This guide to outdoor bonsai care is intended for use in the Pacific Northwest - specifically Western Washington. Recommendations in this guide may not be appropriate for other regions with different seasons. When in doubt, consult a trusted local bonsai advisor!

January:
This is the heart of winter, and while your trees are deep in dormancy, there is still work to be done. Continue your winter care by keeping your trees mulched and protected from freezing weather. Don't forget to check them as they do need watered from time to time, although their water needs will be minimal.

It's time for your second preventive spraying. Use horticultural dormant oil on your evergreens, but remember that dormant oil should not be applied when temperatures might be expected to drop below freezing before the spray has dried, because freezing causes the oil and water to separate, and the oil forms globules - good coverage is lost. Note also, that although oil and lime sulfur may be combined during the dormant season, oil and sulfur as separate applications should not precede or follow one another within 30 days. Avoid spraying those varieties with a blue-green cast to them, as the spray will green them up! For deciduous varieties only, mix a little lime-sulfur with your dormant oil spray. This is a good time to apply wire to some deciduous trees that break bud early, like larch, but be careful to not snap off the new buds as you wire. This also a good time to inventory your pots in order to give some thought to your repotting needs that are fast approaching. Give your pots a thorough cleaning so that when they are needed, they are clean and ready.

February:
Depending on your area, February can be the beginning of early spring. Frequently trees like Japanese larch can begin to bud out. If you need to repot, be sure to be vigilant about not letting your repotted trees freeze, since a cold snap can be just around the corner. You can begin to wire your deciduous trees while the buds are still small.

Get your tools ready by sharpening them up. Consider your soil needs for repotting and begin stocking the needed components. Sift your bark and grit. Get your hands dirty! You can begin to prune deciduous trees taking care to be sure that remaining branches and shoots are in good health. If in doubt as to whether buds on a particular branch or shoot are viable, then wait to prune until you see some bud-swell. Don't forget to sterilize your tools with alcohol before going on to another tree in order to avoid spreading diseases and / or pests.

Check your PSBA calendar to see who the guest artist is for February.

March:
Typically in Western Washington, your deciduous trees needing to be repotted that year will need to be completed before the end of the month. Look to your trees for signs that they are wakening. Look for swelling buds and white growing tips at the end of your roots. Those deciduous trees that you were unsure about pruning can probably be safely pruned. Seal all substantial cuts with paste and protect them from heavy frost. Avoid repotting any larch that are showing green. If they are showing green, it is best to wait until next year.

Generally there is no need to begin fertilizing your trees yet. Let them leaf out, and for your repotted trees, begin your feeding regime at least one month after repotting. You may want to keep them sheltered under the eaves of the house and out of cold winds.

Check your PSBA Calendar to see what is going on at the monthly meeting.

April:
If you haven't repotted your deciduous trees by now, it might be best to wait until next year. However, junipers are OK to do now, and pines can be started any time during the month. Continue to provide good after care, by protecting repotted trees from frosts. You can begin fertilizing trees repotted in March. Keep your initial fertilizer mix on the light side for those first couple doses of fertilizer.

Continue to watch for insects, especially aphids on crabapples, maples, etc. As the weather warms you will need to step up your watering routine some.

Check your PSBA calendar to see who the April guest artist will be! Start "sprucing" up a tree or two for the annual Spring Show in May.

May:
Wrap up any repotting of pines by early in the month. Remember to keep them in the shade for a couple weeks. Trees repotted in April can be given their first light doses of fertilizer.

Continue to patrol for insects and adjust your watering to match the warmer weather. Candles on pines can be pinched any time. Start with the weak buds and do the strong buds a week or so later. Spruce, junipers and larch shoots are probably ready for their first pinching of the season. Watch the new growth on your deciduous trees and trim back to 1-2 pairs of leaves. It is critical to stay on top of maples now and pinch out that center bud just as it emerges from the middle of the first two leaves. Continue feeding your trees on a regular basis.

Don't forget to attend the Spring Show. We need your help so please contact the chair to volunteer to docent or work the registration or consignment tables.

June:
Things are growing like crazy now. Deciduous trees will need regular trimming. Be sure to sterilize your tools as you move from tree to tree. Two needle pines that are being encouraged to back bud should have new growth removed by mid month. Do this only with strong trees. If the tree is weak or certain branches are weak, then it is best to get the tree or branches healthy before removing all of this year's growth.

