Height of a Protea Flower

Densely packed petals create an intricate bloom for decorating a garden.

Densely packed petals create an intricate bloom for decorating a garden.

Flowering protea shrubs (Protea spp.) offer brilliant blooms ranging in color from creamy white to deep red and grow in U.S. Department of Agriculture (USDA) plant hardiness zones 8 through 11, though different varieties have different zone ranges. Each cultivar within this genus has a specific shrub height and flower size. Although this bushy plant is highly resilient to cold and drought, depending on its variety, a number of environmental factors influences a protea's size.

Typical Size Ranges

A protea shrub's height ranges from 3 to 13 feet. The more than 100 varieties have varying sizes, providing versatility in your gardens. For example, a small variety may flank your front door while a large cultivar, such as "Ruby Blush" (Protea repens "Ruby Blush"), grown best in USDA zones 8 through 11, can decorate a garden nook in the back yard. Protea blossoms are equally differing in size. Growing from 2 to 12 inches in diameter, each blossom has numerous petals that spread like softened cactus spines. The blossom size does not match the shrub size, however. The "King Protea" (Protea cynaroides "King Protea") variety, which does best in USDA zones 8 through 11, has only a 3-foot shrub height but 12-inch wide blossoms.

Light Influences

Your protea plant will not grow to its full size without adequate light. Proteas need full sunlight, especially for developing their complex blossoms. The plants' dense foliage uses the sunlight for optimum photosynthesis, which contributes to shrub height and flower size. If you shade a protea shrub, eventually it will die back and have a yellowed appearance. Keeping a protea away from walls is a good practice. Light reflected off a home's wall makes it too hot for the protea to grow to its full potential.

Root System

Any root disturbances to a protea causes stunting. Although this shrub forms a deep taproot, its sensitive feeder roots remain close to the surface for nutrient and moisture uptake. If you damage the surface roots, such as when installing a sprinkler system, the protea cannot absorb the necessary nutrients for healthy foliage and flowering growth. The roots also need good soil drainage so they do not succumb to root rot from wet conditions. Consistent watering coupled with friable, or crumbly, soil provides the best environment for root activity and shrubbery growth.


A protea prefers acidic soil environments, typically below a pH of 6. If your soil requires fertilizer, it is imperative that you use an acidic type of fertilizer that is free of phosphorus and potassium. Other plants in your garden that need those nutrients should be fertilized separately from the protea; improper fertilizing easily harms a protea's growth prospects. As a natural alternative to fertilizing, you may keep the protea's soil composted and covered with organic mulch. The necessary nutrients naturally added into the ground from decomposition provides the best shrub growth.

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