Gadenin日本語Get the appWater the mix, not the calendar
A succulent euphorbia stores its own water in the stem, so the useful question is never how many days have passed but whether the compost is dry throughout. Push a wooden skewer or your finger to the bottom of the pot. If it comes out with anything clinging to it, or feels cool and damp, wait. If it is dry and dusty right through, water.
When you do water, water properly. Soak until it runs out of the drainage holes, then let the pot drain completely and never leave it standing in a saucer. Half-hearted splashes wet only the top inch and encourage roots to stay shallow while the bottom of the pot stays permanently moist.
| Conditions | Rough interval | Check first |
|---|---|---|
| Warm bright summer, small pot | Every 10 to 14 days | Skewer comes out dry to the base |
| Warm bright summer, large pot | Every 3 to 4 weeks | Whole pot noticeably light to lift |
| Spring and autumn, growth slowing | Every 3 to 5 weeks | Growth still visibly active |
| Cool room below 55F (13C) | None | Nothing. Keep it dry |
| Warm bright room in winter | A splash every 6 to 8 weeks | Room genuinely stays above 65F (18C) |
Lifting the pot is the quickest test of all. Learn what it weighs the day after a soaking and what it weighs when dry, and you will rarely need the skewer.
How to water without causing rot
Where the water goes matters as much as how much. Pour at the edge of the pot rather than over the crown or into the growing point, and avoid soaking the collar where the stem meets the compost. That collar is where rot begins, and it is the one part of the plant that should dry fastest.
- Check the mix to the bottom Skewer or finger to the base of the pot. Damp anywhere means wait. This single habit prevents most losses.
- Water in the morning, not the evening Morning watering lets the surface and the stem base dry through the warmth of the day. Evening watering leaves them damp through the cool of the night.
- Pour at the pot edge until it runs through Soak the whole root ball rather than wetting the surface. Keep the water off the stem collar and out of the growing point.
- Drain fully and tip away the saucer Let it finish dripping and empty any saucer within a few minutes. A pot standing in water is a pot with permanently wet roots.
- Do not water again until it is dry through Resist topping up. These plants tolerate being too dry for weeks and tolerate being too wet for days.
Reading thirst and reading trouble
A thirsty plant is easy to read once you know what to look for. The stem loses its plumpness and the ribs deepen, the surface takes on a very slight wrinkling, and new growth slows. All of that recovers fully within a week of a good soak and does no lasting harm.
Overwatering shows differently and much more dangerously. There is often no warning at the top at all: the column stays green and firm while the base has already gone soft. Other signals include a yellowish translucent look low on the stem, compost that is still damp two weeks after watering, a sour smell at the surface, and fungus gnats circling the pot.
This asymmetry is why underwatering is the safer error. A euphorbia that has been dry too long is a plant with a problem you can fix in a week. A euphorbia that has been wet too long is often already beyond saving by the time you notice.
| What you see | Likely cause | What to do |
|---|---|---|
| Ribs deepened, stem slightly wrinkled | Too dry | Soak thoroughly. Full recovery in a week |
| Base of stem soft or darkened | Too wet, usually for weeks | Stop watering. Cut above the damage today |
| Yellow translucent patch low on the stem | Rot beginning | Unpot and inspect the roots immediately |
| Compost still damp after two weeks | Mix too heavy or pot too large | Repot into gritty mix in warm weather |
| Fungus gnats around the pot | Surface permanently moist | Water less, add a gravel top dressing |
| New growth thin and pale | Too little light, not thirst | Move it brighter. Do not water more |
Cold and wet together is what kills
Neither cold nor damp on its own is usually fatal. Combined they are, and that combination is the single commonest way these plants die. Below about 55F (13C) the roots barely take up water, so anything you give sits in the pot for weeks against a stem base that cannot dry out. Rot follows, generally showing itself in early spring when people finally look properly.
So the winter rule is simple and absolute: if it is cool, it stays dry. Only a plant in a room that genuinely stays warm and bright gets an occasional small drink. Never water a plant standing on a cold windowsill, and never let rain reach a pot standing outdoors, whatever the season.
If you have to choose between a slightly shriveled plant at the end of winter and a plant you watered through the winter, choose the shriveled one every time. It fills out again in a fortnight.
If you cut into a stem to check for rot, remember that the white sap is caustic and blinding in an eye. Gloves and eye protection first, then rinse the cut with cold water until the flow stops.
Write down when you watered
Watering is the one thing on this plant you genuinely cannot reconstruct from memory, because there is nothing to see afterwards. Keep a simple log: the date of each watering, roughly how much, and where the plant was standing. It takes seconds and it converts a vague sense of having watered recently into a fact.
The two most valuable entries are the date of the last watering before winter and the date of the first watering in spring. Over two or three years those dates, set against any trouble you had at the base, tell you exactly how early you need to stop in your own conditions. Note the pot weight when dry as well, so anyone else looking after the plants has a test they can apply without judgement.