Gadenin日本語Get the appIt likes being a little tight
Chinese evergreen is not a plant that wants a bigger pot every spring. It grows and colors better when the roots are moderately confined, and moving it up too often gives you a large pot of wet compost, slow growth and eventual root rot. Two to three years between repottings suits most plants, and a mature one in a large pot can go four or five if you top dress it.
The reason a slightly tight pot works is drainage. Roots fill the compost, take up the water quickly and let air back into the mix between waterings. A large volume of rootless compost never does that, and it is the wet dead zone at the bottom of an oversized pot where rot begins.
- Water runs straight through Water appears at the bottom within a couple of seconds and the compost hardly wets. The roots have filled the pot and the water is running down channels rather than soaking in.
- Roots at the drainage holes Pale roots pushing out of the bottom, or a solid disc of root when you lift the plant out, means it has run out of room. This is the clearest signal there is.
- New leaves are getting smaller If the light has not changed and you have been feeding, each new leaf coming through smaller than the last means the roots cannot supply the top.
- It dries out in two or three days A plant that suddenly needs water twice a week in spring when it needed it weekly last year has filled the pot with root.
Repot in warmth, never in the cold
Repotting breaks roots, and the plant has to grow replacements. That only happens while the room is warm and the plant is actively growing, which is a much narrower window than for most houseplants because this one shuts down early in autumn.
| Season | Repot? | Reason |
|---|---|---|
| Late spring | Best time | Warmth rising, roots replace quickly |
| Summer | Good | Fastest recovery, but keep it shaded afterwards |
| Early autumn | Only if urgent | Needs six weeks of warmth before nights cool |
| Late autumn to early spring | Avoid | Cut roots sit cold and wet, and rot |
If a plant is collapsing from root rot in midwinter, repot it anyway. An emergency repot into dry fresh compost beats leaving it in rotting wet compost until spring, but keep it warm afterwards and water it very sparingly.
One size up, and no more
The single commonest repotting mistake is jumping two or three sizes to save doing it again. The plant cannot fill that volume for a year or more, and everything outside the old rootball stays saturated after every watering.
| Current pot | Next pot up | Plant width |
|---|---|---|
| 5 in (13 cm) | 6 in (15 cm) | Up to 12 in (30 cm) across |
| 6 in (15 cm) | 8 in (20 cm) | 12 to 18 in (30 to 45 cm) |
| 8 in (20 cm) | 10 in (25 cm) | 18 to 26 in (45 to 65 cm) |
| 10 in (25 cm) and over | Same pot, fresh mix | When you want to hold the size |
Choose a wide shallow pot over a deep narrow one where you have the choice. The root system is shallow and spreading, and a deep pot leaves a column of wet compost below the roots doing nothing but holding water.
A mix that drains
Straight bagged houseplant compost out of the bag is too dense and too water retentive for this plant, particularly in a cool room in winter. Open it up, and you remove most of the risk of the problems on the watering page.
A mix that works: about five parts houseplant compost, three parts perlite or fine bark, and two parts coarse sand or grit. It should feel gritty, hold together loosely when squeezed damp, and fall apart when you poke it. If it forms a firm ball, add more perlite.
- Do not reuse old compost as it is Old compost has collapsed, lost its structure and holds salts. Replace at least half with fresh material, and shake the worst of the old mix off the roots as you go.
- Skip the crocks A layer of stones in the bottom does not improve drainage and reduces the usable soil volume. What matters is that the mix drains and that the water leaves the saucer.
- Top dress instead, on a big plant Where a plant is too large to handle, scrape off the top two inches (5 cm) of old compost each spring and replace it with fresh. That buys another two years.
Doing it, and the fortnight afterwards
Work in the warm part of the day, have the new pot and mix ready before you start, and handle the plant by the pot rather than by the stems, which snap more easily than they look.
- Water the day before A moist rootball holds together and slides out cleanly. A bone dry one crumbles and takes fine roots with it.
- Loosen the outside of the rootball Tease the outer half inch (1 cm) of roots free with your fingers so they grow outward rather than continuing to circle. Cut off any that are black or hollow.
- Set it at the same depth The stem bases should sit at the same level as before. Burying them deeper is a direct route to stem rot in a plant that is already prone to it.
- Water in once, then stop One thorough watering to settle the mix, then nothing until the surface is properly dry. Freshly cut roots in constantly wet compost rot rather than heal.
- Shade it for two weeks Keep it out of strong light and away from drafts, and do not feed for a month. Fresh compost has enough, and fertilizer on cut roots does damage.
The sap contains calcium oxalate and irritates skin, eyes and mouths. Wear gloves, wash your hands afterwards, and keep offcuts away from children and pets.
Holding a plant at its current size
When you have the plant you want and do not want it larger, repot it into the same pot rather than a bigger one. Shave about a quarter off the outside and bottom of the rootball with a clean knife, put it back with fresh mix packed around it, and take off a proportionate number of the oldest lower leaves.
Write the date and the pot size on a label pushed into the compost, or note it somewhere you will find it. Repotting intervals here are two to three years, which is far longer than anyone reliably remembers, and knowing when you last did it tells you whether small new leaves mean a tight pot or something else entirely.