Deciduous Trees – December marks the true beginning of dormancy for basically all deciduous species in Northeast Florida. By now, most trees have fully dropped their leaves or are in the final stages of doing so, giving you the clearest view of branch structure all year. This is a good month to study your trees’ silhouettes, take notes for late-winter structural pruning, and evaluate any wiring that may need adjusting or removal before growth resumes in spring. Our daytime highs have typically ranged from the upper 50s to upper 60s, with nights commonly falling into the 40s and occasionally dipping into the 30s during cold fronts. Your trees won’t need much water, so reduce frequency significantly—but don’t let them dry out completely. Keep an eye on soil moisture and avoid fertilizing this month. Deciduous species appreciate the chill, but be prepared to offer brief protection if temperatures drop near or below freezing to smaller trees in bonsai pots as they are less insulated from outside temps. This is also a great time to start identifying which trees you are planning to repot closer to the end of winter and getting prepared to do so. Conifers and Broadleaf Evergreen Trees – Conifers and broadleaf evergreens are generally stable and comfortable during our mild Jacksonville winters, but growth is noticeably slowed. December is a good maintenance month: monitor for pests, remove old needles as needed, or begin applying some of those tips and techniques we learned from David Ruth at November’s meeting! Broadleaf evergreens like olives, boxwoods, yaupon, and podocarpus will remain active but slow, so adjust watering accordingly and be prepared to provide these trees with some protection (as needed) if temperatures do go below freezing. With cooler daytime temperatures and cold nights, overwatering becomes the most common mistake. Make sure your soil drains well and stays on the slightly drier side between waterings. Be mindful of unexpected cold snaps; while most hardy species tolerate the mid-30s, tender evergreens or recently worked trees may need to be pulled into a protected area for the coldest nights. Tropical Trees – December is one of the highest-risk months for tropical bonsai in Northeast Florida. Sustained warmth is no longer reliable, and nighttime lows frequently dip into the upper 30s–40s. Any forecast near 45°F or below means your tropicals—such as ficus, bougainvillea, jaboticaba, schefflera, and dwarf jade—should come indoors or into an enclosed, warmed space (ideally a greenhouse). Trees like Buttonwood or Brazilian Rain Trees are even more sensitive and arrangements should be made so that they do not experience sustained temperatures below 55°F for best results. At this point in the year, tropicals should already have their winter housing established. If not, now is the time to commit to a plan: greenhouse, grow tent, garage with supplemental light, sunroom, or even a bright indoor window. Growth will be minimal, so reduce watering significantly and avoid fertilizing. Check regularly for scale, mealybugs, and whitefly, which thrive in warm indoor environments. Proper airflow and clean leaves help prevent these issues. Miscellaneous – December is a “stay ready” month for bonsai winter care in Jacksonville. Our winters are mild overall, but sharp temperature swings can arrive with little warning. Keep a close eye on the weather—especially for sudden freezes or back-to-back cold nights. A few reminders for this month: - Have frost cloths, blankets, or covers ready for emergency protection (never allow covers to touch foliage directly during a freeze).
- Avoid repotting—true repotting season begins much later, in late winter.
- Trim watering schedules across all species; root zones stay cooler and wetter now.
- Do not fertilize most trees, except perhaps very lightly with low-nitrogen formulas for evergreens if needed.
- Check wiring weekly, as bark can become brittle in cold weather.
- Keep benches clean and remove debris to discourage overwintering pests.Staying prepared, flexible, and attentive will help your trees sail smoothly through our fluctuating December weather and set the stage for healthy spring growth.
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