How to Prevent Splitting in Garden Mum Production
July 1, 2026 In a recent e-Gro Alert, W. Garrett Owen of The Ohio State University looks at practices growers can use to prevent poor branching, weak structural integrity, and other “splitting” issues during garden mum production to ensure the crop doesn’t become unmarketable.
What is “Splitting”
“Splitting” is a term used by growers to describe several related crop-quality problems, often resulting in gaps in the canopy due to misaligned (i.e., “split”) branch directions, rather than growing together in a singular, rounded shape. Splitting often becomes noticeable only later in production, but many of its problems can be identified and corrected much earlier, preventing lasting stress and damage to the plant.
How to Stop Splitting in Garden Mums
Owen suggests that growers consider the following:
Ensure Adequate Space to Prevent Crowding
One common cause of splitting in garden mums is crowding, where plants don’t receive adequate space and therefore compete for light, among other resources. Additionally, the lack of space promotes purely lateral growth, causing plants to become taller instead of wider, creating a non-uniform canopy with weak shoots.
Owen states that “final plant spacing should be based on container size, cultivar vigor, planting date, and the desired finished plant size,” with “highly vigorous cultivars and large containers generally require more space than compact cultivars or smaller containers.”
Avoiding Soft and Stretched Growth for a Strong Infrastructure
“Fertility programs should promote firm growth rather than continuous, soft extension growth,” Owen says, as the combination of “excessive fertilizer, frequent irrigation, warm temperatures, and low light” can create long internodes and soft growth in plants. This often results in stems that are initially capable of supporting growth but are much more likely to bend and break as the plant develops or when exposed to the elements. On the other hand, causing fertilizer concentration to become too low risks “reduced branching, canopy development, and crop uniformity.”
Decisions on fertilizing should be based on “substrate pH and electrical conductivity (EC), crop stage, weather conditions, and irrigation practices,” in addition to monitoring the root zone before applications. The goal of a fertility program should be to maintain nutrition levels while avoiding prolonged conditions that promote tissue stretch. However, that balance is hard to achieve, especially with the influence of outside factors (i.e., weather, pests, diseases).
Early Warning Signs of Crop Splitting
Splitting in garden mums has several warning signs to look for to prevent lasting crop damage, including:
- An upright instead of a rounded appearance
- Long internodes
- Reduced lateral branching
- Shaded and stretched lower branching
Additionally, some of the obvious and visible splitting symptoms, such as gaps, can sometimes be relegated to the bottom of the plant, rather than on the top of the canopy, making the signs easy to miss without closer inspection.
To catch these issues early, “crops should be monitored closely after periods of warm temperatures, rapid growth, repeated rainfall, or delayed spacing,” to ensure the conditions don’t permanently alter “plant size, branch strength, and the amount of competition among adjacent containers.”
For additional information on ensuring crop uniformity and, therefore, marketability in garden mums, including a deeper look at plant configuration and the proper use of plant growth regulators and netting rings, please read the full e-Gro (Electronic Grower Resources Online) alert “Keeping Garden Mums Together.” Additional and current e-Gro alert pieces from Volume 15 (2026) can be found online.
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