Compassplant (Silphium laciniatum)

Also known as: Prairie Compass Plant, Polarplant, Cut-Leaf Silphium, Robinson's Compass Plant

Silphium laciniatum, often known as compass plant, is a perennial herb indigenous to North America. This plant, also called prairie compass plant, pilotweed, polarplant, gum weed, cut-leaf silphium, and turpentine plant, is frequently grown in gardens for its unique foliage and vibrant yellow blooms.

In This Article

Care Tips Water Sunlight Temperature Soil Fertilize Prune Propagation Repotting

Attributes of Compassplant

Lifespan

Perennial

Plant Type

Herb

Plant Height

91 cm to 1.8 m

Spread

1 m

Leaf Color

Green

Flower Size

2.5 cm to 15 cm

Flower Color

Yellow

Images of Compassplant

Quickly Identify Compassplant

Look for a tall, robust plant with deeply lobed leaves that often align north-south to minimize sun exposure. The flowers resemble sunflowers with bright yellow petals and can be up to several inches in diameter.

Scientific Classification of Compassplant

Phylum

Vascular plants

Class

Dicotyledons

Order

Asterales

Family

Daisy

Genus

Rosinweeds

Species

Compassplant

Planting and Growing of Compassplant

Care Difficulty

Easy

Watering Schedule

Every 3 days

Sunlight Requirements

Full sun

Sunshine Duration

6-10 hours

Ideal Temperature

60-80℉

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 Compassplant?

For Silphium laciniatum, also known as Compass Plant, the ideal watering amount is around 500 ml per session. This ensures that the water reaches deep into the root system but does not remain stagnant. The goal is to moisten the soil evenly while avoiding oversaturation that could lead to root rot.

What are the symptoms of an underwatered Compassplant? ›

What should I do if my Compassplant is not getting enough water? ›

What are the symptoms of an overwatered Compassplant? ›

How to save an overwatered Compassplant? ›

What Are the Sunlight Requirements for Compassplant?

Sunlight Requirements: Full sun

Duration of light: 6 to 8 hours daily

Silphium laciniatum ideally suits full sun environments, enduring 6 to 8 hours of sunshine daily. Ideal lighting ensures maximum photosynthesis rates, leading to better growth, healthier plants, and vibrant flowering, supporting garden biodiversity.

What amount of sunlight does Silphium laciniatum require? ›

How can I ensure Silphium laciniatum gets the ideal lighting? ›

What are the benefits of Silphium laciniatum receiving optimal sunlight? ›

More About Sunlight Requirements Techniques→

What Is the Ideal Temperature Range for Compassplant?

Ideal Temperature: 60 ~ 80℉

Silphium laciniatum thrives best within the temperature range of 60 to 80 degrees Fahrenheit. This range provides the ideal thermal conditions for its growth processes, including photosynthesis and nutrient uptake. Maintaining this range encourages robust stem and leaf development, as well as optimal flowering.

What Soil is Best for Compassplant?

Soil type: Loam, Sandy loam

Soil PH: 6.5 ~ 7.5

Silphium laciniatum thrives in soil with excellent drainage. Well-drained soil prevents root rot and other diseases, allowing the roots to access oxygen more effectively. This promotes healthy growth and vigor. While it needs well-drained soil, a balance with moisture retention helps Silphium laciniatum sustain growth during dry periods. Sandy loam offers this balance, ensuring efficient water absorption without waterlogging. This plant benefits from a substrate rich in organic matter. Such conditions supply essential nutrients for robust growth and contribute to the soil structure, enhancing water and nutrient absorption capabilities.

How to Fertilize Compassplant?

Fertilizer type: Balanced

For Silphium laciniatum, use a balanced fertilizer with equal parts nitrogen, phosphorus, and potassium. Apply 1/2 cup of granular fertilizer per plant during the growing season. Ensure the soil is lightly moist when applying to avoid root burn.

How to Prune Compassplant?

Pruning Time: Spring, Summer

Start by removing any dead, diseased, or damaged stems. This prevents the spread of disease and allows the plant to channel energy into healthy growth. Trim back excessively long stems to maintain a balanced shape. Use guided cuts to encourage attractive growth patterns, enhancing the plant's natural form. For more prolific blooming, prune faded flowers or flower stalks. This process, known as deadheading, ensures the plant focuses on producing new blossoms rather than seeding. More About Pruning Techniques→

How to Propagate Compassplant plant?

Propagate Time: Spring

Collect seeds from mature Silphium laciniatum plants during the late summer or early autumn when the seed heads have dried. Ensure that the seeds are fully developed and have a brownish color.

Silphium laciniatum seeds require a cold stratification period to break dormancy. Place the seeds in moist sand or sphagnum moss and store them in a refrigerator for at least 60 days.

Sow the stratified seeds in a prepared seed tray filled with a well-draining potting mix. Cover lightly with soil and keep the tray in a warm area with indirect sunlight until germination occurs.

More About Propagating Techniques→

How to Repot Compassplant plant?

Repotting frequency: Every 2-3 years

To determine when Silphium laciniatum needs repotting, observe for roots protruding from the drainage holes or sluggish growth. These are clear signals that the plant has outgrown its current home and requires a bigger pot.

When selecting a pot for Silphium laciniatum, ensure it is slightly larger than the current one with good drainage holes. A pot that’s too large can result in overwatering, while too small a pot will restrict growth.

Opt for a well-draining sandy loam. This soil type ensures good drainage, preventing root rot, while providing ample nutrients for optimal growth. Its texture promotes healthy root aeration, essential for a vibrant plant.