Compass Plant

silphium laciniatum

Also known as: ["Ozark compass plant","cutleaf rosinweed"]

Family: Asteraceae Genus: Silphium Category: Flowers

Overview

A tall, robust perennial native to North America, known for its deeply lobed leaves and large, yellow composite flowers that face upward.

Benefits & Perks

["long-flowering","wildlife attractant (bees, butterflies, birds)","drought tolerant","aesthetic foliage"]

Botanical Classification

Phylum: Magnoliophyta
Class: Magnoliopsida
Order: Asterales
Family: Asteraceae
Genus: Silphium
Botanical Name: Silphium laciniatum

Plant Characteristics

Basic Information
  • Category: Flowers
  • Suitable Location: open, sunny garden bed or meadow
  • Suitable For:
    Outdoor Landscapers Wildlife Supporters
  • Is Weed: No
  • Allergenicity: low
Environmental Needs
  • Climate: {"temperatureRange":"–30 to 40°C"}
  • Hardiness: {"zones":"4–9"}
  • Misting: rarely required, only if ambient humidity is very low
  • Drainage: Fast-draining; avoid waterlogged conditions.
  • Soil Type: Well-draining, loamy soil with organic matter; tolerates poor soils.
Maintenance Level
  • Maintenance Level: moderate
  • Toughness Level: high
  • Pruning Frequency: Annually in early spring; light pruning after flowering.
  • Pruning Intensity: Moderate; remove up to one-third of growth if needed.
Care Details

Ideal Sunlight Coverage:
Full sun (6–8 hours/day); tolerates partial shade but blooms best in direct light.

Sunlight Tolerance Tips:
Acclimate gradually to intense sun; protect from harsh midday sun in hot climates; ensure good air circulation.

Warning Signs: Yellowing leaves (overwatering); stunted growth (poor soil); root rot (poor drainage).

Care Requirements

Care Difficulty
moderate

moderate

Sunlight

full sun

Rotate plant for even light; use shade cloth in extreme heat; avoid north-facing windows indoors.

Watering

every 7–10 days during growing season, less frequently in dormant periods

Water thoroughly but infrequently; ensure soil dries between waterings; avoid overwatering.

Soil

well-drained, loamy soil with moderate organic matter

pH: Slightly acidic to neutral (pH 6.0–7.0).

Avoid heavy clay; amend with organic matter; ensure good drainage.

Temperature

Hardy in USDA zones 4–8; tolerates temperatures from -30°F to 90°F; prefers cool nights.

Protect from frost; avoid sudden temperature swings; maintain consistent soil moisture.

Fertilizing

every 4–6 weeks during active growth with balanced liquid fertilizer

Fertilize sparingly; avoid feeding during dormancy; water before and after application.

Propagation

Methods

Stem cuttings or division; seeds can be sown in fall or spring.

Step-by-Step Propagation Guide
  1. Take 4–6 inch cuttings.
  2. Remove lower leaves.
  3. Dip in hormone.
  4. Plant in medium.
  5. Maintain moisture.

Best Time: Early spring or late summer for cuttings; fall for seeds.

Environment

Warm (70–75°F), high humidity (70–80%), partial shade.

Medium

Perlite or sand mixed with peat; well-draining soilless mix.

Hormone

Optional, but rooting hormone can improve success rates.

Timeline

Roots in 3–6 weeks; establish in 1–2 months.

Tools Needed

Pruners, rooting hormone, pots, misting spray bottle.

Quick Tips

Use fresh cuttings; keep soil consistently moist; provide bottom heat if possible.

Pruning & Repotting

Pruning Guide
Method

Cut stems just above a leaf node or lateral branch; remove spent flower heads.

Pruning Plan

Remove dead or damaged stems; shape plant to encourage bushier growth; thin overcrowded areas.

Tools

Pruning shears, bypass cutters, gloves.

Checklist

Sterilize tools; prune dead/damaged growth; shape plant; clean up debris.

Repotting Guide
Best Season

Early spring before active growth begins.

Pot Size

Increase pot size by 2–3 inches in diameter.

Method

Remove plant gently; trim roots if crowded; use fresh soil mix; ensure drainage.

Suggestions

Repot every 2–3 years or when roots fill the container; beneficial for vigorous growth.

