When and how to repot a phalaenopsis

Repotting is the single most useful thing you can do for an orchid that has been in the same pot for years, and the thing most owners avoid because it looks alarming. It takes about twenty minutes.

The four signs it is due

1. The medium has broken down. Bark decomposes. After two or three years it is soft, dark and fine — it holds water like compost, which is exactly what an orchid does not want. This is the most common reason and the one nobody notices.
2. Roots are circling the pot wall or pushing the plant upwards out of the pot.
3. Water runs straight through, or sits on top. Both mean the medium is no longer doing its job.
4. Roots are rotting. Brown, soft, hollow. Do not wait for a better moment.

As a rule of thumb, every one to two years. The medium decides, not the calendar.

When

After flowering has finished, ideally when you can see new root growth starting — green tips emerging from the base.

Repotting a plant in full flower is possible and it will usually drop the flowers, because it redirects energy to root recovery. Unless the roots are actively rotting, wait.

Here in south Florida, spring is the natural window: warm enough for fast root recovery, before the heaviest of the wet season.

What you need

• A slotted pot, the same size or one step up — only if roots genuinely fill the current one
• Fresh orchid bark, soaked in water for an hour beforehand
• Scissors, sterilised with rubbing alcohol
• A stake and clips if the plant needs support afterwards

Soaking the bark matters. Dry bark repels water for the first few waterings, and it draws moisture out of the roots in the meantime.

Step by step

1. Ease the plant out. Squeeze a plastic pot to release the roots. If they are stuck to the wall, run a thin blade round the inside. Never pull by the leaves.
2. Remove all the old medium. All of it. Old broken-down bark left among the roots carries on decomposing and holds water in the new pot.
3. Rinse the roots under tepid water. This softens them slightly and makes the dead ones obvious.
4. Cut away every dead root — brown, soft, hollow. Cut back to firm tissue. Do not trim healthy roots to make the plant fit; choose a bigger pot instead.
5. Choose the pot. Roots should fill it without being coiled. Smaller is safer than larger.
6. Position the plant with the base of the lowest leaf level with the pot rim, roots spread down and outwards.
7. Add bark around the roots, tapping the pot to settle it. Push gently with fingers or a chopstick. Firm enough that the plant does not rock, loose enough to see air gaps.
8. Do not water for a few days. Cut root ends need to callus over. Watering immediately into fresh cuts invites rot.

Afterwards

Bright shade for two weeks, out of direct sun and out of the wind. The plant has fewer working roots than it did and cannot replace the water its leaves lose.

Water sparingly until new root growth appears. This is where people lose plants — the medium is fresh and open, so it looks dry on top while the reduced root system is taking up very little.

No fertiliser for three to four weeks.

Some leaf wrinkling in the fortnight after repotting is normal. Wrinkling that continues past a month means the roots are not recovering.

Aerial roots

Leave them out. Do not force aerial roots into the pot — they are adapted to air, they will snap when bent, and they often rot when buried.

If almost all the roots are dead

Not necessarily fatal. Cut away everything dead, pot into a small container with barely damp sphagnum, keep it humid and shaded, and wait. Phalaenopsis regenerate roots from the base given warmth and humidity — both of which this climate supplies free.

Do not water heavily to compensate. The problem was never a shortage of water.

Sterilising between plants

Rubbing alcohol on the scissors between every plant. Orchid viruses spread on cutting tools, and there is no treatment once a plant has one. It takes five seconds.

Where to look

Slotted pots in every size, including assortments that cover a repotting session across several plants, are on the clear slotted orchid pots page. Ceramic pots with drainage and saucers are at ceramic and self-watering pots, nursery pots and pruning tools at nursery pots and tools, and supports for afterwards at plant stakes and supports and orchid clips.