Decandling aftercare – Bonsai Tonight

To restate a common theme – decandling is very stressful for pine bonsai. In some cases trees can lose up to 60% or 70% of their foliage during decandling. One-year old needles that have been growing beneath the shade of new shoots are newly exposed to full sun. Scores or even hundreds of small wounds have opened from which the trees have lost sap. It’s important to take care at this point to keep decandled pine bonsai healthy.

How do you care for trees after decandling?

Be kind to them. Freshly decandled pines are gathering their strength to send out new growth at this stage – growth that won’t be as strong as it was in spring.

• Watering – removing significant amounts of a tree’s foliage reduces transpiration and the tree’s need for water, however, decandling happens near summer solstice and even decandled trees can dry out quickly this time of year. As always, take care not to over or under water and reach for the hose before the soil completely dries out.
• Sunlight – keep decandled pines in full sun. Last year’s needles may yellow a bit but sunlight is necessary to help stimulate budding.
• Fertilizing – stop fertilizing when you decandle. If you use dry fertilizer, remove it when you remove the spring shoots. If you use liquid fertilizer, stop applying it when you decandle. After four weeks, begin fertilizing again following the same incremental approach used in spring. (See “Preparing trees for decandling” for details.) Exception – if your tree is on the weak side, continue fertilizing it throughout summer.

Decandled pine – 9 years old

Anything else?

Yes! Right after decandling is a good time to wire pine bonsai. Some restraint is required as the biggest cuts and bends are best performed when the tree is less active, typically in fall or early spring. When wiring pines after decandling it can be easy to break needles or injure recently cut areas so proceed with caution. And as new buds can begin to appear after just one week, the window of opportunity to wire is narrow. Wiring pines once summer shoots appear is possible but not advised as new growth breaks easily.

Not sure if this is the right time for you to wire? No problem, there’s no rush – feel free to wire in fall with the rest of us!