Checklist

Prepare new pot; trim roots; add fresh soil; water lightly; place in shade for a few days.

Advanced Care Tips

Watering Mastery
Watering Checklist

Check soil moisture; water deeply; ensure drainage; avoid wetting foliage.

How to Apply Water Properly

Water at the base of the plant, ensuring moisture reaches the root zone. Allow water to drain freely; water early in the day to minimize fungal risk.

Pro Tip: Use a soaker hose to deliver water directly to the roots, reducing evaporation and leaf wetness.
Watering Schedule Tips

Water deeply once every 1–2 weeks during active growth, reducing frequency in winter to once monthly. Adjust based on rainfall and soil dryness.

Soil Improvement

Add perlite or sand for drainage; incorporate compost for fertility; ensure good aeration.

Temperature Stress Management
Signs of Temperature Issues

Wilting, leaf scorch, stunted growth, or premature flowering in extreme heat; leaf drop or browning in cold stress.

Cold Stress

Slows growth; may cause root damage in poorly drained soil; foliage may turn yellow or brown.

Solution: Mulch heavily in fall; avoid overwatering; provide wind protection; use frost cloth if needed.

Hot Stress

Leaves may wilt, curl, or scorch; flowering may decline; growth may slow.

Solution: Provide afternoon shade; increase watering; use reflective mulch; ensure good air circulation.

Fertilizing Guide
Fertilizing Checklist

Use balanced fertilizer; apply in spring; avoid over-fertilization; water thoroughly after.

Fertilizing Method

Use a balanced, slow-release fertilizer in early spring; avoid high-nitrogen formulas; discontinue in late summer.

Common Problems & Solutions

Yellowing leaves in Silphium laciniatum may indicate nutrient deficiencies, overwatering, or pest infestations, affecting overall plant health.

Wilting in Silphium laciniatum can result from water stress, either due to drought or overwatering, impacting the plant's ability to perform photosynthesis.

Leaf spots on Silphium laciniatum may be caused by fungal or bacterial infections, leading to reduced photosynthetic efficiency and potential leaf drop.

Rotting, particularly root rot, can occur in Silphium laciniatum if the soil is excessively moist, leading to decay of root systems and eventual plant death.

Toxicity Warning

Cats
Slightly Toxic

Cats that ingest Silphium laciniatum may experience mild gastrointestinal discomfort. The toxic compounds in the roots and leaves can irritate the cat's stomach and intestines.

⚠️ Symptoms:
vomiting diarrhea depression
🌿 Toxic Parts:
roots leaves
⚡ Toxic If:

if eaten

Prevent cats from accessing Silphium laciniatum. Seek veterinary advice if ingestion is suspected.
Dogs
Slightly Toxic

In dogs, ingestion of Silphium laciniatum can lead to mild gastrointestinal upset. The compounds present in the roots and leaves may cause irritation to the dog's digestive system.

⚠️ Symptoms:
vomiting diarrhea lethargy
🌿 Toxic Parts:
roots leaves
⚡ Toxic If:

if eaten

Keep dogs away from Silphium laciniatum. If ingestion occurs, consult a veterinarian.
Humans
Slightly Toxic

Silphium laciniatum contains compounds that can cause mild gastrointestinal distress when ingested in significant quantities. The plant's roots and leaves are the primary sources of these compounds, which can irritate the digestive tract.

⚠️ Symptoms:
nausea vomiting diarrhea
🌿 Toxic Parts:
roots leaves
⚡ Toxic If:

if eaten

Avoid consumption of Silphium laciniatum. Keep away from children and pets.
Important: Keep this plant out of reach of children and pets. If ingestion occurs, contact poison control or veterinary services immediately.

Frequently Asked Questions

Q: Why is it called the Compass Plant?

A: The leaves of this plant often orient themselves in a north-south direction, historically used by settlers as a natural compass.

Q: Does it require full sun?

A: Yes, it thrives in full sun but can tolerate partial shade.

Q: Is it suitable for wildlife gardens?

A: Absolutely, it attracts bees, butterflies, and birds with its nectar-rich flowers.

Quick Reference
Family: Asteraceae
Care: moderate
Light: full sun
Water: every 7–10 days during growi
Suitable For: ["outdoor landscapers","wildlife supporters (attracts bees, butterflies, birds)"]
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