Zinnias are vibrant, low-maintenance flowers that can brighten up your garden with a variety of colors, shapes, and sizes, blooming from late spring until the first frost. Though zinnias are easy to care for, to get the best results, it’s important to be mindful of what you plant next to them. These bright beauties thrive in full sun, well-draining soil, and require plenty of nutrients, so pairing them with the wrong plants can hinder their growth and health.
Experts recommend avoiding plants that cast too much shade or are heavy feeders, as they can outcompete zinnias for resources. Zinnias are also prone to powdery mildew, which thrives in crowded, stagnant conditions, so overcrowding should be avoided. Here are 15 plants to steer clear of when growing zinnias.
1. Impatiens
While impatiens add a colorful touch to shady spots, their preference for low light makes them incompatible with zinnias, which need full sun.
2. Astilbe
Astilbe thrives in shade and will struggle in the sun-loving conditions that zinnias require, making them poor companions for these bright flowers.
3. Corn
Corn is a heavy feeder and a fast grower. As it grows tall, it competes with zinnias for nutrients and casts too much shade, which could stunt the growth of zinnias.
4. Morning Glory
Morning glory vines can overtake zinnias, using their upright stems as a support. This could become a nuisance, especially if you’re hoping to cut zinnias for arrangements.
5. Bigleaf Hydrangea
Hydrangeas love shade and will suffer in the full sun that zinnias thrive in. These two should not be planted together in the same garden bed.
6. Lavender
Lavender prefers dry, sandy soil and is prone to root rot if placed next to zinnias, which require more moisture. This difference in water needs makes them poor companions.
7. Marigolds
Though marigolds are excellent at deterring pests, they release chemicals that can inhibit the growth of zinnias, making them unsuitable neighbors.
8. Cucumbers
Cucumbers, like zinnias, are heavy feeders, which means they will compete for the same nutrients. Additionally, cucumbers attract pests like cucumber beetles, which can damage zinnias.
9. Tomatoes
Tomato plants drain the soil of potassium and phosphorus, both essential for zinnias. Additionally, their sprawling vines can crowd out zinnias, leading to a lack of airflow and potential powdery mildew.
10. Pumpkins
Pumpkins, with their sprawling vines, will not only crowd out zinnias but also compete for the same nutrients. They attract the same pests, further complicating the growth of your zinnias.
11. Mint
Mint is an aggressive grower that can quickly choke out zinnias, robbing them of nutrients and space. If you love mint, it’s best to grow it in a pot rather than directly in the garden.
12. Fennel
Fennel can release chemicals that prevent zinnia seeds from germinating and can stunt the growth of young plants. It’s best to keep fennel away from your zinnias.
13. Rosemary
Rosemary prefers dry, well-drained soil and doesn’t need much water, while zinnias need regular watering. The excess moisture required by zinnias can cause root rot in rosemary.
14. Squash
Like cucumbers and pumpkins, squash is another vining plant that competes for nutrients with zinnias. It can quickly take over the space and crowd out your zinnias.
15. Sunflowers
Sunflowers are beautiful but need a lot of space and sunlight. They can shade out zinnias, hindering their growth and preventing their seeds from germinating.
To keep your zinnias healthy and blooming throughout the season, choose companion plants that share similar sun and water requirements, and avoid those that may hinder their growth. By planning your garden carefully, you’ll ensure your zinnias thrive alongside other plants in a balanced, healthy garden.
