Bonsai Care by Season

Note: The months are not a RULE, they are a GUIDE.

Why a Seasonal / Monthly Checklist Helps§

  1. Instant at-a-glance of major tasks each month/season.
  2. Helps you prioritize (e.g., "It's mid-spring—time to repot deciduous buds and watch for aphids").
  3. Combines the best of temperature triggers, zone details, and species specifics into a chronological flow.
  4. Encourages you to monitor changes (like lengthening days, night temps creeping down) so you adjust watering/feeding accordingly.
  5. The exact months vary by USDA zone, so each row might say "Jan/Feb (Zones 8–9)" vs. "Mar (Zone 5)" or "Apr (Zone 4)." But the structure remains the same—combine time of year + typical tasks + quick bullet points.

If you want a hyper-detailed version, you could break it down further (e.g., "April tasks" for zone 4 vs. zone 6). But even a broad seasonal approach, sorted by "cold/warm zone differences," keeps you on track. You can tailor it to your exact climate by shifting each group of tasks a few weeks earlier or later based on personal observation (e.g., some zone 5 folks do "April tasks" in May if spring is late).

Late Winter / Early Spring (Jan–Mar in Warmer Zones; Mar–Apr in Cooler Zones)§

  • General

    • Check for overwintering pests (scale eggs, spider mite eggs).
    • Apply dormant oil or lime–sulfur if trees are still leafless/dormant and you're within safe temperature limits.
    • Inspect for rodent damage (especially in cold zones) if stored in a garage or mulched outdoors.
    • Begin adjusting watering frequency upward as days get longer and temps rise.

  • Pines

    • Repot as buds swell (candle tips elongating but needles not yet opened), particularly if you see root-bound conditions.
    • Structural pruning (heavy cuts) while tree is still semi-dormant.
    • Start light feeding if in a warmer zone; wait until candles emerge in cooler zones.

  • Junipers

    • Repot as new shoot tips begin greening (still a cooler part of spring, not full flush).
    • Check for juniper scale or tip blight early—remove any dead tips.
    • Start mild fertilizer if days are consistently above 50 °F.

  • Deciduous

    • Repot when buds are swelling but not opened. Prime window for root work.
    • Heavy structural pruning is easiest now (can see the branch framework with no leaves).
    • If you want smaller leaves later, withhold strong fertilizer until after leaves open. (Light feed is okay.)

  • Tropicals

    • They may still be indoors in colder zones if nighttime temps <50 °F.
    • Check for spider mites or scale (common in winter indoors).
    • If you have a greenhouse and night temps stay ≥60 °F, you can begin more active feeding.

Mid to Late Spring (Mar–May in Warmer Zones; Apr–Jun in Cooler Zones)§

  • General

    • Watch for late frosts—cover or move vulnerable bonsai if needed.
    • Most species ramp up water intake—water daily (or more) as needed.
    • Address mild pest outbreaks early (aphids, early spider mites) with insecticidal soap or horticultural oil.

  • Pines

    • Candle-pinching on single-flush pines as new candles extend (aim to balance growth).
    • For Japanese Black/Red Pine, prepare for decandling if you do that, but not yet.
    • Increase feeding once candles are set.

  • Junipers

    • First strong flush—tip pruning once new shoots harden.
    • Good time for styling (wiring, initial shaping) if tree is healthy.
    • Fertilize regularly—junipers appreciate steady feeding in active growth.

  • Deciduous

    • Leaves are out and hardening; do your post-flush prune or partial defoliation (if practiced).
    • Begin a more robust feeding schedule.
    • Check for fungal leaf spots (especially if rainy/humid). Use copper or neem if needed.

  • Tropicals

    • In warmer zones, you can move them outdoors if nights >50–55 °F.
    • Repot once they're outside in stable warmth. Heavy pruning is well-tolerated if environment is warm/humid.
    • Start weekly feeding—they'll push new growth rapidly outside.

Early Summer (May–Jun in Warmer Zones; Jun–Jul in Cooler Zones)§

  • General

    • Hotter days → increase watering frequency, possibly 2× daily for small pots.
    • Early summer is prime time for some pest explosions (spider mites, aphids, scale crawlers).

  • Pines

    • Decandling window for multi-flush pines (e.g., JBP) typically starts mid-June in moderate zones. Warmer zones might do late June/early July.
    • After decandling, remove fertilizer for about 1–2 weeks, then resume.
    • If no decandling, just continue regular feeding and candle tip management.

