Companion planting involves strategically placing smaller plants around the base of a rose bush to enhance its growth, health, and beauty. This practice creates a visually lush, layered aesthetic while promoting the rose’s overall well-being. This symbiotic relationship helps manage common rose problems by attracting beneficial insects and suppressing weeds.
Functional Criteria for Selection
Successful underplanting requires selecting companions that do not compete with the rose for resources. Since roses have extensive root systems and are heavy feeders, neighboring plants must be minimal competitors. This means selecting species with shallow, non-aggressive roots, allowing the rose’s deeper roots to access water and nutrients unimpeded.
Environmental needs must align closely with the rose’s preference for full sun and well-drained soil. Roses thrive with at least six hours of direct sunlight daily, so companions must tolerate this exposure and not cast excessive shade on the rose’s base. Furthermore, companions should share the rose’s moderate water requirements, preferring soil that stays lightly moist but never waterlogged.
Recommended Companion Plants
Specific plants can be chosen for their ability to actively deter pests, making them natural allies for your roses. Members of the Allium family, such as chives, onions, and ornamental garlic, release a strong, sulfurous aroma that effectively masks the rose’s scent. This confusion helps deter pests like aphids and Japanese beetles, which rely on scent to locate the roses. Alliums also attract beneficial parasitic wasps, which prey on sawflies, adding a layer of biological control.
Other recommended plants are selected for their ability to attract beneficial insects that prey on rose pests. Yarrow (Achillea) is a magnet for beneficial insects like hoverflies and parasitic wasps, which manage sawfly populations and consume aphids. Parsley (Petroselinum) serves a similar function, drawing in predatory insects while also helping to repel beetles. Allowing herbs like parsley and dill to flower supports these beneficial insect populations by providing nectar and pollen.
For aesthetic purposes, low-growing plants serve as attractive groundcover, concealing the often bare lower stems of mature rose bushes. Sweet Alyssum (Lobularia maritima), with its dense, mat-forming habit, creates a carpet of tiny flowers that suppresses weeds and helps retain soil moisture. English Lavender (Lavandula) and Catmint (Nepeta) offer a beautiful contrast with their silvery foliage and spiky purple blooms, and their aromatic oils repel common pests like aphids.
Essential Spacing and Maintenance
Proper placement is essential to prevent root competition and maintain good air circulation around the rose. Companion plants should be installed at least 12 to 18 inches away from the rose cane to avoid disturbing the primary root zone. This distance ensures the rose’s roots can expand without interference and allows for easy application of fertilizer and water directly to the rose’s base.
Maintaining adequate air flow around the base of the rose is important to mitigate the risk of fungal diseases. Selecting low-growing companions helps, but ensuring they are not planted too densely will prevent moisture from becoming trapped around the rose’s lower foliage. Roses are heavy feeders and require frequent fertilization, so when feeding the rose, gardeners must account for the nutrient needs of the companions as well. However, using high-nitrogen fertilizers intended for the rose may inhibit the flowering of many companion plants, so a balanced approach is best.
Plants That Should Not Be Used
Certain plants can actively harm roses and should be avoided in the underplanting scheme. Any plant with an aggressive, spreading root system, such as some types of mint or invasive grasses, will aggressively compete for water and nutrients. These plants can quickly overwhelm the rose’s less aggressive root structure, leading to stunted growth and reduced blooming.
Plants susceptible to the same diseases as roses pose a significant cross-contamination risk. For example, members of the nightshade family (tomatoes and peppers) are prone to fungal issues like powdery mildew and blight, which easily transfer to roses. Moisture-loving plants, such as hydrangeas, should also be avoided because their need for consistently wet soil promotes fungal diseases like black spot and root rot. Large shrubs like lilacs should be kept at a distance due to their extensive root systems and susceptibility to powdery mildew.