Companion planting involves growing different plant species together to create a mutually beneficial environment, fostering a healthier garden ecosystem. This article explores how companion planting can enhance geranium growth and resilience.
Understanding Geraniums and Companion Planting
The term “geranium” often causes confusion, as it commonly refers to plants in the genus Pelargonium, which are popular annuals known for their vibrant blooms and are not winter hardy in many climates. True Geranium species, also known as cranesbills, are typically hardy perennials that return year after year. Both Pelargonium and true Geranium belong to the same plant family, Geraniaceae, but they have distinct growing habits and characteristics. Pelargoniums often have asymmetrical flowers with two upper petals different in size and shape from the lower three, while true Geraniums usually have symmetrical flowers with five similar petals.
This practice leads to improved plant health, efficient resource utilization, and increased biodiversity. Benefits include deterring pests, attracting beneficial insects, enhancing soil conditions, and providing physical support or shade. The goal is to create a thriving plant community where each species contributes positively to its neighbors.
Beneficial Companion Plants for Geraniums
Pest Deterrents
Certain plants can help protect geraniums by repelling common pests through strong scents or by attracting predatory insects. Marigolds (Tagetes species) deter pests like nematodes and some above-ground insects through compounds released by their roots. Nasturtiums serve as a trap crop, drawing aphids away from more desirable plants and providing a food source for predatory insects. Garlic, with its potent sulfur compounds, can deter pests like aphids and whiteflies, and its antifungal properties may help protect plants from root rot.
Pollinator Attractors
Attracting beneficial pollinators like bees, butterflies, and hummingbirds is important for overall garden health and can indirectly benefit flowering plants. Lavender is highly attractive to bees and butterflies, and its strong scent can also repel certain pests, such as aphids and moths. Borage, with its star-shaped blue flowers, produces abundant nectar, attracting bees and other pollinators. This increases pollination for nearby plants and supports a healthy garden ecosystem. Catmint also attracts a variety of pollinators, including bees and butterflies, while its mint-like scent can deter deer and rabbits.
Soil Enhancers and Groundcovers
Some companion plants improve soil health, suppress weeds, or provide beneficial ground cover. Sweet alyssum (Lobularia maritima) forms a dense, low-growing carpet, acting as a living mulch to suppress weeds and conserve soil moisture. Its tiny flowers also attract small beneficial insects. Clover can be used as a living groundcover to improve soil fertility by fixing nitrogen, enriching the soil for neighboring plants. Borage’s deep taproot helps to aerate compacted soil and improve its structure, benefiting the root systems of nearby plants.
Aesthetic Partners
Plants chosen for their visual appeal can enhance the overall garden design when paired with geraniums. Petunias, with their trailing or mounding habits and wide range of colors, create a classic combination with upright geraniums in containers or beds. Coleus offers striking foliage in various colors and patterns, providing textural and chromatic contrast to geranium blooms. Dusty Miller, with its silvery, velvety foliage, offers a soft, muted backdrop that highlights the bright colors of geranium flowers while adding a unique texture to the planting.
Plants to Avoid with Geraniums
While many plants make good companions, some can hinder geranium growth due to competition, shared vulnerabilities, or allelopathy, a phenomenon where one plant produces biochemicals that inhibit the growth of others. Black walnut trees, for example, release juglone, a chemical toxic to many plants. While direct allelopathic effects on geraniums are not widely documented, avoid planting them near known allelopathic species.
Plants that are heavy feeders or have extensive root systems can compete with geraniums for water and nutrients, leading to stunted growth or reduced flowering. Additionally, planting geraniums near plants highly susceptible to the same pests or diseases (such as aphids, whiteflies, or spider mites) increases the likelihood of widespread infestations. Maintaining adequate spacing and avoiding monocultures helps mitigate these risks.
Tips for Successful Geranium Companion Planting
Successful companion planting with geraniums involves careful planning and ongoing observation. Consider the mature size of all plants to ensure adequate spacing, preventing overcrowding and competition for light, water, and nutrients.
Matching light and soil requirements is important for all companion plants to thrive alongside geraniums. Geraniums generally prefer well-drained soil and full to partial sun, so choose companions with similar needs. Regular monitoring for pests and diseases allows for early intervention, and practicing good garden hygiene, such as promptly removing diseased plant material, helps maintain a healthy environment. Observing how different plant combinations perform in your specific garden conditions allows for adjustments and improvements over time.