized appropriately for standard-sized containers. Mid-sized sunflowers -- such as Dorado, Floristan, Starburst and Sonja that reach 3 to 6 feet at maturity -- are also suitable for container growing. Taller varieties such as Sundown, Full Sun or Claret should be planted in large containers.

Container

• Use a sturdy container for sunflowers, as many varieties may become top heavy when the plants are in full bloom. A container with a wide, heavy bottom will provide stability. A 1- to 2-gallon container is suitable for dwarf varieties, while a 5-gallon container will hold a medium-size sunflower. Plant large sunflowers in a large, heavy container such as a whiskey barrel. Avoid lightweight plastic containers that may tip easily. Any container you use must have at least one drainage hole, as sunflowers rot in soggy soil.

Soil

• Sunflowers grown in containers require a well-drained planting medium such as a lightweight commercial potting soil. Avoid regular garden soil, which will become hard and compacted in the container. As garden soil compacts, it shrinks from the side of the container, making effective watering difficult.

Sunlight

• Sunflowers need full sunlight in order to bloom. Without adequate sunlight, sunflowers grow tall and spindly as they strain to find available light. In poor light conditions, spindly sunflowers may fall over. Healthy sunflowers need a minimum of six hours of sunlight per day. All-day sunlight is even better.

Water

• Sunflowers are drought-tolerant plants that don't do well in soggy soil, but an occasional watering during hot summer weather is important to keep the plants healthy. Water a containerized sunflower deeply when the top of the soil feels completely dry, then allow time for the soil to dry before watering again. Check the sunflower often, as soil in containers dries quickly.