Sunflowers can grow quite tall, often reaching heights of 6 feet or more. When planted near marigolds, they can easily overshadow them, blocking the sunlight that marigolds need to flourish.
Furthermore, sunflowers have extensive root systems that can compete with marigolds for water and nutrients, further hindering their growth.
9. 5. Daisies: Competing for Space
Daisies, with their spreading growth habit, can quickly take over garden space, leaving little room for marigolds to grow. This competition for space can lead to overcrowding, which can stress both plants and reduce their overall health.
Additionally, daisies and marigolds may compete for similar nutrients, leading to nutrient deficiencies if not managed properly.
10. 6. Lilies: Different Watering Needs
Lilies prefer consistently moist soil, while marigolds are more drought-tolerant once established. This difference in watering needs can make it challenging to care for both plants when they are planted together.
Overwatering marigolds to meet the needs of lilies can lead to root rot and other issues, while underwatering lilies can cause them to wilt and fail to thrive.
11. 7. Tulips: Soil pH Conflicts
Tulips prefer a slightly more alkaline soil, with a pH of around 6.5 to 7.5, compared to the slightly acidic to neutral range preferred by marigolds. This difference in soil pH preferences can lead to nutrient uptake issues for both plants.
Additionally, tulips have a different growth cycle, often going dormant in the summer, which can disrupt the visual harmony of a garden when planted with marigolds.
12. 8. Pansies: Attracting Similar Pests
Pansies, like marigolds, can attract aphids and other pests. Planting them together can increase the pest pressure in the garden, leading to more significant infestations and damage.
While both plants can tolerate cooler temperatures, the increased pest presence can outweigh any potential benefits of planting them together.
13. 9. Chrysanthemums: Allelopathic Effects
Chrysanthemums are known for their allelopathic properties, meaning they release chemicals into the soil that can inhibit the growth of nearby plants. This can negatively impact marigolds, leading to stunted growth and reduced flowering.
Additionally, chrysanthemums can compete with marigolds for nutrients and space, further hindering their growth and health.
14. 10. Zinnias: Competing for Sunlight
Zinnias, like marigolds, thrive in full sun. However, they can grow quite tall and bushy, potentially overshadowing marigolds and reducing their access to sunlight.

This competition for sunlight can lead to reduced growth and flowering for marigolds, making it challenging to maintain a vibrant and healthy garden when these two plants are grown together.