June is a good time to leaf prune deciduous trees like maples or elms. This should be done only on strong trees that have been fertilized well. On maples, be sure to leave most of the petiole.

Pests are in full swing now, so use due vigilance. Spray as needed. June is a time when many trees suffer wire scars so be sure to pay good attention to the trees on which you have wire. Pay special attention to deciduous trees and to the wire on the outside bend of branches. Continue with your fertilizing routine.

Call a fellow bonsai buddy and offer to water / care for his or her trees when your friend is on vacation this summer!

July:
Summer is in full swing now so watch your watering daily, especially small trees like mame and / or shohin. Trees that are sensitive to full sun, like Japanese maples, should be situated so they are at least partially shaded from hot afternoon sun. Continue to check your wires.

On black pines from which you removed this year's growth, you should start to see new buds forming. Be careful of these new buds if you are adding or removing wire, since they are the future branches. Some trees, like pines & hemlocks enjoy a couple mild doses of fertilizer during late summer and early fall.

Don't forget to attend the PSBA summer potluck and sale.

August:
In the Pacific NW, August can be our hottest month so pay careful attention to your watering and continue to protect trees that are sensitive to the hot sun, (if we get any!) It is recommended that you start tapering off nitrogen late in the month and go to something like 0-10-10 in late Sept,-mid October. Avoid doing any heavy pruning so as to not generate new growth that will not harden off before frosts in the fall.

It is too late to do any leaf pruning and avoid doing air layers this late in the summer. This is not such a good time to wire deciduous trees. It is hard to see the branching with all the leaves. However, pines and junipers can still be wired if needed.

Late August is a good time to begin applying 0-10-10 to help harden off twigs and roots, and help set buds for flowering varieties.

September:
Early in the month can still be warm so watch your watering and don't let your trees dry out too much. Growth is really slowing now. Continue with your 0-10-10 fertilizers. Avoid pruning any trees except pines. Jin and shari can still be worked, but avoid heavy cuts on deciduous trees until next spring. Continue to watch your wiring, especially on pines. Pines tend to put on their wood in the fall so watch closely to avoid wire scars.

Check your PSBA calendar to see who the guest artist is for September.

October:
Fall is here. This is a good time to remove wire that is not intended to stay on throughout the winter. Give your trees their last doses of 0-10-10 for the year. Watering needs are diminishing now, so be careful to not over water. Fall color should be beginning show on some of your deciduous trees.

Start watching the weather forecast and be prepared to protect those trees that might be damaged by a heavy freeze. Any trees that were repotted in the fall should be carefully protected from freezing for the winter. Don't bring them into the heated house, but do not allow them to freeze either!

Check your PSBA calendar to see who the guest artist is for October.

November:
Fall color should be at its peak early in the month. During November we typically get our first freezes so be prepared to protect your trees. November can also bring long rainy spells so shelter those trees that are sensitive to excess rain, such as pines.

Once the leaves have dropped from your deciduous trees is a good time to begin needle thinning your two needle pines. If you thin last year's needles by pulling be careful to pull in the direction they grow. Otherwise, you will most likely lose the bud you are trying to stimulate. On strong, well developed pines, you can also thin this year's needles by thinning to 5 or 6 pairs of needles in the top half of the trees and 7 or 8 pairs in the lower half of the trees.

Don't forget to clean dropped leaves off your soil surfaces since they can provide shelter for unwanted pests. If you put your trees away for the winter be sure to inspect them for pests like mealy bugs or scale before doing so.

The PSBA annual meeting happens in November. Go cast your vote and volunteer for a service position for the year. Also check your PSBA activity calendar to see who the guest artist is for the month.

December:
Winter is here, complete with steady rain and the potential for sub-freezing weather. Before putting your trees away for the winter it is a good time to give them their first spray of dormant oil. For deciduous trees you can add lime-sulfur as well - follow the label instructions. (See precautions in the January listing.) Also, be sure to clean any dead leaves away from the tops of the pots.

Pruning is not advised in December. Inventory your tools and supplies so you can begin dropping hints for holiday gift ideas!!