Rhubarb is a long-lived perennial, grown specifically for its tart, edible stalks. It remains productive in the garden for many years, making its planting location a lasting decision. Companion planting involves strategically placing different plant species near each other to create a mutually beneficial environment. This technique aims to enhance growth, deter common pests, or improve soil health. Understanding which plants support rhubarb’s unique requirements and which ones hinder its success is key to maximizing your annual harvest.
Understanding Rhubarb’s Growth Needs
Rhubarb’s fundamental requirements dictate the best choices for its companion plants. As a perennial, it develops a deep and massive root system over time, establishing itself permanently in one location. This substantial below-ground structure makes the plant a heavy feeder, requiring a high and consistent supply of nutrients, particularly nitrogen and potash, to support its vigorous annual growth. The sheer size of a mature rhubarb plant is a major factor in companion selection, as its roots can extend widely, making competition for water and nutrients a significant concern for any nearby plants. Rhubarb also benefits greatly from consistently cool, moist soil conditions, which its large, broad leaves naturally help create by shading the ground beneath them.
The Best Companion Plants for Rhubarb
One of the most beneficial groups of companions are the legumes, such as bush beans and peas, which address rhubarb’s high nitrogen demands. These plants have a symbiotic relationship with soil bacteria that convert atmospheric nitrogen into a usable form, effectively fertilizing the soil around the rhubarb. Their shallow root systems generally do not compete with the deep, established roots of the perennial rhubarb.
Aromatic herbs and alliums provide natural pest protection by confusing or repelling harmful insects. Planting chives, garlic, or onions near the rhubarb crown can deter common pests like aphids, weevils, and beetles due to their strong sulfur-containing compounds. Sage is another excellent choice, as its deep taproot naturally aerates heavy soil, and its blooms attract beneficial predatory insects.
Strawberries are a classic pairing, acting as a functional living mulch around the larger plant. Their dense, shallow root structure helps conserve soil moisture and suppresses weeds, which keeps the rhubarb’s soil cooler and reduces evaporative water loss. Similarly, the cool-weather brassicas, including kale and broccoli, appreciate the partial shade provided by rhubarb’s expansive leaves during the warmer parts of the day. Asparagus, as another deep-rooted perennial, makes a good companion because its root system helps to break up compacted soil, promoting better drainage for the rhubarb.
Plants That Should Never Be Next to Rhubarb
Certain plants actively hinder rhubarb’s growth and should be kept at a distance to prevent resource depletion and pest transfer. Heavy-feeding annuals like tomatoes, peppers, and potatoes are poor neighbors because they require the same high concentration of nutrients and water as rhubarb, leading to direct competition. This nutrient struggle can significantly weaken both the annual crops and the perennial rhubarb over time.
Sprawling vining plants, such as melons, pumpkins, and cucumbers, also create problems due to their vigorous growth habit. These plants can quickly spread their foliage over the rhubarb, blocking sunlight and inhibiting photosynthesis. Tall, competitive plants like corn should also be avoided because they cast dense shade that blocks the morning sun essential for rhubarb’s early-season vigor.
A final category of plants to avoid includes those that share common pests or exhibit allelopathy. Dock and sunflowers are known to attract the rhubarb curculio, a snout beetle that bores into and damages the stalks. Furthermore, no part of the rhubarb patch should be near black walnut trees, as they produce juglone, a potent allelochemical that is toxic to many plants and will severely stunt or kill rhubarb.