Best and Worst Rosemary Companion Plants

Rosemary (Salvia rosmarinus) is an evergreen shrub that is well-known for its aromatic fragrance. This plant is popular with a variety of pollinators and is covered by many due to its extensively reported health benefits. 

As with most perennial herbs, rosemary is hardy and robust. It thrives in warm and sunny locations with well-drained soil. Healthy rosemary will reward you with purple flowers dispersed throughout its needle-like leaves during the spring and summer months. 

Companion planting can enhance the growth and health of rosemary, so long as you choose the correct pairings. Some plants make great companions whilst others do not and distinguishing this can be somewhat challenging. 

Fear not because this article provides you with all the necessary information to help you choose the best rosemary companion plants and those you should avoid.

What is Companion Planting

Companion planting is the practice of creating communities of plants that provide mutual benefits to one another. It increases biodiversity which helps create a balanced ecosystem. 

First implemented around 10,000 years ago, the benefits of companion planting have been scientifically proven which is why this method is still widely used today. Traditionally used for agricultural crops, companion planting is now used for a variety of plants, from flowers to herbs. 

Companion planting is a natural and organic technique that helps plants to grow and develop by reducing their susceptibility to pests and diseases. It avoids the need to use harsh chemicals on your plants which can damage them and harm pollinators.  

One of the best examples of companion planting that beautifully illustrates the technique is known as the “Three Sisters” method. It was developed by Native American tribes who planted beans, sweetcorn, and squash together.

Although these sister plants can be grown individually, it was found they did best when grown together. The beans fix nitrogen in the soil, an essential nutrient that supports the growth of the other crops. 

Sweetcorn acts as a natural support structure for the beans to climb as they grow. The large leaves of the squashes provide shade and help retain moisture in the soil. The leaf canopy also helps suppress the growth of weeds. 

Benefits of Companion Planting

Companion planting offers a huge variety of benefits, being advantageous to the plants, the grower, and the wider ecosystem. 

Below are some of the main benefits of companion planting:  

Biological Pest Control: For the environmental and health-conscious gardeners who wish to avoid the use of chemical pesticides, biological pest control is crucial. Rather than artificial compounds, this method focuses on using living organisms to suppress pest populations. 

Certain plant species are attractive to predator insects that will feed on pests. For example, ladybugs feast on aphid pests, so plants that attract ladybugs will help keep aphid populations at bay. 

Some plants naturally repel pests through their scent. Strongly aromatic plants such as marigold, mint, and rosemary make great companion plants as their pungent scent can deter pests from finding their host plant. 

Improved Soil Health: Some plant pairings actually help to improve the overall health and condition of the soil. Plants with deep roots, such as asparagus, help to loosen the soil and improve drainage which reduces the likelihood of waterlogging. 

Nitrogen is a key nutrient for plant growth. All plants need nitrogen to grow and many require it in high amounts. Legumes make excellent companion plants because they are nitrogen fixers. They absorb nitrogen from the air and convert it to a fixed form in the soil, which can then be absorbed by neighboring plants. 

Increased Yields: It is possible to achieve maximum crop yields through companion planting as a result of a combination of benefits. This includes increasing pollination and reducing competition and pests. This is particularly advantageous for commercial growers since more and larger products can be harvested. 

Attracting Pollinators and Beneficial Insects: Pollinators such as bees, butterflies, and birds are said to be responsible for 90% of plant fertilization. 

Generally, pollinators are attracted to bright and highly scented plants, which also add color and fragrance to any garden. Some of the most attractive pollinators include rosemary, verbena, and sweet peas. 

Saves Space: Although companion planting can be beneficial to any grower, it’s especially beneficial to those with small gardens. Since companion planting requires various species to be potted in close proximity, a number of plants can be grown in a small area. 

Not only does companion planting save space, but it also saves time as you’re utilizing the space most efficiently. 

Improved Flavor: Growing your own herbs, fruits, and vegetables is rewarding because you get to consume them once they are ripe and ready. It’s possible to enhance the flavor of your edible plants through companion planting, thus eliminating the need for chemicals. 

For example, basil improves the taste of tomatoes, borage sweetens strawberries and dill elevates the flavor of corn. 

Providing Structural Support: Certain species of companion plants can act as a “living trellis” upon which other plants can climb up and grow. The oldest and most common example of this is the sweetcorn that was used as a structural support for the beans in the three sisters method. 

Other suitable companion plants for climbers include Jerusalem artichokes, sunflowers, and amaranth.

Selecting Companion Plants

The combination of companion plants you use depends on the main species you are trying to grow, the local climate, and the type of aesthetic you are aiming for, to name a few. There are some things to consider when choosing your companion plants, as incorrect combinations can result in potential drawbacks. 

Different species require different growing conditions. For example, lavender thrives in alkaline soil whilst azaleas love acidic soil, hence these two plants would not grow well together. Similarly, you should avoid pairing plants where one favor hot and arid conditions and the other prefers cool and moist conditions. 

It’s important to consider the characteristics of plants when selecting companion species. Mint is a fast-growing herb and if planted with a slow-growing species, may smother it and become invasive. 

Aesthetic value is important when wanting to curate an attractive garden. Think about what plant species will complement each other in terms of color, shape, and texture. 

You may also want to consider blooming times. For example, planting a spring-blooming plant next to a summer-blooming plant and an evergreen will ensure color and life throughout the seasons. 