  • Junipers

    • Second flush often emerges—prune again if shaping.
    • Watch for spider mites (common in hot, dry conditions).
    • Maintain moderate or slightly heavier feeding.

  • Deciduous

    • If defoliating certain species (maples, elms) for smaller leaves, do it early summer so it has time to re-leaf.
    • Fungus (powdery mildew, leaf spots) might rise in humid heat—apply fungicide if needed.
    • Keep up watering/fertilizing but watch for leaf scorch in extreme sun.

  • Tropicals

    • Peak growth outside in many zones—prune as often as needed (ficus can be trimmed multiple times).
    • Maintain weekly or biweekly feeding.
    • Check for mealybugs, scale, spider mites—apply insecticidal soap or systemic if you see issues.

Mid to Late Summer (Jun–Aug in Warmer Zones; Jul–Sep in Cooler Zones)§

  • General

    • Potential heat stress if temps >90 °F. Provide partial shade, extra watering, or midday misting.
    • Keep an eye on salt build-up from frequent fertilizing and watering—flush pots periodically.

  • Pines

    • If decandled, new needles start forming. Maintain moderate feed. Avoid heavy pruning—just remove any new buds you don't need.
    • If it's scorching hot, reduce stress by partial shading the pot (not necessarily the foliage).

  • Junipers

    • Third prune possible if growth is very vigorous.
    • Mites can flourish, so rinse foliage frequently.
    • Keep consistent feeding; watch for tip browning if dehydrated.

  • Deciduous

    • Late-summer pruning only if the tree is very strong—avoid pushing new tender growth too close to autumn.
    • Potential partial defoliation if you want a second flush for display, but only if the tree is healthy and you have enough warm weeks left.
    • Adjust fertilization (start reducing high nitrogen as you approach early fall).

  • Tropicals

    • Tropical "prime time"—they can handle frequent pruning/repotting if needed.
    • Mist or keep humidity up if it's super hot and dry.
    • If you see leaf yellowing, check for over-fertilizing or dryness.

Early Fall (Aug–Oct in Warmer Zones; Sep–Nov in Cooler Zones)§

  • General

    • Warmer zones might continue active growth; cooler zones see nights dropping below 50–60 °F, slowing some species.
    • Start transition for tropicals if nights approach 50 °F.

  • Pines

    • Ease off high-nitrogen feeds—switch to a more balanced or lower N feed.
    • Old needles might start to shed; normal if it's the inner, older sets.
    • Minimal pruning except removing dead or very long shoots.

  • Junipers

    • Possibly a light final prune if new tips formed in late summer.
    • Look out for scale crawlers in early fall. A systemic drench or horticultural oil might help.
    • Consider mild feed for root strengthening before winter.

  • Deciduous

    • If leaves are coloring/dropping, reduce fertilization.
    • Good time for early fall repot in some zones (especially 8–9) if you missed spring—only if you have at least 6 weeks before any frost.
    • Keep an eye out for pests like aphids or caterpillars on late growth.

  • Tropicals

    • Move indoors or to a greenhouse before nights <50 °F.
    • Inspect thoroughly for pests—treat if needed so you don't bring hitchhikers indoors.
    • Continue moderate feeding if they remain in warm conditions.

Late Fall / Early Winter (Oct–Dec in Warmer Zones; Nov–Jan in Cooler Zones)§

  • General

    • Cold zones: trees approach full dormancy. Start winter storage prep (mulching pots, unheated garage, etc.).
    • Warm zones: mild winter means some species never fully dormant.

  • Pines

    • In cold areas, keep them from frequent freeze-thaw cycles. <20 °F consistently can damage roots if unprotected.
    • No major pruning. Light tip cleanup if needed.
    • Some feed lightly in mild winters, but reduce or eliminate in very cold dormancy.

  • Junipers

    • Might develop a purplish/bronze winter color; normal.
    • Provide root insulation (mulch, bury pot) in sub-freezing climates.
    • Minimal watering needed—just don't let them dry out fully.

  • Deciduous

    • Fully leafless—store them in a suitable cold environment if zone is harsh.
    • Water sparingly (once every few weeks) if soil is cold/frozen.
    • No feeding—they're dormant.

  • Tropicals

    • Typically indoors or in a heated greenhouse.
    • Water less frequently if growth slows.
    • Check for indoor pests (spider mites, mealybugs) and maintain humidity (trays, misting).

← Back to Mastery Hub