Gadenin日本語Get the appRepot in the growing season
Repotting always breaks some roots, and the plant has to replace them. That only happens while it is actively growing and the room is warm, which is why the season matters more than convenience.
| Season | Repot? | Why |
|---|---|---|
| Late spring | Best | Warmth is rising and new roots come quickly |
| Summer | Yes, with care afterwards | It transpires heavily, so cut roots means wilting |
| Early autumn | Yes, early in the season | Time to root before the cold |
| Late autumn to early spring | Avoid | Roots do not move and cut surfaces rot |
Signs it is pot bound
A monstera does not need repotting annually. Look for these signs rather than working to a schedule.
- Water runs straight through Water appears at the bottom immediately and the compost barely wets. The roots have filled the pot and the water has found channels rather than soil.
- Roots out of the drainage holes White roots pushing out of the bottom mean they have run out of room. So does lifting the plant and finding the whole rootball comes with it as one block.
- New leaves getting smaller If light and feeding are adequate but each new leaf is smaller and less divided than the last, the roots cannot supply it.
- The pot tips over easily When the top has outgrown the weight of the pot, the roots are equally cramped. The balance between plant and pot is itself a signal.
One size up, no more
Moving into a much larger pot leaves a mass of compost with no roots in it, and that compost stays wet. That is one of the most common causes of root rot in an otherwise healthy plant.
| Current pot | Next pot | Plant height |
|---|---|---|
| 6 in (15 cm) | 7 in (18 cm) | 12 to 20 in (30 to 50 cm) |
| 7 in (18 cm) | 8 in (21 cm) | 20 to 28 in (50 to 70 cm) |
| 8 in (21 cm) | 10 in (24 cm) | 28 to 40 in (70 to 100 cm) |
| 10 in (24 cm) and up | Same size, fresh compost | When you do not want it larger |
To keep a plant the same size, shave about a third off the outside of the rootball, put it back in the same pot with fresh compost, and reduce the top by roughly the same proportion.
Mix for drainage
Monstera roots are thick and want air. A dense, water retentive compost is the single most common reason an indoor monstera declines, so build the mix around drainage.
- A workable mix Roughly six parts houseplant compost, two parts a granular loam and two parts perlite or fine bark. Increase the loam if it dries faster than you want to water.
- Bark helps Adding orchid bark opens the mix further and suits a plant on a moss pole, which wants more air at the roots.
- Do not reuse old compost as it is Old compost has collapsed and drains poorly. Replace at least half of it with fresh.
After repotting
The fortnight after repotting decides whether the plant sails through or sulks. Keep it out of strong light, water it in once and then let it be.
Do not feed for about a month. Fresh compost holds enough, and fertilizer on newly cut roots does damage rather than good.
Do not repot and divide, or repot and cut back, on the same day. One operation at a time.
Dividing to reduce the size
When a plant has outgrown the space, dividing it is better than repotting it larger. Separate at a natural point where two stems come from the base, keeping roots on both halves.
Only divide in late spring or early summer. A division made at the end of summer goes into winter without a full root system and rarely comes through well.
The sap contains calcium oxalate and irritates skin and mouths. Wear gloves, and keep cut pieces away from children and pets.