A melastome that's outgrown its pot tends to show it before you notice you should be looking. Water running straight through without the soil seeming to absorb any, roots visible at the drainage holes, or a plant that dries out noticeably faster than it used to are all signs it's time to size up.
When to repot
Spring, right as new growth is starting, is generally the least stressful time — the plant has the energy reserves to recover quickly. Avoid repotting during active flowering if you can help it; it's not usually fatal, but it can cause a plant to drop blooms it would otherwise have kept.
Sizing up correctly
One size up — roughly 2 inches larger in diameter — is generally enough. Jumping straight into a much larger pot leaves too much unused soil around the root ball, which holds excess moisture and raises the risk of root rot, undoing the benefit of repotting in the first place.
The process
- Water the plant a day or two beforehand — a well-hydrated root ball comes out of its pot far more cleanly than a dry one.
- Gently loosen the plant from its current pot, teasing apart any tightly circling roots at the outer edge rather than leaving them wound in place.
- Add fresh, well-draining mix to the new pot, position the plant at the same depth it was growing before, and fill in around the sides.
- Water thoroughly, then hold off on fertilizing for a couple of weeks to let the roots settle first.
For the right soil mix to use during this process, see our companion guide on soil and fertilizer for acid-loving melastomes.