One of the most exciting aspects of cultivating a garden is selecting the right plants. Your options will depend on your soil type, climate, and localized environmental conditions. It’s also important to select species that are compatible with each other. Companion plants can help bring out the best features of your garden and enhance the growth of existing plants.
There’s no exact science to choosing the right companion species, but flowering plants have proven to be some of the best choices due to the benefits they impart. Apart from enhancing the visual properties of outdoor spaces, their blooms attract pollinators that may eventually take interest in your other plants. They also draw in beneficial insects that may aid in pest management. For horticulturists, there’s definitely nothing better than plants that look great, are easy to maintain, and help maintain the overall health of the garden!
Ideally, your companion planting flowers should grow and spread at a manageable rate and have fairly long-lasting blooms. Bonus features include a pleasing fragrance, which may give the plant the ability to fend off grazers. Companion plants are frequently used around vegetable patches (a practice in permaculture) as they can help protect produce until they are ripe for the picking. Listed below are an assortment of flowering annuals and perennials for all sorts of garden needs.
1) French marigold (Tagetes patula)
French marigold is cultivated all around the globe as an annual bedding plant. Shoots can reach their maximum height in just a few weeks, but they seldom grow past 1.6 feet (49 cm) tall. In summer, bright, fiery blooms begin to appear. These range in color from yellow-orange to brown and become spent after a brief bloom period. Frequent pollinators include beetles and tachinid flies.
The leaves of this species are known for producing pungent oils, which are used in the perfume industry. These same oils play an important role for the plant itself. Extracts have proven to be effective as a natural source of anti-fungal and pesticidal compounds. The whole plant is usually avoided by scent-sensitive grazers and pests.
You can plant a few rows of French marigold around pots or beds with seedlings and juicy fruits. Even the roots contain secretions that can supposedly kill nematodes. To maximize their growth, make sure the shoots receive full sun exposure. Brief frosts and cool temperatures cause the plant to die back. Collect the seeds, store them in a dry envelope, and sow them in late spring!
2) English lavender (Lavandula angustifolia)
One of the most famous flowering shrubs due to its calming fragrance, English lavender is a fantastic companion plant for herbs and wildflowers. Hardy to USDA zones 5 – 9, it favors mild, dry climates and can withstand brief drought periods. The leaves are evergreen in areas with frost-free winters. The roots thrive best in slightly alkaline, low-nutrient soils.
L. angustifolia requires good drainage to perform well. In optimal conditions, a bounty of beautifully-colored blooms lasts through summer. Fields of lavender can literally be swathed in shades of blue to violet, making them an unforgettable spectacle. Today, there are dozens of cultivars with subtle differences in color. Apart from being visually memorable, they are highly advantageous to have in the garden.
Lavender shoots and leaves are known for being pest-resistant. The most fragrant ones can repel the hungriest of grazers. The essential oils of this “queen of herbs” are extremely unagreeable to many wild animals. As a companion plant, it can help attract pollinators while diversifying your garden’s textures and colors. You can even collect sprigs of the blooming shoots and place them around the garden for good measure.
3) Borage (Borago officinalis)
Commercially cultivated for its medicinal uses, B. officinalis is an annual, flowering herb. It can tolerate a wide variety of conditions but favors well-draining substrates with medium moisture. New plants are regenerated year after year, with minimal effort, as this species readily self-seeds. Collected seeds may be germinated indoors to get a head start in the year, though seeds that were naturally cold stratified outdoors should also begin to germinate in spring.
Borage produces showy, blue flowers from June to August. The buds initially droop before opening up to reveal delicate, star-shaped blooms. These are situated at the tips of leafy, gray-green stems. Both the hairy leaves and stems are edible, whereas the flowers are frequently used as a garnish in salads and desserts. The seeds are rich in valuable fatty acids which are often used in food supplements.
This species is an ideal companion plant for other flowering herbs that attract bees. Blooms can quickly produce nectar and replenish their stores at a remarkable rate. Aphids may occasionally be found feasting on shoots, but these should eventually attract beneficial insects that will feed on them. In this sense, it can play the role of a “trap crop” for aphids and the like.
4) Garden nasturtium (Tropaeolum majus)
T. majus may commonly be referred to as monks cress, Indian cress, common nasturtium, or garden nasturtium. Although it is usually cultivated as an annual in most places, it may occur as a short-lived perennial in its native range or in areas with mild climates. It was once taxonomically classified under the Nasturtium genus (which includes watercress) but was found to be more closely related to Tropaeolum.
This species’ best features are its quirky leaves and bright flowers. The large leaves, which can extend to a diameter of 6 inches (15 cm), are disc-shaped. The underlying petiole is attached close to the center of each leaf and veins radiate outward from this point. Rainwater gathers as droplets (the lotus effect) and cleanly slip off of the water repellent surface.
The yellow to orange colored nasturtium flowers are characterized by five frilly petals. At dusk, the flowers can appear to flash in response to the dimming light, demonstrating the Elizabeth Linnaeus Phenomenon. The roots, leaves, and flowers of this companion plant are edible and are known for having antibacterial properties.
5) Pot marigold (Calendula officinalis)
This species is also commonly referred to as marigold but is not closely related to T. patula (listed above). It is a Mediterranean species that has long been cultivated throughout Europe due to its herbal and culinary uses. Although it is a perennial herb, it is quite short-lived. However, its lengthy flowering period makes up for its meager lifespan. When grown in agreeable conditions, flowers can appear all year round!
Flower colors differ according to cultivar. Some of the most popular ones have varied floret arrangements with double the usual number of petals. Double-flowered varieties include ‘Pink Surprise’ and those listed under the ‘Fiesta Gitana’ group of cultivars. The leaves of the plant are hairy and oblong-shaped. They are a complete source of nutrients for some Lepidoptera species.
