An Oft-Forgotten Repotting Clue-

Deciding to repot or not is often fraught with angst. Do we do it this year? Maybe next year?

Considering the clues can help you decide. Maybe you know a tree with slow water penetration, that one might be ready for a repot. Try driving a chopstick into the soil on another one, near the edge of the pot—if it goes in easily, likely you can skip it this year. Perhaps a few branches died on the next tree…maybe you want to repot it to investigate.

One clue that doesn’t get much attention is internode length.

Azaleas are among the easiest to see a change in internode length over a few years. Azaleas grow long internodes after repotting, showing off their colt energy. Then after a couple years the internodes moderate. And then there’s a year when they are really quite short, the twilight period. The year after that, some branchlets might die, or worse, the crown.

This azalea shows happy, fairly long shoots. It’s unlikely that it needs repotting this spring.

An azalea with short internodes…might be a clue to repot. And yet check in with other clues as well.

While the chopstick thrust into the soil is likely your best tool to determine when to repot, notice all the clues. Weakening. Branch loss. Poor drainage. And also short internodes. When we line up two or more of these clues, our confidence in repotting timing can strengthen.

February 2021 Bulletin Board:

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  1. Lars Grimm says:

    Thanks for the great info Michael. Can you clarify the chopstick thrust into the soil technique?

  2. Steve Young says:

    Good to know.

  3. literati says:

    Michael, thanks for the clues. Now I will remember the internodes, and of course other ones.

  4. David M Schleser says:

    Any suggestions for preventing these lengthened internodes on newly repotted deciduous trees and increase in needle length on pines?

  5. John Wiessinger says:

    Really appreciated your tip on azalea internodes and repotting. I plan to go right out to my garage and check. Thanks so much for sharing.

  6. Skipp Serrano says:

    Thanks for the tips. I was wondering how I’d know. Now I do.

  7. Thomas G says:

    Question, a bit off topic, but still in the repotting “universe.” I’ve heard you talk about your “on the way” or “growing on” trees you don’t use the standard bonsai soils, but you are growing these trees in more of an organic or nursery-type soil mix. Care to share your usual soli mix for growing out maples and other deciduous trees of that nature?

    • crataegus says:

      Sure, for the younger stock we work with that grow in large nursery flats or containers I usually use 80% pumice, and 20% of a bark/steer mix. You could use less pumice, though pines might not be as happy in that over the long term. Although this gives really strong growth, it needs piecemeal exchange for the volcanic media we use in the transition to a bonsai pot.

  8. jjmistretta says:

    An old professor of mine said, “The more you know the less able you are to make a definitive statement about anything.” Now with this fact I can go back to banging my forehead against the wall because up until now short internodes,to me, used to mean that ramification efforts were working. Now there is something else I know to spook me when I see them. How to know the difference what short internodes are telling me. What would life be without angst. Any thoughts?

    • crataegus says:

      You’re correct, your ramification efforts are working! The thing is, eventually our efforts end up slaughtering a few unless we repot the tree to refresh it and reinvigorate the system. Also more fertilizer helps, as bifurcations mount. But life without angst is for non-German speakers, perhaps?

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