Zinnias are highly favored annual flowers, celebrated for their rapid growth and vivid, colorful blooms that last throughout the summer. These popular plants are relatively easy to cultivate. However, many dramatic varieties produce tall, slender stems that struggle to bear the weight of their large flower heads. Staking provides the necessary structural support to keep the plants upright, protecting their appearance and health. This proactive measure ensures stems remain straight, which is beneficial if the flowers are intended for cutting.
Recognizing the Need for Structural Support
Staking is not required for all zinnias, but it is necessary for specific varieties and environmental conditions. The primary indicator for support is the mature height of the plant, especially for cultivars expected to grow three feet or taller. These tall varieties, like the ‘Benary’s Giant’ series, develop heavy, multi-petaled blooms that place significant stress on the main stem.
Proactive staking is more effective than waiting until a plant begins to lean or flop over. Plants should be staked when they are young, ideally when they are about one-third of their mature height. This timing allows the zinnia to grow up through the support structure, integrating the stake naturally into its form. Exposure to strong winds or heavy rain also increases the risk of stem breakage and lodging, making support necessary to prevent damage and maintain straight stems.
Selecting Staking Materials
A variety of materials can be used to provide effective support, depending on whether you are supporting individual plants or a mass planting. For single zinnias, common options include slender bamboo canes, sturdy metal rods, or thick wooden dowels. The chosen stake should be nearly the height of the mature plant to provide maximum support up to the heaviest flower heads.
For large plantings, horizontal support systems such as netting or wire mesh are often more efficient. Horticultural netting, like Hortonova, can be stretched horizontally across the planting area, allowing the zinnias to grow up through the grid for collective support. When securing the plant to a stake, use soft materials that will not chafe the stem, such as soft garden twine or Velcro plant ties. Avoid using thin wire or rough string, which can easily cut into the stem tissue as the plant grows and moves in the wind.
Installing the Supports
Proper installation of the support system is essential for the stability of the zinnia. For individual stakes, the support should be inserted into the soil 4 to 6 inches away from the main stem to avoid damaging the root system. The stake must be driven deep into the ground, burying at least one-third of its length, to ensure it remains stable against wind load.
Once the stake is secure, the zinnia stem is attached using a gentle tying technique that allows for both growth and movement. The figure-eight method is recommended: the tie material is wrapped around the stake, twisted once between the stake and the stem to create a cushioned loop, and then secured around the stem. This technique prevents the stem from rubbing directly against the hard stake, which could cause abrasive injury.
The tie should be placed just below the lowest heavy flower head to provide immediate support to the top-heavy section of the plant. For very tall zinnias, an additional tie can be placed at a mid-stem location to offer further stability. It is important to leave a loose loop around the stem, allowing a small gap for future stem thickening and natural swaying in the breeze. Regular inspection of the ties is necessary to ensure they do not become too tight and constrict the stem as the zinnia grows larger in diameter.