Gadenin日本語Get the appWater by the plant, not by the calendar
Sedum leaves are its water tank. A healthy leaf is firm and slightly springy when you press it between finger and thumb. When the plant has drawn the tank down, the leaves go soft and slightly wrinkled, and on creeping types the mat looks dull and flat. That is the signal to water, and it is the only signal worth acting on.
Wrinkling is not an emergency. A sedum can sit wrinkled for a fortnight and recover completely within a day of a soaking. Rot cannot be recovered from. When you are unsure, wait.
| Situation | How often | How much |
|---|---|---|
| Established clump in the ground | Not at all except in a long drought | A single deep soak, then nothing for weeks |
| Newly planted, first season | Every ten to fourteen days if no rain | Enough to wet the root ball right through |
| Container in summer heat | When the leaves lose their firmness | Until it runs from the drainage holes |
| Container in spring or autumn | Every two to three weeks at most | Half as much, and let it drain fully |
| Anything in winter, outdoors | Never | None. Keep rain off pots if you can |
Soak it, then leave it alone
Frequent small waterings are worse than useless. They keep the top inch of soil damp, which is where the crown and the lowest leaves sit, while the deeper roots stay dry and never extend. That produces a shallow-rooted plant that then needs watering more often, and a permanently damp collar that rots.
When you do water, water properly. Put the can spout at soil level and fill the surface until the water stands, let it sink, and fill again. Then do not touch it until the leaves tell you. In the ground that interval will often be a month or more.
- Water in the morning The leaves and the crown dry through the day. Evening watering in cool weather leaves the plant wet all night, which is how mildew and stem rot start.
- Aim at the soil, not the plant Water that sits in the rosettes of a creeping mat or in the leaf joints of a tall stem stays there. Direct the flow at the ground around the clump.
- Check the weight of a pot instead of the surface Gravel-topped compost looks dry when the middle is soaked. Lift the pot: a watered pot is obviously heavier, and you will learn the difference in two waterings.
- Stop watering tall types once buds show Water while the flower heads are filling makes the stems soft and is a direct cause of flopping. From bud color to flowering, leave them dry.
Overwatering, and what it looks like
Overwatered sedum does not wilt in the way a normal plant does. The leaves go translucent, then yellow, then squashy, and they drop off at the slightest touch. Lower leaves go first, and the base of the stem darkens. By the time the stem is soft at ground level, that stem is gone, and if the whole crown is soft the plant is finished.
| Symptom | Cause | What to do |
|---|---|---|
| Leaves soft and slightly wrinkled | Genuinely dry | One deep soak. It recovers within a day |
| Leaves translucent and squashy, dropping off | Overwatered | Stop watering. Move the pot somewhere sunny and airy |
| Black or brown mush at the base of a stem | Crown rot from wet cold soil | Cut out the whole affected stem to clean tissue |
| Bare patch in the middle of a creeping mat | Water sat under fallen leaves or debris | Clear the debris, replant rooted pieces into the gap |
| Lower leaves yellowing on a tall clump in summer | Usually normal shading by upper growth | Nothing. Only worry if the stem itself is soft |
Rot in a container is often a drainage hole blocked by compacted compost or a root. If a pot stays wet for more than three days after watering, tip the plant out and check the base before you blame yourself for overwatering.
Winter is the dangerous season
Cold on its own does not kill sedum. Most of the hardy creeping and border types take hard frost without a mark. Cold plus saturated soil kills it quickly, because the roots cannot take up water at low temperatures and the tissue sits waterlogged until it collapses.
In the ground, the answer is drainage and a gravel mulch that keeps the crown out of the mud. In containers, move the pots against a wall under an overhang so winter rain does not land on them, lay them on their side in the wettest weeks if you have nowhere covered, and give no water at all from the first hard frost until growth restarts in spring.
Keep a note of what you actually did
Watering sedum well is a matter of restraint, and restraint is hard to judge from memory. Write down the date of each watering for containers and the date of any watering in the ground, plus whether the plant was wrinkled beforehand. After one season you will have a real interval for your soil and your climate rather than a guess, and you will usually find it is far longer than you assumed.