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With most houseplants, moving up a pot size each spring is good practice. With this one it is the main reason people never see a flower. A crowded root ball is one of the conditions that pushes the plant from making leaves to making flowers, and every repot resets that.
So the default answer is to leave it. Repot every three to four years, or when the plant physically cannot carry on, and top dress in the years between instead.
| Situation | Repot or not | Reason |
|---|---|---|
| Roots circling the surface, plant still growing well | Leave it | This is the state you want it in |
| Roots pushing the plant up out of the pot | Repot | It can no longer hold water at all |
| Pot cracked or bulging from root pressure | Repot | The roots are stronger than the pot |
| Water runs straight through in seconds | Repot | There is more root than mix left |
| Mix stays wet for over a week in summer | Repot | The mix has broken down and gone airless |
| Just bought, in a plastic nursery pot | Repot once, then leave it | Move it into something heavy enough not to topple |
A plant that has just flowered, or that has a bud forming, should never be repotted. Wait until flowering has finished completely, then wait until the following spring.
Timing and pot choice
Repot in spring as growth restarts, so the plant has the whole warm season to rebuild roots. A plant repotted in autumn goes into the cool months with damaged roots in fresh wet mix, which is the worst combination there is.
- Go up one size only Two inches (5 cm) more diameter, no more. A large pot around a small root ball holds wet mix the roots never reach, and that mix sours.
- Choose weight over looks A tall plant in a light plastic pot blows over outdoors and snaps leaf stalks. Terracotta or a heavy glazed pot, or drop the plastic pot inside a heavy outer one.
- Demand real drainage Several large holes, and a pot that stands clear of its saucer. Blocked drainage undoes every other good decision on this page.
- Deep rather than wide The fleshy roots go down. A deep pot suits the plant better than a shallow bowl of the same volume, and it is far more stable.
A mix that drains
The plant is not fussy about what it grows in as long as water leaves quickly and there is some weight to it. Straight peat based houseplant compost holds too much water and is too light for a tall plant, so it needs opening up and ballasting.
| Component | Proportion | What it does |
|---|---|---|
| Soil based potting mix | Two parts | Weight, stability and nutrient holding |
| Coarse bark or coir chips | One part | Air spaces that survive several years |
| Coarse grit or perlite | One part | Drainage and, with grit, extra ballast |
Do not add crocks or gravel in the bottom of the pot. They do not improve drainage and they raise the wet layer higher into the root ball. Use the space for mix instead.
Doing it without wrecking the roots
The thick roots snap easily and each broken end is a way in for rot. Handle the root ball as one solid object and disturb it as little as you can get away with.
- Water it the day before A moist root ball slides out in one piece. A bone dry one crumbles and takes roots with it.
- Free it from the sides Run a long knife round the inside of the pot, then lay the pot on its side and pull the plant out by the base of the stalks, not by a single stalk. Cut a plastic pot away rather than fight it.
- Tease, do not tear Loosen only the outer half inch of circling roots with your fingers. Leave the core of the root ball intact. This is not a plant that wants its roots washed clean.
- Cut out anything rotten Brown, soft roots that slide their outer skin off are dead. Cut them back to firm tissue with a clean blade and let the cuts dry for an hour before potting.
- Pot at the same depth Set the crown at exactly the height it was before. Burying the base of the fans deeper rots them, and planting high dries them out.
- Firm and water once Work the mix down the sides with your fingers, water once thoroughly to settle it, then keep it on the dry side for two weeks while the cut roots heal.
Do not feed for six to eight weeks after repotting. Fresh mix carries enough, and fertilizer on damaged roots burns them.
Top dressing in the years between
In the three years you are deliberately not repotting, the plant still needs its mix refreshed. Top dressing does that without touching the roots, and takes ten minutes each spring.
- Scrape off the top Remove the top two inches (5 cm) of old mix, taking any white salt crust and moss with it. Stop as soon as you meet roots.
- Replace with fresh mix Add fresh mix of the same recipe and firm it lightly. Mix in slow release fertilizer at the rate on the packet while you do it.
- Flush the pot afterwards Water slowly and thoroughly so it drains freely away, which clears salts that have built up deeper in the pot.
Keep a record of the pot
Write down the date of every repot, the pot size you moved into and what mix you used. With a plant repotted only every three or four years, memory is not going to serve you, and the interval since the last repot is one of the few real levers you have over flowering.
Note the number of fans at the same time. Comparing fan count against repot dates over several years shows you plainly whether leaving it crowded is doing what it is supposed to do in your conditions.