Companion Plants for Boxwoods | Good and Bad

A very versatile evergreen shrub, the common boxwood (Buxus sempervirens) is cultivated mainly as an ornamental plant. It is a hardy and easy-to-grow plant that provides lush, green foliage all year round. 

If you are looking for companion plants for boxwoods in your garden, there is a huge variety to choose from. Vibrant, flowering plants are common companion choices as they add bursts of colour that stand out against the green foliage. Fruits, vegetables, herbs and other evergreens are also popular choices. 

Although many plants make great companions for boxwood, there are some species which make for terrible companions. Deciphering the good from bad can be a bit tricky, which is why I have provided you with all the key information in this article, to help you pick the perfect partner for your boxwood. 

What is Companion Planting?

Companion planting is a technique that involves growing plants of different species in close proximity so that they will mutually benefit one another. This method has been practised for centuries and the right pairing has been proven to result in a multitude of benefits. 

Companion planting is very eco-friendly, making it especially popular with environmentally-conscious growers. It is a natural and organic method, meaning it removes the need to use pesticides, herbicides and inorganic fertilizers, all of which can be harmful to wildlife and our health. 

Crops were among the first plants subjected to companion planting and certain pairings were found to increase the overall yield, improve the taste of the produce and be cost and time efficient. 

The Three Sisters” method is an age-old example of companion planting involving three sister plants: beans, sweetcorn and squash. The beans fix nitrogen into the soil which the sweetcorn and squash can use to help their growth. 

The sweetcorn grows strong and tall, providing a natural climbing structure for the beans to grow up. The squash has a large, dense canopy which provides shade and suppresses the growth of weeds. 

As such, “The Three Sisters” demonstrates perfect companion plant pairings, though there are many others which have been since discovered. 

Benefits of Companion Planting

This organic growing technique has so much to offer, whereby the mirroring of natural ecosystems provides benefits not only to the grower but also to the environment and surrounding wildlife too. For example:

Improves Local Biodiversity: Unlike monoculture when the same species of plant is grown in a large area, companion planting grows a diverse range of plants in the same location. This mimics natural environments, and the variety of plants promotes insect diversity. 

Assists Pollination: Almost 90% of food crops around the globe are pollinated by animals such as bees, butterflies, birds and even mammals. By growing plants that are attractive to pollinators, the probability of a higher crop yield is greatly enhanced. 

Creating Shade: Growing shorter, heat-sensitive plants under the canopies of taller, heat-tolerant plants helps to keep vulnerable plants cool during the summer heat. Dense canopies also reduce evaporation and help retain moisture in the soil.

Organic Crops: Many pesticides, herbicides and fertilizers contain chemicals that are harmful to wildlife and human health. Excess nutrients from fertilizers can run into waterways, causing algal blooms and suffocating aquatic wildlife. This is known as eutrophication and is currently a big issue.

Companion planting avoids the need to use any harmful chemicals, keeping your crops healthy and organic. 

Improves Soil Health: Nitrogen is an essential nutrient for plant growth. Legumes are known as nitrogen fixers because they take nitrogen from the air and convert it to fixed nitrogen in the soil. In this form, it can be taken up by surrounding plants to help them grow. 

Pest Management: With clever planting combinations it is possible to eliminate the need for pesticide use. Aromatic plants such as mint, lavender and basil give off strong scents which repel many insect pests. 

You can also lure pests away from your crops by planting something they are even more attracted to around it. This is known as trap cropping. 

Ground Cover: By growing lots of plants in close proximity, you reduce the amount of bare soil, meaning weeds have less space to grow. This minimizes competition between weeds and crops for nutrients and water, benefiting your plants. 

Inter-planting ground covers with your main crop also helps to reduce evaporation and erosion which is an issue with bare soil. Instead, it will promote water retention. 

Improved Flavor: Companion planting is a great method to enhance the taste of your homegrown fruit, vegetables and herbs. The right pairings can eliminate the need to use chemicals. The flavor of broccoli can be improved by planting onions and celery nearby. 

Selecting Companion Plants

Choosing poor combinations for companion planting can have negative effects on your boxwood. You should give lots of consideration prior to planting, to ensure you have chosen the best combinations. 

Some research may be required to determine whether some plants have the same growing conditions such as light requirements, soil needs and nutrient uptake, otherwise, they will likely be incompatible. 

As tempting as it may be, avoid choosing plants purely based on how they look together. This is a common mistake made when using boxwood as a topiary shrub. Instead, seek out their compatibility as this will provide you with better results. 

For example, plants that thrive in hot, arid conditions should not be grown with a plant that thrives in cool, damp conditions as the chosen environment will have adverse effects on one of the plants. 