Although pest resistance is a huge benefit of companion planting, grouping the wrong plants together can actually increase their susceptibility to pests and diseases. If the chosen plants are vulnerable to the same pests and diseases, then they can spread more easily. 

Best Companion Plants for Rosemary

Rosemary is a great addition to any garden due to its color, scent, and hardiness. It also makes a great companion plant because of its insect-repelling quality and ability to increase the health of surrounding plants. 

Rosemary requires little maintenance and is easy to care for. It thrives alongside a variety of other herbs, flowers, fruits, and vegetables. 

Below is a list of some of the best companion plants for rosemary: 

Herbs and Flowers

Rosemary, Lavender and Thyme companion plants
Rosemary, lavender, and thyme are excellent companion plants

Lavender: Like rosemary, lavender is native to the Mediterranean. The flowers and scents of these plants attract a variety of pollinators. Both these species thrive in warm climates and chalky, alkaline soils. They dislike shady, overly saturated, and cold conditions. The similar growing requirements save space and time, making them easy to care for. 

Thyme: Another perennial herb that is native to the Mediterranean, sage requires similar growing conditions. Sage favors poor soils and warm climates. These fragrant herbs repel insects, helping to keep your garden pest free.

Sage: Also having roots in the Mediterranean, sage prefers dry and arid conditions, meaning it’s tolerant of drought. Additionally, rosemary improves the growth and health of sage, as well as boosting its flavor. As such, these scented herbs make great companions. 

Oregano: Rosemary and oregano are another great pairing as they have complementary growing conditions. Oregano grows low but wide, allowing rosemary to protrude from it, creating a visually interesting appearance. Oregano also attracts insect predators to help keep pests at bay. 

Marigolds: The vibrant yellow and orange flowers of marigolds contrast beautifully with the purple flowers of rosemary. Both these plants are known for their insect-repelling properties, making them perfect companions to deter pests. 

Rosemary and marigold companion plants
Rosemary and marigolds work beautifully as companion plants

Chives: A great companion plant for a variety of other herbs and vegetables, chives are known to boost the growth and flavor of those it’s paired with. This fragrance also prevents insect pests from harming your plants.

Marjoram: The overall health of rosemary is increased when planted with marjoram. This plant releases chemicals into the soil that promote the growth and enhance the flavor of rosemary, and many other edible plants it’s paired with.  

Alyssum: Another flowering plant, alyssum blooms petit, white flowers. Like rosemary, its flowers attract a number of beneficial insects such as pollinators. The insect repelling property of rosemary helps prevent unwanted insects from attacking your alyssum. 

Fruits and Vegetables

Strawberries: Planting strawberries and rosemary together will boost the overall fertility of each plant. Additionally, the taste of strawberries is greatly improved by having rosemary as a companion plant. Sweet, juicy strawberries often fall victim to pests, but rosemary will help repel them as well as improve the strawberry’s resistance to them. 

Brassicas: Belonging to the cabbage family, these cruciferous vegetables are highly attractive to moths and butterflies, meaning they are susceptible to being eaten by caterpillars. The strong-smelling rosemary masks the scent of brassicas, protecting them from pests. 

Carrots: These vegetables enrich the soil which boosts the overall health of rosemary plants. The strong scent and physical barrier provided by the rosemary help protect the carrots from any pests. 

Beans: The overall health and growth of rosemary are improved by planting it next to beans. These legumes fix nitrogen from the air into the soil, which can be used by the rosemary. The aroma given off by rosemary masks the scent produced by the beans, hiding them from pests. 

Onion: The scents produced by both onions and rosemary help repel insect pests. They also bring out the flavor of one another, enhancing any dish they are used in. 

Worst Companion Plants for Rosemary

There are also some bad companion plants that can induce negative effects on your rosemary. Here are some plants to avoid:

Mint: This fast-growing herb has a tendency to become invasive, quickly taking up a lot of room with its foliage and its roots. This can lead to competition for space and resources. Additionally, they have contrasting requirements that make them incompatible. Rosemary likes dry, well-draining soil whereas mint favors damp soil. 

Cucumber: Being around 96% water, cucumbers require a lot of moisture through frequent, deep watering. However, rosemary needs dry soil and would likely become waterlogged and die if planted next to cucumbers. High nitrogen levels are also needed for cucumbers to grow, a nutrient rosemary cannot withstand high levels of. There’s a link to some great ideas for cucumber companion plants.

Basil: Although both rosemary and basil thrive in the sun, the similarities end here. Whilst rosemary likes dry conditions, basil prefers damp soil, making these two plants incompatible in terms of moisture requirement. 

Tomato: It’s recommended to keep rosemary and tomato plants apart from one another due to their difference in watering requirements. Tomato plants need plenty of watering in order to produce large, juicy fruits, whereas rosemary is like dry soil. Rosemary can also deprive the tomato of nutrients from the soil, hindering their growth and development. 

Pumpkins: Despite the insect-repelling ability of rosemary, it’s still susceptible to diseases such as root rot and powdery mildew. Pumpkins are root vegetables that are prone to mildew. They will increase the risk of rosemary falling victim to such a disease. 

Citations

fc0f28385ebd56da36c2bbe134f43736?s=150&d=mp&r=g
 | Website

Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.