Pot marigold is considered an ideal companion plant due to its versatility and tolerance for most soil types. To maintain its appearance or lengthen its bloom period, deadhead the blooms as soon as they are spent. Best results are achieved by cultivating this species in a sunny, well-draining location.
6) Garden thyme (Thymus vulgaris)
Garden thyme is a flowering perennial of the mint family (Lamiaceae). It is more popularly known for its culinary uses, though it can be cultivated as an ornamental companion plant in the garden. This herb is a woody, evergreen species with features that make it a fantastic ground cover option. The shoots grow to a maximum height of 12 inches (30 cm), and a single plant can cover a spread of 16 inches (41 cm).
Essentially a fragrant, low-growing bush, garden thyme is remarkably easy to maintain and propagate. Stem cuttings, which can be planted in spring, are more commonly used for propagation than seeds. Once clumps have matured, they are able to withstand mild frosts and droughts. The shoots do get long and leggy from time to time, but can simply be trimmed (or harvested) to maintain the plant’s appearance.
Garden thyme flowers attract butterflies and bees, making this species a perfect companion for other summer-interest plants. Although the tubular, pink-lavender flowers are small, seldom reaching more than an inch (2.5 cm) in length, they are numerous and occur densely across the surface of a bush. Among the many cultivars, intensely fragrant leaves subtly vary in color and shape but are generally grey to green-toned and narrow.
7) Sweet fennel (Foeniculum vulgare)
Most people are familiar with fennel for its nutritious bulbs and seeds, yet they may seldom associate the plant with its above-ground, vegetative features. This flowering perennial is a remarkably hardy species. Its shoots dot the dryer sections of riverbanks and coastal zones in many parts of the world. The bronze-leaved cultivar, known as ‘Nigra’ or ‘Purpureum’, is commonly used as an ornamental plant.
Foeniculum vulgare produces upright, branching stems that can grow as tall as 6 feet (though a maximum height of 3 feet or 91 cm is more common). The bright green leaves have a feathery texture and are segmented into needle-like leaflets. The flowers, which bloom in summer, occur on large inflorescences that are structured as compound umbels. Tiny and yellow, these are remarkably attractive to butterflies.
This species thrives best in enriched, regularly moistened, well-draining substrates. Its best features are brought out by full sun exposure. Note that it is considered an invasive plant in some countries, especially due to its self-seeding capacity. To prevent garden escapes, flowers can be deadheaded, or developing seed heads can be removed before they have ripened.
8) Sweet alyssum (Lobularia maritima)
L. maritima is commonly cultivated as an annual, flowering plant in temperate zones. It is a charming species with relatively small features. The fine stems are highly branched and are covered in tiny, alternately occurring leaves. The flowers, which may be present throughout the year in areas with mild climates, have a maximum diameter of just one-fourth of an inch (5 mm). Their sweet aroma attracts many pollinating insects.
The species epithet, maritima, refers to this plant’s tendency to favor coastal zones. It thrives in the calcareous soils of dunes and sandy coasts. In gardens, its low-growing features make it a splendid ground cover plant that can be used to border flower beds with taller species.
Due to their low maintenance requirements and capacity to bloom profusely, several cultivars are recipients of the RHS Award of Garden Merit. These include ‘Rosie O’Day’, ‘Violet Queen’, ‘Wonderland White’, and those under ‘Golf Series’. Bloom colors of these vary, with pink, purple, or white being more common. Those with darker-colored blooms can supposedly tolerate cooler climates.
9) Dwarf zinnia (Zinnia elegans)
When speaking of companion flowers, zinnias may be the first to come to mind due to their stunning blooms and ease of maintenance. First discovered in the Mexican state of Guerrero, wild-type zinnias were hybridized to create today’s flamboyant garden cultivars. Some of these can even produce enormous flower heads with a diameter of up to 6 inches (15 cm)!
The typical zinnia cultivar usually blooms in summer, producing solitary flowers that are perched on the tips of shoots. The florets look best under full sun exposure, which may seem to intensify their colors. The bright green leaves are lanceolate-shaped and are oppositely arranged. Dwarf cultivars have a maximum height that ranges from 6 inches (15 cm) to 3 feet (91 cm). When using this species as a companion plant, you can either opt for taller cultivars and use them as a backdrop or select shorter cultivars for the foreground.
Dwarf zinnias grow best in well-draining, intermediate substrates, such as loamy soil. They prefer warm temperatures and can tolerate dryness. If cultivating this species in temperate areas, they may need to be sown and overwintered indoors. In countries with warm regions, such as Australia and the US, Z. elegans has managed to escape ornamental use and has become naturalized in several states.
10) Cornflower (Centaurea cyanus)
The humble cornflower is an annual species that often grows in – you guessed it – cornfields. This pretty plant was once considered a weed throughout its native range. Ironically, its wild types are now endangered due to herbicide use in agriculture. Colonies that have become naturalized outside of Europe originated from strains that were distributed for ornamental use.
Also called bachelor’s button, witches’ bells, and blue bonnets due to its deep-colored flowers, C. cyanus can bloom quite profusely for weeks on end. If the shoots are deadheaded just in time, the flowering period can extend into late summer. Deadheading also prevents the plant from self-seeding and spreading uncontrollably.
Relatively disease-free and low-maintenance, the cornflower is an ideal companion species for plants that thrive in poor soils. Its shoots tend to be more productive under full sun exposure. They can reach a maximum height of 3 feet (91 cm) and may require the aid of a stake to keep them upright, especially when exposed to strong winds. Creating a wildlife or cottage garden should practically be effortless with the help of this plant!
