Gadenin日本語Get the appWhen the job is due, and when it is dangerous
Repot at the start of the growing season, meaning autumn once the heat has broken, or early spring while the plant is still working. Roots that are active will bridge into fresh mix within two or three weeks and the plant hardly notices the disturbance. The same job done in the middle of the summer rest leaves cut roots sitting in damp mix with no capacity to heal, and that is one of the most reliable ways to lose a good specimen.
The usual interval is every two to three years, and there are three signals that it is time. Roots showing at the drainage holes or lifting the plant in its pot; water running straight through in seconds because the mix has broken down into dust and channels; and a plant that will not stand up because the head has outgrown the root plate. That last one is the most common reason with this plant and it is a stability problem as much as a horticultural one.
Choosing the container
Weight and width matter more than depth. An aeonium carries a heavy head on a bare stem over a shallow, fibrous root system, so a lightweight plastic pot that is taller than it is wide will topple in the first gust or the first time somebody brushes past it. Terracotta or glazed stoneware, wider than it is deep, gives the ballast the plant does not have, and unglazed clay also dries the mix faster, which suits the plant in winter.
Go up one size only, roughly an inch to two inches (3 to 5 cm) of extra diameter. Overpotting is a real risk here because the excess mix around a small root ball holds water long after the roots have taken what they need, and in the cool wet months that is a slow route to base rot. Multiple drainage holes are essential and a cache pot with no outlet is not a container, whatever it looks like.
The mix
Aim for something that drains within seconds but does not go dust dry within a day, because unlike most succulents this plant is watered regularly for half the year. Roughly half mineral grit and half a decent open potting mix is the working target, which is a slightly richer mix than you would give a thick-leaved succulent.
| Component | Proportion | Why it is in there |
|---|---|---|
| Pumice, coarse perlite or 2 to 6 mm grit | About half the volume | Fast drainage and air around the roots |
| Loam-based or good all-purpose potting mix | About a third | Holds enough moisture for the long winter growing season |
| Composted bark or coir chips | Up to a fifth | Keeps the structure open as the compost ages |
| Coarse sand or fine gravel at the pot base | A thin layer, optional | Adds ballast low down in the pot |
| Grit top dressing, quarter inch (5 mm) | Surface layer | Keeps the stem base dry and stops splashing |
Do not use a straight cactus mix with no organic content. It suits a summer-growing succulent that is kept nearly dry for months, but an aeonium watered every week or two through winter in pure grit will run short of both water and nutrients.
Doing the job
Work with a plant that has been dry for several days, which makes the old mix fall away cleanly and reduces the chance of tearing live root. Set aside half an hour and have the new pot, mix and top dressing ready before you lift the plant, because an aeonium out of its pot is awkward to put down without snapping a branch.
- Support the head and slide the plant out Spread one hand under the lowest branches to take the weight, tip the pot at an angle and ease the root ball out. Never pull on a stem to lift the plant. If it is stuck, run a knife around the inside edge of the pot rather than tugging.
- Clear the old mix and check the roots Crumble away most of the old mix and look at what is left. Live roots are pale and firm. Cut off anything black, hollow or smelling sour, and cut back into clean tissue. Fat white grubs in the debris are vine weevil and every scrap of that mix must go in the bin.
- Check the base of the stem before you plant it Press the stem where it enters the root ball. It must be hard. If it gives, or shows a brown line inside when you nick it, cut the whole head off above the damage and treat the job as a rerooting rather than a repot.
- Set the plant deeper than it was Aeoniums root readily from the stem, so a leggy plant can be planted with two or three inches (5 to 8 cm) of bare stem below the surface. This lowers the center of gravity, hides the bare wood and gives you a second tier of roots. Firm the mix with your fingers as you fill.
- Top dress, then wait before watering Add a quarter inch (5 mm) of grit over the surface, right up to the stem. Put the plant in bright shade and give no water for 5 to 7 days so any cut roots seal, then water thoroughly and return it to its normal position.
Afterwards, and what to write down
Expect a couple of weeks of no visible change, and possibly a few lower leaves dropped as the plant reallocates. Keep it out of the hardest sun for a fortnight, then treat it normally. If the plant still rocks in the pot after a month, it has not rooted yet, so firm it again and stake it rather than lifting it to check.
Put the repotting date and the mix ratio on a label pushed into the pot. Two years on, that label answers the question of whether this plant is due in one glance. It is also worth noting the pot size you moved up to and whether the plant blew over that winter, because with this species the answer feeds straight into the next repot: if it went over once, go wider and heavier rather than taller next time.