Today's bonsai blog post, When is best to repot? Do we repot them all at once? is taken directly from Michael Hagedorn's Crataegus Bonsai blog.

All the text in italics is directly quoted from Michael and all the photos are his.

Bud swell on Hemlock, about right repotting timing

Ponderosa Pine—a bit late

When is best to repot? Do we repot them all at once?

The general guideline to repot as they break bud is a good one. Some, like pines, though, are best repotted a bit before we see bud elongation. Maples, as buds open.

If you have a long spring—one that goes on at a mild temperature for a couple months or more—then the schedule separates into phases.

Black Pine—much too late

Ezo Spruce—the tree on the right, correct repotting timing; tree on the left, too late. Tricky for this specimen as it is a forest…try to gauge by the first tree to begin moving.

A long spring schedule might look like this:

Deciduous first: Quince (Japanese and Chinese), Trident
Then, Black Pines
Satsuki, as they green up
Single flush pines, like Japanese White and Ponderosa
Spruce
Then more deciduous, like Japanese Maples, Elm
Hinoki
Beech, Hemlock
And finally, Juniper

Beech—a hair early. Beech are tricky. They are late openers, usually almost overnight. Ideally, wait for a bit of green between the bud scales to show, then repot.

Vine Maple—like many maples, they can be repotted a bit “long in the tooth”, when the buds are swelling and opening

Though Maple can be repotted with buds opening, once leaves are out it’s on the late side

If your spring is short, just a month, trees may be repotted roughly at the same time.

If repotted outside its ideal window—before or well after bud break—place the tree in shelter, preferably a greenhouse for several weeks. Greenhousing any repotted plant is a good practice for protection from wind, frost and too much rain. A common mistake is placement in too much shade after repotting. Plants need light to grow roots, and in many locations the spring sun is mild.

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