Acanthus-leaved Jerusalem Sage
phlomis tuberosa
Also known as: ["Acanthus-leaved Sage","Tuberous Jerusalem Sage"]
Overview
A hardy perennial with tuberous roots and large, lobed leaves, producing tall spikes of lavender-purple flowers in summer.
Benefits & Perks
["long-flowering","deer resistant","wildlife attractant (bees, butterflies, birds)","drought tolerant","low maintenance"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Lamiales |
| Family: | Lamiaceae |
| Genus: | Phlomis |
| Botanical Name: | Phlomis tuberosa |
Plant Characteristics
Basic Information
- Category: Flowers
- Suitable Location: border or perennial garden, prefers open spaces
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"–10–35°C"}
- Hardiness: {"zones":"4–9"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Fast-draining to prevent root rot.
- Soil Type: Well-draining, loamy soil with added organic matter.
Maintenance Level
- Maintenance Level: low
- Toughness Level: high
- Pruning Frequency: After flowering in summer; light pruning in early spring to remove dead or damaged stems.
- Pruning Intensity: Moderate; remove up to one-third of old growth if needed.
Care Details
Ideal Sunlight Coverage:
Full sun (6–8 hours of direct sunlight daily). Tolerates partial shade but may produce fewer flowers.
Sunlight Tolerance Tips:
Acclimate plants gradually if moving from shade to sun; protect from intense midday sun in hot climates; ensure good air circulation to prevent fungal issues.
Care Requirements
Care Difficulty
easymoderate
Sunlight
full sun to partial shade
Rotate plant for even growth; use shade cloth in extreme heat; avoid placing in drafty areas.
Watering
every 7–10 days during active growth, reduce in winter
Water thoroughly but infrequently to encourage deep root growth; ensure soil dries slightly between waterings; avoid overwatering, especially in winter.
Soil
well-drained, moderately fertile soil
pH: Slightly alkaline to neutral (pH 6.5–7.5).
Avoid heavy clay soils; ensure good aeration; amend with organic matter for better structure.
Temperature
Hardy in USDA zones 4–9. Prefers temperatures between 60–75°F (15–24°C) during active growth; tolerates winter lows to -20°F (-29°C).
Protect from frost in early spring; avoid placing in drafty areas; adjust watering in extreme heat or cold.
Fertilizing
every 4–6 weeks during spring and summer
Avoid high-nitrogen fertilizers to prevent excessive foliage at the expense of flowers; fertilize sparingly in winter.
Propagation
Methods
Stem cuttings or division of tubers. Stem cuttings are more common for home growers.
Step-by-Step Propagation Guide
- Take 4–6 inch cuttings.
- Remove lower leaves.
- Dip in rooting hormone.
- Plant in medium.
- Maintain humidity.
- Transplant when rooted.
Best Time: Early spring or late summer when the plant is actively growing.
Environment
Warm (65–75°F), high humidity (70–80%), and bright indirect light.
Medium
Well-draining mix of perlite and peat moss or cactus mix.
Hormone
Recommended to promote root development.
Timeline
Stem cuttings may root in 4–6 weeks; division can yield quicker establishment.
Tools Needed
Pruning shears, rooting hormone, small pots, misting spray bottle.
Quick Tips
Use sterile tools to prevent disease; maintain consistent moisture; provide bottom heat for faster rooting.
Pruning & Repotting
Pruning Guide
Method
Deadhead spent flowers; cut back leggy stems to promote branching; remove any dead or crossing branches.
Pruning Plan
Prune to maintain shape, encourage bushier growth, and remove spent flower stalks for continuous blooming.
Tools
Pruning shears, bypass cutters, gloves.
Checklist
Sterilize tools; prune after flowering; cut just above a leaf node; remove dead or diseased growth.
Repotting Guide
Best Season
Early spring before new growth begins.
Pot Size
One size up from current pot; ensure adequate drainage holes.
Method
Gently remove the plant; trim any dead roots; place in a slightly larger pot with fresh, well-draining soil; water thoroughly.
Suggestions
Repot every 2–3 years or when the plant becomes root-bound. Necessary to refresh soil and accommodate tuberous roots.
Checklist
Choose appropriate pot size; use fresh soil mix; handle roots carefully; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture before watering; water deeply at the base; ensure proper drainage; adjust frequency seasonally.
How to Apply Water Properly
Water directly at the base of the plant, ensuring moisture reaches the root zone. Water until it drains from the bottom, but avoid waterlogging. Water in the morning to minimize evaporation and fungal issues.
Watering Schedule Tips
Water deeply once per week during active growth, reducing frequency to every 2–3 weeks in winter. Adjust based on rainfall and soil moisture retention.
Soil Improvement
Add perlite or coarse sand for drainage; incorporate compost for fertility; ensure soil is not compacted.
Temperature Stress Management
Signs of Temperature Issues
Chlorosis or leaf scorch in excessive heat; stunted growth or bud drop in cold stress; wilting in extreme conditions.
Cold Stress
Low temperatures can slow growth or cause dieback, but established plants are generally cold-hardy due to their tuberous roots.
Solution: Mulch heavily around the base in winter; protect from harsh winds; avoid overwatering, as cold, wet soil exacerbates stress.
Hot Stress
Excessive heat can lead to leaf scorch, reduced flowering, and wilting, especially if combined with drought.
Solution: Provide afternoon shade in extreme heat; water deeply and mulch to retain soil moisture; ensure good air circulation.
Fertilizing Guide
Fertilizing Checklist
Use balanced fertilizer; apply in early spring; dilute liquid fertilizer for monthly feedings; stop in late fall.
Fertilizing Method
Use a balanced, slow-release fertilizer in early spring. Apply a diluted liquid fertilizer monthly during active growth, avoiding winter.
Common Problems & Solutions
Toxicity Warning
Cats
Non-toxicPhlomis tuberosa is not known to be toxic to cats. There are no documented cases of adverse effects from ingestion of this plant by felines.
⚡ Toxic If:
if eaten
Dogs
Non-toxicPhlomis tuberosa is not known to be toxic to dogs. There are no documented cases of adverse effects from ingestion of this plant by canines.
⚡ Toxic If:
if eaten
Humans
Non-toxicPhlomis tuberosa is generally considered non-toxic to humans. There are no known toxic compounds or physiological effects associated with this plant when ingested in typical amounts.
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: How tall does Phlomis tuberosa grow?
A: It typically reaches 3–4 feet in height.
Q: Does it require full sun?
A: Yes, it thrives in full sun but can tolerate partial shade.
Q: Is it suitable for dry climates?
A: Yes, it is drought-tolerant once established.
Quick Reference
| Family: | Lamiaceae |
| Care: | easy |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
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