Comfrey (Symphytum genus) is primarily recognized for its use in traditional external applications, such as soothing skin preparations and poultices. In the garden, this robust herb is highly valued as a dynamic accumulator. Its deep taproots draw up subsoil nutrients, making it an excellent ingredient for organic fertilizers and compost activators. Gardeners seek specific varieties to maximize these benefits while minimizing invasiveness. Finding a reliable source for the appropriate planting material is the first step in successful integration.
Essential Comfrey Varieties for Gardeners
Understanding the differences between comfrey varieties is important before purchasing, as invasiveness depends entirely on the species chosen. The two most common types are Symphytum officinale (Common Comfrey) and Symphytum x uplandicum (Russian Comfrey). Common Comfrey is fully fertile, producing viable seeds that can lead to aggressive spread throughout the garden.
For home cultivation, the sterile hybrid ‘Bocking 14’ is the preferred selection among experienced gardeners. This cultivar is a cross between S. officinale and S. asperum and was developed to retain beneficial traits while eliminating the risk of seeding. Since ‘Bocking 14’ does not produce viable seeds, it must be propagated exclusively through vegetative means, such as root cuttings or crown divisions. This ensures the plant remains contained to its planting location, making it a reliable, non-invasive option for nutrient accumulation and biomass production.
Primary Vendors and Acquisition Locations
The most dependable source for obtaining specific, non-seeding varieties like ‘Bocking 14’ is through online specialized herb nurseries and perennial plant vendors. These operations maintain specific mother stock to guarantee the root cuttings or crowns they sell are the sterile hybrid. Searching for vendors that explicitly advertise “comfrey root cuttings” or “Bocking 14 crowns” yields the most accurate results.
Local garden centers may carry comfrey, but availability is seasonal and the specific variety can be less reliably identified. If purchasing locally, confirm the botanical name or cultivar designation on the label to ensure you are not buying the fertile S. officinale. Local plants are usually sold as established potted specimens, which is convenient but often costs more than purchasing dormant root material.
Acquiring comfrey through seed suppliers is generally not recommended for the average home gardener. The seeds available are almost always those of the invasive Common Comfrey, and starting them is a slower and less reliable process than planting root material.
Another viable option for obtaining the ‘Bocking 14’ cultivar is through local garden swaps or community gardening groups. Since the sterile variety must be divided, experienced gardeners often have excess crowns or root material to share or sell at a low cost. Verify the source’s claim about the variety to avoid inadvertently introducing the fertile type.
Choosing the Best Planting Material
The form in which you acquire comfrey directly impacts the speed of establishment and the certainty of the variety you receive. Root cuttings and crowns represent the most common and effective method for propagating the desired sterile hybrids like ‘Bocking 14’.
Root Cuttings and Crowns
A root cutting is typically a small segment of the taproot, often 2 to 6 inches long, that contains enough stored energy to sprout a new plant. Bury cuttings horizontally about 2 to 3 inches deep in the soil. These root segments establish quickly. For sterile varieties, this is the only reliable way to ensure you are planting the correct, non-seeding cultivar. Comfrey crowns, the top section of the root where the leaf buds originate, are even faster to establish than simple root cuttings. Planting a crown vertically with the bud just below the soil surface typically results in leaves emerging within a few weeks of spring planting.
Potted Plants
Established potted plants offer the simplest starting method, as the plant is already growing and can be immediately transplanted without the waiting period required for root cuttings to sprout. This convenience comes at a higher price point, but it guarantees a successful start with minimal effort. Ensure that the potted plant is a multi-stemmed specimen rather than a single sprout started from a seed.
Seeds
Seeds are the least recommended planting material for general home use due to the high probability that they will yield the fertile, highly invasive Common Comfrey. Furthermore, the germination rate of comfrey seeds can be erratic, and the resulting plants take significantly longer to reach a useful size compared to those grown from root material.
Critical Warnings Before Planting
Before placing comfrey in the ground, understand its vigorous growth habit and the difficulty involved in its removal, which makes site selection paramount. Once established, comfrey is extremely challenging to eradicate because any small fragment of the deep taproot left in the soil can regenerate into a new plant. It is advisable to plant comfrey in a dedicated, isolated bed or a large, buried container that lacks a bottom to prevent lateral root spread. The deep taproot can reach depths of 6 to 10 feet, making standard garden barriers ineffective against vertical growth.
Safety and Toxicity
Comfrey plants contain pyrrolizidine alkaloids (PAs), compounds that can be toxic to the liver if consumed internally. Due to the risk of hepatic veno-occlusive disease, regulatory bodies advise against the internal consumption of comfrey products, including teas and dietary supplements. Gardeners should focus exclusively on utilizing comfrey for external applications, such as poultices and salves, or strictly for its agricultural benefits as a fertilizer and mulch. Some individuals with sensitive skin may experience mild irritation when handling the rough, bristly leaves and stems. Wearing garden gloves when harvesting large quantities of comfrey biomass is a simple preventative measure.