Repotting Planner: The Next Two Years
Turn root-bound signs and growth rate into a realistic repotting schedule, with pot sizes and soil volumes for each step.
Repotting is driven by roots, not by the calendar. Tell the planner what you can see and it estimates when the next pot-up is likely, how big to go and how much mix to buy.
Estimated next repot
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- Fresh mix to buy
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- New pot capacity
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A planning estimate, not a deadline. Check the root ball before you buy a pot, and repot in spring or early summer when the plant is growing.
How it works
The planner starts from a base interval for each growth rate, then shortens it for every root-bound sign you tick and for small pots, which fill with roots sooner. Large pots get a little extra time. The minimum interval is six months and the maximum is two years.
Each repot moves the plant up by 2 cm for slow growers, 4 cm for medium growers and 5 cm for fast growers, capped at 46 cm. The next interval is stretched by 15% because a bigger pot holds more mix and takes longer to fill.
Soil volume uses a cylinder: V = π × (d ÷ 2)² × (0.9d) ÷ 1000, in litres with the diameter in centimetres. The 0.9 factor leaves a small rim below the edge. The “fresh mix to buy” figure is 55–75% of that capacity, because the old root ball takes up space in the new pot.
Repot when roots are circling or the mix has broken down, not because a date arrived. A plant that is happy, stable and not root-bound can stay in its pot for years; a fast grower in a small pot may need moving twice in one season.
Frequently asked questions
How often should I repot a houseplant?
Only when the roots need it. Check for roots at the drainage holes, circling at the surface, water running straight through, or mix that has compacted and stopped holding moisture. A rough rhythm of every 12–24 months suits many foliage plants, but the root ball decides.
When is the best time to repot?
Spring and early summer, when the plant is actively growing and can rebuild roots. Avoid repotting in the dead of winter or while a plant is flowering unless there is a problem such as rot.
How much bigger should the new pot be?
Two to five centimetres wider in diameter. Going much larger leaves wet mix around a small root ball, which is a common route to root rot.
Can I repot a plant that is not root-bound?
Yes, but there is usually no need. If you want to refresh old mix, repot into the same size pot and trim the outer roots rather than upsizing.
Why does the planner show no repot in 24 months?
With a slow growth rate, few signs and a reasonably large pot, the model expects the roots to have room for a while. Check the root ball each spring and repot sooner if the signs appear.