My name is Tammy Sons. I am the founder/CEO of TN Nursery. We have been active in the nursery industry for over 60 years and 3 generations. I am a plant expert, and I have studied horticulture at TSU. My experience with dahlias across different environments has shown me the critical role neighboring plants play. I avoid planting cabbage and broccoli near dahlias because both vegetables attract aphids and cabbage loopers which easily move to the dahlias. Tall grasses and aggressive perennials such as mint are avoided because their competition for water and root crowding create conditions that dahlias cannot withstand. I keep mint away from my flower beds by planting it in separate pots. Another one I avoid is tomatoes. Dahlias require rich soil because heavy feeding plants can deplete necessary nutrients. I reserve a bright, distinct area that contains nutrient-dense compost soil for growing my tomatoes. Sunflowers receive their own distinct row of planting because their large roots and towering stems require separate space and light. When placed in spacious conditions with careful companion planting I give dahlias spotlight treatment in my garden design planning them as the main attraction. Tammy Sons - Founder/CEO My Website - https://www.tnnursery.net/pages/who-is-tammy-sons
Vice President of Operations & Integrator at Task Master Inc.
Answered 8 months ago
As the Operations Leader at Task Masters in Minnesota, I've seen countless landscape designs fail when dahlias are paired with incompatible plants. Through our 25+ years changing over 5,000 outdoor spaces, we've learned what works and what doesn't. Avoid planting fennel near dahlias - its aggressive root system competes for nutrients and can stunt dahlia growth. Instead, place fennel in a dedicated herb garden area where it can spread without causing harm. Gladiolus should be kept away from dahlias as they're susceptible to similar diseases that can quickly spread between them. We recommend planting gladiolus in a separate cutting garden where you can monitor disease issues independently. Tomatoes are another no-go near dahlias as they attract similar pests and can transfer viruses. In our Minnesota landscape designs, we position tomatoes in dedicated vegetable gardens with proper support structures, keeping them well away from ornamental dahlia beds. Bio: Christopher Deanovic is the Operations Leader of Task Masters, a premier landscape and home renovation company serving Minnesota since 1998. With expertise in changing outdoor spaces through thoughtful design and quality craftsmanship, Chris leads a team dedicated to creating functional, innovative outdoor living environments that improve clients' lifestyles.
Plants to Avoid Planting Next to Dahlias (and Why) 1. Tomatoes (Solanum lycopersicum) Dahlias and tomatoes are both nutrient-hungry, especially when it comes to nitrogen and potassium. Planting them together can result in competition for soil nutrients, leading to stunted blooms and weaker stems on dahlias. Additionally, both are susceptible to fungal diseases like powdery mildew and blight, increasing the risk of cross-contamination. Instead, plant tomatoes in a separate vegetable bed with ample spacing and crop rotation to reduce soil fatigue and disease buildup. 2. Cucumbers (Cucumis sativus) Cucumbers produce dense vines and large foliage that can overshadow dahlias, limiting airflow and light—both of which are essential for strong dahlia growth and flower production. Cucumbers also prefer consistent moisture, which can promote root rot in dahlias if watered too heavily. Grow cucumbers on trellises in sunnier, dedicated vegetable sections to prevent shading and airflow restriction. 3. Mint (Mentha spp.) Mint is an aggressive spreader with a tendency to dominate garden beds, often outcompeting neighboring plants like dahlias for space and nutrients. Its extensive root system can quickly overtake the area, making it hard to manage in mixed ornamental borders. Mint should be confined to containers or isolated raised beds where its growth can be controlled without affecting nearby plants. 4. Roses (Rosa spp.) While aesthetically complementary, roses and dahlias can harbor similar pests like aphids and spider mites, increasing infestation risks. Roses also require frequent feeding and pruning, potentially disturbing nearby dahlias' root zones. Plant roses in their own designated area with adequate spacing for airflow and separate maintenance schedules to reduce cross-pest issues. Bio: Gary Teates, ISA Certified Arborist and Tree Risk Assessor, has over 25 years of experience managing urban and commercial landscapes across the U.S. With a specialization in plant health care, sustainable tree management, and integrated landscape planning, he advises municipalities and property owners on best practices for long-term vegetation health and ornamental planting strategies.
When planting dahlias, you'll want to avoid putting them next to plants that attract a lot of aphids, such as fennel. Aphids are pests that can spread diseases and cause damage to your dahlias. Instead, plant fennel in an herb garden away from ornamental flower beds. Additionally, keep dahlias away from heavy feeders like sunflowers. Sunflowers can deplete the soil of nutrients that dahlias need to thrive, so it’s best to place them in separate areas or use a good amount of compost to nourish both types. Another plant to steer clear of near your dahlias is tall, dominant types like trees or large shrubs, which could overshadow and stunt the growth of your dahlias due to their size and root system. Instead, these should be planted in background areas where their shade won’t impact smaller plants. Lastly, avoid planting mint near dahlias. Mint tends to spread aggressively and can quickly take over a garden space, suffocating your dahlias. Plant mint in containers or confined spaces where it can’t spread wildly. About the author: I’m a professional horticulturist and gardening consultant with over a decade of experience specializing in ornamental flowers and sustainable gardening practices. I’ve presented at various gardening events and have been featured in multiple publications for my expertise in plant care and garden design. Let's make sure to share that headshot in a follow-up email; I'll ensure it's free from copyright issues before sending it over. This should keep your feature on track and your dahlias flourishing!