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!
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.
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.
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.
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.
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 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!
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.
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.
Check your PSBA calendar to see who the guest artist is for September.
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.
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.
Pruning is not advised in December.
Inventory your tools and supplies so you can begin dropping hints
for holiday gift ideas!!