Likewise, a plant that thrives in alkaline soil would be incompatible with a plant that needs acidic soil to thrive. 

Similarly, growing rates need to be considered. Mint grows very rapidly and can often invade the soil space of nearby plants. Additionally, mint is a heavy feeder and may deprive light feeders of essential nutrients. 

Another poor pairing would be plants that are susceptible to the same pests and diseases. If planted in close proximity, the chance of an attack will be greatly increased. 

Certain plant species are allelopathic, meaning they release chemicals into the soil to hinder the growth and development of neighboring plants. Allelopathic species such as sunflowers and black walnuts make terrible companion plants. 

Best Companion Plants for Boxwood

Boxwoods are tolerant to a variety of light conditions and can be planted in the sun or shade. They are not too fussy about soil type so long as it’s well-draining. These hardy hedge plants work well with a range of plants. 

Some of the best companion plants for boxwoods are: 

Herbs and Flowers

Roses: This perennial shrub has very similar care requirements to boxwood. Roses come in a variety of colors, all of which add class and elegance to any garden. Plant roses in front of boxwoods where their height adds dimension. 

Boxwood hedge and rose border
Boxwood hedge providing formality to a rose border

Coneflower: These large, colorful flowers add height and contrast to boxwoods. They attract pollinators due to their fragrance and are heat, cold and drought tolerant. 

Creeping Thyme: This perennial makes a great filler or ground cover plant between boxwood. Thyme is tolerant to a variety of soil conditions and can survive in shady and dry conditions. Its color and aroma attract pollinators. 

Gardenia: The white blooms of this shrubby perennial contrast against green boxwoods, whilst the glossy leaves add another texture. Boxwood provides shade to protect gardenia from the harsh midday sun.  

Foxglove: A low-maintenance perennial, foxglove can grow up to 5 feet tall, rising beautifully above your boxwood. The height and purple blooms contrast nicely with the green foliage. 

Sage: This herb is great for adding a contrasting texture against simple boxwood foliage. Sage is a fragrant herb that can thrive in poor soil conditions. 

Azalea: Another great addition to ornamental gardens, azaleas can be kept neatly pruned or left to grow large and bushy. Their flowers contrast with the green foliage making azaleas an aesthetically pleasing companion plant for boxwoods. Azaleas also like well-draining soil and have shallow roots to avoid competing with boxwood for nutrients and space. 

Tulip: The upright stature and vibrancy of tulips make them stand out in striking contrast against boxwoods. They prefer well-draining soils and tolerate light shade, making them a great companion plant for boxwood in the springtime. 

Tulips and boxwood hedge
Boxwood hedge provides a contract to a beautiful display of tulips

Coleus: Another evergreen plant, coleus boasts striking red and green foliage. It contrasts beautifully with boxwood and remains present throughout the year. It thrives in shade and is great to grow in front of boxwood. 

Monkey Grass: Like boxwood, monkey grass is commonly used for landscaping. This perennial has green foliage with purple flowers that can tolerate shady conditions. Monkey grass is drought and deer resistant, making it a great boxwood companion. 

Marigolds: A popular companion plant for many, marigolds add a splash of color to any garden and attract a variety of pollinators. 

Salvia: The upright, conical shape of these annual flowers adds color and dimension when planted in front of your boxwood. You can choose from fiery or pastel shades of flowers. 

Worst Companion Plants for Boxwood

Although a lot of plants make great companions for boxwood, a few species make terrible companions and should be avoided. The wrong pairing can harm the health of one or both of the plants.

Some plants to keep away from your boxwood are:

Silverberry: Boxwoods are a slow-growing shrub whilst silverberry shrubs grow quickly. The contrasting growth rates mean silverberry will engulf your boxwood and deprive it of nutrients and minerals due to its heavy feeding. 

Cypress: This tall growing shrub can tower over shorter boxwood, casting shade on it. Whilst boxwood is tolerant of shade, constant sunlight deprivation will cause it to wither and die. 

Bamboo: Although it makes a great ornamental plant, bamboo makes a poor companion to most species including boxwood. Bamboo grows very rapidly meaning it requires large amounts of water and nutrients, depriving the soil of them. Bamboo is also allelopathic, meaning it releases compounds that inhibit the growth of nearby plants. 

Black Walnut: A bad companion plant in general, the black walnut tree is allelopathic. Its roots release a chemical called juglone which suppresses and kill plants that sit atop its roots.   

Ivy: This hardy, invasive species are able to spread quickly and can out-compete a slow-growing boxwood for space. Depending on where it grows, ivy can cast shade on your boxwood, which can be harmful if prolonged.  

Citations 

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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.