Why Black Eyed Susans And Sunflowers Are Bad Garden Companions

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Why Black Eyed Susans And Sunflowers Are Bad Garden Companions

Sunflowers and black-eyed susans, both popular garden flowers, are visually stunning and add charm to any garden space. However, gardeners are advised against planting them next to each other. There are two main reasons for this. First, both flowers require similar environmental essentials such as sunlight, water, and nutrients. When planted close together, this shared need creates competition, which can potentially hinder their natural development and result in fewer blossoms.

Another issue is that planting them too close can lead to overshadowing, depriving them of vital sunlight. Additionally, both sunflowers and black-eyed Susans are part of the Asteraceae family, making them susceptible to cross-pollination and resulting in hybrid offspring. These hybrids may not retain the unique and beloved characteristics of their parent plants, leading to unexpected blooms in form and color, which could be disappointing for garden enthusiasts seeking consistency throughout their garden.

How to successfully grow black eyed susans and sunflowers separately

Black eyed susans in garden

Katie Manchester/Shutterstock

Black eyed susans and sunflowers, two radiant garden staples, share some common care essentials but differ in planting times. For black eyed susans, you can opt to either seeds six weeks before the predicted last frost or seedlings once a frost is no longer a threat. They thrive in locations that guarantee at least six hours of direct sunlight daily. Black eyed susan plants flourish in well-draining soils, whether moist or dry, and can comfortably grow in loam, clay, or sandy soils as long as they don’t remain perpetually waterlogged. As they take root, they need consistent watering. Once established, their resilience shines through as they can endure drought spells, although periodic watering in such conditions remains beneficial. Maintenance is straightforward — deadhead faded blooms for continuous flowering and prune back to around 6 inches during autumn to support the following year’s growth.

Sunflowers, with their iconic golden hues, should be sown after the last frost of spring. They have a voracious appetite for sunlight, requiring a solid six hours or more daily. Their soil preference is well-draining with a pH ranging between 6 to 7.5. These sun-chasers need regular watering, especially when the weather turns dry. For maintenance, like black eyed susans, deadheading will lead to more blossoms, and a fall trim prepares them for a robust return the following season. Although there isn’t a set recommendation, ensure both types of plants have enough space between them so as not to compete for sun and nutrients and avoid cross-pollination.

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Dr Heidi Parkes

By Dr Heidi Parkes

Senior Information Extension Officer QLD Dept of Agriculture & Fisheries.