Acer macrophyllum
Big Leaf Maple
Large-leafed native maple, slower to ramify; best in larger sizes or naturalistic styles.
DeciduousBroadleaf
Now: Mid Spring
- watering
- Maintain even moisture; soil warms—might need daily watering in pots.
- fertilization
- Feed every 2–3 weeks with balanced bonsai fertilizer.
- bud shoot management
- Trim long shoots after first flush to promote ramification.
- pests disease
- Monitor for caterpillars and scale insects.
Care Guide
Placement
Full sun
Hardy species; prefers consistent sunlight.
Watering
Moderate
Avoid waterlogging; prefers well-drained soil.
Fertilization
Balanced
Feed monthly in growing season; reduce in late summer.
Pruning
Structural in early spring, maintenance through summer
Hard prune before bud break to shape.
Wiring
Spring or Autumn
Branches are brittle; wire when flexible.
Repotting
Every 2-3 years
Use coarse mix; avoid overpotting.
Propagation
Cuttings or seed
Seedling development takes time but worthwhile.
Winter: Fully hardy but mulch roots in extreme cold.
Summer: Water deeply and regularly in hot weather.
Zone 8b: Protect roots if temps < 20 F
Seasonal Calendar
Late Dormancy02-15 — 03-10
- watering
- Keep soil lightly moist to prevent desiccation during root activation.
- pruning
- Perform final structural cuts before bud swell; avoid heavy pruning.
- wiring
- Safe to wire before buds open, but wood is brittle—use caution.
- pests disease
- Clear debris to reduce overwintering pests.
- winter protection
- Provide root insulation; watch for late freezes.
- wound management
- Seal larger pruning cuts to reduce cold damage.
Early Spring03-11 — 04-15
- watering
- Gradually increase; encourage steady moisture as buds swell.
- fertilization
- Begin light feeding with balanced 10‑10‑10 formula post-leafing.
- repotting
- Repot window opens just before leaf burst; root prune carefully.
- pruning
- Trim new buds lightly to refine structure.
- wiring
- Apply or adjust wiring while cambium is active.
- bud shoot management
- Pinch long shoots to encourage back-budding.
- pests disease
- Scout for aphids; treat organically if seen.
- propagation
- Softwood cuttings may be rooted at this time.
- development
- Allow trunk base to thicken by limiting aggressive top pruning.
Mid Spring04-16 — 05-10Now
- watering
- Maintain even moisture; soil warms—might need daily watering in pots.
- fertilization
- Feed every 2–3 weeks with balanced bonsai fertilizer.
- bud shoot management
- Trim long shoots after first flush to promote ramification.
- pests disease
- Monitor for caterpillars and scale insects.
Late Spring05-11 — 05-31
- watering
- Increase frequency based on warming temperatures.
- fertilization
- Switch to higher nitrogen (e.g., 12‑6‑6) if tree is vigorous.
- pests disease
- Leaf-chewing pests may emerge—treat promptly.
Early Summer06-01 — 06-30
- watering
- Deep water regularly—pots warm up quickly in heat.
- fertilization
- Continue balanced feed every 2 weeks.
- pruning
- If leaf size becomes excessive, consider partial defoliation.
- wiring
- Minor wiring for refinement before tissue hardens.
- defoliation
- Partial defoliation after first flush can reduce leaf size.
- pests disease
- Watch for mites; treat with horticultural oil if needed.
- summer protection
- Provide afternoon shade during heatwaves.
Mid Summer07-01 — 08-10
- watering
- Monitor daily; ensure no drought stress.
- fertilization
- Taper nitrogen; hold feed during hottest weeks.
- pruning
- Pinch back soft spring growth; wait until fall for structure.
- pests disease
- Check for powdery mildew in humid weather.
- summer protection
- Ensure root ball doesn’t overheat—shade or pot insulation.
Late Summer08-11 — 08-31
- watering
- Maintain consistent moisture as growth slows.
- fertilization
- Apply phosphorus high feed to support root health.
Early Fall09-01 — 09-30
- watering
- Gradually reduce watering frequency.
- fertilization
- Final feed of the season to build winter reserves.
- pruning
- Structural wiring/pruning before leaf color onset.
- wiring
- Optimal time for wiring with active sap.
- development
- Encourage hardening of summer growth.
Mid Fall10-01 — 10-31
- watering
- Reduce watering as foliage falls.
Late Fall11-01 — 11-15
- watering
- Water sparingly; avoid soggy pots in cool temps.
- winter protection
- Begin root insulation; move pots to sheltered area.
Early Winter11-16 — 12-31
- watering
- Minimal watering only during dry periods.
- winter protection
- Keep protected from frost; mulched pots preferred.
Mid Winter01-01 — 01-31
- watering
- Check moisture monthly; prevent dehydration.
- pests disease
- Scan for winter insect eggs or scale.
- winter protection
- Ensure root insulation through coldest weeks.
Late Winter02-01 — 02-14
- watering
- Resume regular watering as buds begin swelling.
- repotting
- Begin planning for spring repot; prep soil and tools.
