Companion planting with hollyhocks (Alcea rosea) involves selecting plant partners that create a mutually beneficial ecosystem. From a botanical perspective, the ideal companions will support the hollyhock's health, deter its common pests, and share similar growing conditions without competing excessively for resources.
Hollyhocks are notoriously susceptible to hollyhock rust, a fungal disease, and are often targeted by Japanese beetles. Certain companion plants can help mitigate these issues through biochemical means. The strong aromatic compounds released by plants like Garlic (Allium sativum) and Chives (Allium schoenoprasum) act as natural fungicides and insect repellents. Their root exudates can also help suppress soil-borne pathogens. Similarly, the potent scent of Lavender (Lavandula) and Catmint (Nepeta) confuses and deters pest insects, creating a protective barrier around the more vulnerable hollyhocks.
Hollyhocks are excellent attractors of pollinators, but they benefit greatly from companions that bring in a more diverse array of beneficial insects. Coneflowers (Echinacea) and Bee Balm (Monarda) have prominent, nectar-rich flowers that are highly attractive to predatory wasps and hoverflies. The larvae of these insects are voracious consumers of aphids, a common pest that can infest hollyhock buds. By providing a complementary food source, these companions ensure a stable population of natural pest controllers in the garden.
The tall, often top-heavy form of hollyhocks can be susceptible to wind damage. Sturdier, bushier plants can offer physical support and create a favorable microclimate. Foxgloves (Digitalis) and Delphiniums share the hollyhock's preference for full sun and well-draining soil, and their spiky forms provide mutual structural reinforcement against the wind. At their base, low-growing, spreading plants like Geraniums (Hardy Cranesbill) act as a living mulch. Their dense foliage shades the soil, helping to retain moisture and keep the root zone of the hollyhocks cooler, which reduces stress and water competition.
A successful plant partnership avoids direct competition for water and nutrients below the soil line. Hollyhocks possess a deep taproot that draws water and minerals from lower soil strata. Pairing them with shallow-rooted companions is therefore highly effective. Cosmos and Nasturtiums have fibrous, shallow root systems that occupy a different soil layer, minimizing competition. Furthermore, nasturtiums are a classic "trap crop," often attracting aphids away from the hollyhocks. This spatial separation of root zones allows both plants to thrive without hindering each other's growth.
