Stoneroot (Collinsonia verticillata)

Also known as: Whorled horse-balm

Stoneroot, or Collinsonia canadensis, is a perennial herb notable for its clusters of small, yellow flowers that grow around its square stems. The plant thrives in shaded, moist woodland areas, favoring rich, loamy soil often found near streams. It features large, heart-shaped leaves with serrated edges that capture filtered sunlight, and its sturdy stems can grow up to 3 feet tall. The lemony scent released when the leaves are crushed is another distinct characteristic of this herb.

In This Article

Care Tips Water Sunlight Temperature Soil Fertilize Prune Propagation Repotting

Attributes of Stoneroot

Lifespan

Perennial

Plant Type

Herb

Plant Height

30-90 cm

Spread

30-60 cm

Leaf Color

Green

Flower Size

2.5 cm

Flower Color

Yellow

Images of Stoneroot

Quickly Identify Stoneroot

Square stems and opposite leaf arrangement typical of the mint family.

Large, broad leaves with toothed margins emitting a pleasant aroma when crushed.

Tiered whorls of yellow, tubular flowers in vertical inflorescence up to 3 feet (90 cm) tall.

Distinct lavender to whitish-pink flowers in clusters, with fringed corolla lips.

Small nutlet fruits with hardened surfaces in varying shades of brown, resembling miniature nuts.

Scientific Classification of Stoneroot

Phylum

Vascular plants

Class

Dicotyledons

Order

Lamiales

Family

Mint

Genus

Horsebalms

Species

Stoneroot

Planting and Growing of Stoneroot

Care Difficulty

Easy

Watering Schedule

Every 2 days

Sunlight Requirements

Partial sun

Sunshine Duration

6-10 hours

Ideal Temperature

60-75℉

Soil Type

Potting Mix, Peat Mix

Soil pH

6.5-7.5

Fertilizer Type

Balanced

Pruning Season

Spring, Summer

Pruning Area

Branches, Leaves

Pruning Frequency

2 times a year

Repotting Season

Spring

Pot Type

Plastic, Ceramic

How to Water Stoneroot?

For Collinsonia verticillata, it's essential to provide a moderate amount of water, around 250 ml per watering session. This plant prefers its soil to be consistently moist but not waterlogged. You should water until you notice the water gently seeping out of the drainage holes at the bottom of the pot, which indicates that the roots have been thoroughly saturated.

What are the symptoms of an underwatered Stoneroot? ›

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What are the symptoms of an overwatered Stoneroot? ›

How to save an overwatered Stoneroot? ›

What Are the Sunlight Requirements for Stoneroot?

Sunlight Requirements: Partial sun, Full shade

Duration of light: 4 to 6 hours daily

Partial to full shade is ideal for Collinsonia verticillata, fostering a balanced environment where it can thrive without the stress of overheating. Adequate shade supports healthy foliage and robust flowering.

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What Is the Ideal Temperature Range for Stoneroot?

Ideal Temperature: 60 ~ 75℉

The ideal temperature range for Collinsonia verticillata is between 60°F and 75°F. This range provides the optimal conditions for its growth, allowing the plant to thrive well. Maintaining this temperature range helps in ensuring that the plant receives adequate warmth for photosynthesis and nutrient uptake, while avoiding stress from high temperatures.

What Soil is Best for Stoneroot?

Soil type: Loam, Sandy loam, Clay soil

Soil PH: 6.5 ~ 7.5

Collinsonia verticillata thrives in well-drained soil, preventing waterlogging around its roots which can cause rot. Adequate drainage ensures the plant's roots receive necessary oxygen, promoting healthy growth. This plant benefits from soil rich in organic matter, providing essential nutrients that enhance growth and flowering. Organic soil improves water retention and structure, supporting the plant's stability and health. Collinsonia verticillata prefers soil that retains moderate moisture without being soggy. Consistent moisture levels prevent stress, ensuring vibrant foliage and robust health.

How to Fertilize Stoneroot?

Fertilizer type: Balanced

For Collinsonia verticillata, it's essential to use a balanced liquid fertilizer diluted to half strength, about 5 mL per liter of water. When using slow-release granules, apply around 25 grams per square meter. These amounts ensure the plant receives sufficient nutrients without overwhelming it.

How to Prune Stoneroot?

Pruning Time: Spring, Summer

Collinsonia verticillata benefits from regular deadheading to promote blooming. Focus on removing spent flowers and damaged stems, which enhances overall plant health and encourages bushier growth. Start pruning by cutting back about one-third of the plant's height. Always cut at an angle just above a leaf node, which will help the plant redirect energy and sprout new growth more efficiently. More About Pruning Techniques→

How to Propagate Stoneroot plant?

Propagate Time: Spring, Early spring, Late spring

Collect seeds from mature Collinsonia verticillata plants at the end of the growing season. Clean and dry the seeds thoroughly. Store them in a cool, dry place until ready to plant in early spring.

In early spring, fill a seed tray with a seed-starting mix. Sow the seeds evenly over the surface and cover them lightly with a thin layer of soil. Water gently to keep the soil moist but not waterlogged.

In spring or early autumn, dig up mature plants using a garden fork. Carefully separate the root clump into smaller sections, making sure each section has a healthy root system and some top growth. Replant the divisions at the same depth they were growing before.

More About Propagating Techniques→

How to Repot Stoneroot plant?

Repotting frequency: Every 2-3 years

Collinsonia verticillata shows signs of needing repotting when its roots begin to outgrow the current container or penetrate through drainage holes. Additionally, a noticeable slowdown in growth or poor water retention are key indicators. Repotting during spring or summer ensures that the plant has optimal growing conditions to recover from transplant shock.

Select a pot that is about one or two sizes larger than the current one. The new pot should have ample drainage holes to avoid waterlogging, preventing root rot and ensuring healthy growth. Opt for a material that is breathable like terracotta, which facilitates air circulation to the roots, promoting a thriving plant environment.

The ideal soil mix for Collinsonia verticillata is well-draining and rich in organic matter. A blend with peat, perlite, and compost works effectively, providing balanced nutrients. Well-draining soil prevents water stagnation and encourages healthy root development, crucial for the plant's vigorous growth and resilience.