2026 Bonsai Care Calendar

January
January is typically our coldest month, with large temperature fluctuations. Later in the month, buds on deciduous trees will start to swell. Pines will slow down enough for repotting. The best time to repot is after bud swell on deciduous trees and just prior to the buds opening. Maples will wake up first. Anything we repot will need protection from wind and temperatures below 42°F for the first six weeks. Continue to monitor trees for water needs. Remember, the trees are resting, not dead.

February
Temperatures begin to warm up in February, with the average low around 32°F. Fluctuating temperatures mean trees are active whenever temperatures rise above 42°F, causing sap to flow. As a result, trees will take up more water. The vascular system begins releasing carbohydrates and sugars stored over winter, creating the energy needed for spring growth. Continue repotting deciduous trees. Repot scale junipers when the foliage color begins to change; repot needle junipers 2-4 weeks later. Toward the end of the month, you can start moving trees outside and into the sun. Place trees on the ground to protect from high winds. Ensure newly repotted trees and delicate foliage are protected from temperatures below 42°F.

March
March 15th marks the USDA Plant Hardiness date for the last hard freeze. This is typically our windiest month. Once deciduous leaves harden off, you can begin fertilizing them, along with your pines and junipers. Fertilize junipers when you see a color change in the foliage. For single-flush pines, begin fertilizing when temperatures reach the 60s, and start fertilizing multi-flush pines as well. If you plan to decandle or needle pluck a multi-flush pine, hold off fertilizing until May. Protect new, delicate foliage from temperatures above 80°F until they’ve hardened off. As the trees become more active, they will take up more water.

April
April 30th marks the USDA Plant Hardiness date for the last frost. Be vigilant for pests, as this is also a time when insects are most active. Allow trees (except refined Japanese maples) to leaf out, harden off, and re-accumulate energy. If you're looking for smaller leaves or more ramification, partially defoliate or cut leaves in half to let sunlight into the tree's interior. This doesn't apply to beech, hornbeams, or maples. Apply the second round of fertilizer.

May
May is our wettest month. Watch out for diseases, as the combination of heat and wet conditions creates ideal conditions for their spread. Once the foliage has hardened off and energy is reaccumulated, prune to remove the auxin from branch tips (except for beech, Korean hornbeam, and elms). This stimulates interior and lateral growth. All trees have emerged from winter dormancy and are rapidly growing. Continue fertilizing and monitoring water needs.

June
June is the best month for foliar development. Manage foliar growth, and protect delicate, deciduous leaves from full sun on the warmest days. Apply the final round of fertilizer early in the month before trees enter their summer dormancy. This is a great time for air layering and grafting.

July
By mid-July, trees will be well into their summer dormancy. They begin to drink less water, and fertilizer decomposes more slowly. Stop fertilizing until after the hottest part of summer passes. Avoid pruning foliage, as the tree needs all of its leaves to endure the summer heat. Just as we perspire to cool ourselves, trees rely on transpiration to cool down. 85-90% of water transpired by the foliage is the tree's effort to regulate temperature.

August
In August, trees are deep into summer dormancy. Be cautious with your watering technique—neither too wet nor too dry. Watch for spider mites, which thrive in hot, dry conditions. Avoid pruning foliage or fertilizing. This is essentially "put your scissors away" time.

September
As temperatures begin to drop in September, trees transition from summer dormancy into vascular growth. Wounds will begin to heal, and branches will start to fatten. Water uptake increases. Around mid-month, give trees their first fall application of fertilizer.

October
The USDA Plant Hardiness lists October 15th as the first frost date. Healthy bonsai can typically tolerate temperatures between 32-28°F at this point. Deciduous trees will show color changes in their leaves. Once the leaves have reached their peak color, stop fertilizing deciduous trees, as they’ve reabsorbed chlorophyll and won't be fully dormant for another 6-8 weeks. Water use will slow down by late October. Apply the second round of fertilizer to evergreens.

November
The first hard freeze date is around November 15th. Begin preparing trees for winter. Water use decreases, leaves are lost, and fertilizer no longer decomposes. The tree's priority shifts to storing energy in the vascular system for winter and spring. Place trees on the ground for protection and complete winter preparations. The more foliage, trunk, and root mass a tree has, the more cold-tolerant it will be. Apply the final fertilizer application to evergreens early in the month.

December
In December, deciduous trees use almost no water, and conifers need only minimal watering. Check trees 1-2 times a week for water. They are dormant, not dead, so continue to monitor water needs. Let the soil dry out a bit before watering. Always water 24 hours before a deep cold snap. Evergreen trees can tolerate temperatures between 0-15°F if they are on the ground and mulched. Deciduous trees, however, need protection from temperatures below 24°F. Early December is a good time to prune strong tips on Japanese Maples—leave two buds for bifurcation. If the internode is too long, prune it back to one bud. After spring leaves have hardened off, cut back to two buds and leave a 1/4" stub. For healthy Ponderosa and most pines, it’s a good time to remove third-year foliage, clean up the bottom, and refine the pads. The tree needs room to expel carbon dioxide.