How Often to Water Sempervivum: Almost Never, and Never in Winter

Start from how the plant is built

A sempervivum stores its water in thick leaves and drinks through a shallow, fine root system that spreads sideways rather than down. It is adapted to rock crevices where rain arrives, drains away within minutes and then does not return for weeks. Every part of a sensible watering routine follows from that: heavy but infrequent, and always followed by complete drying.

This means the question is never how many days it has been. It is whether the growing mix is dry the whole way through, and whether conditions will let it dry out again quickly afterwards. In a shallow gritty pan in the heat of midsummer the answer might be yes twice a week. In the same pan once autumn has cooled and the plant has stopped growing, the answer is no for four straight months.

Through the year

Houseleeks grow in spring and autumn, slow down in high summer heat, and sit almost still through winter. Watering follows that curve and lags slightly behind it, so you cut back before the plant obviously slows and resume after it has obviously restarted.

How to water, when you do

Water the mix, not the plant. Aim the spout at the surface of the grit at the edge of the pot and let it run through until it comes out of the drainage hole, then stop. Filling the rosettes from overhead leaves water sitting in the tightly packed center where it evaporates slowly, and in cool weather that is the exact mechanism that rots a plant from the middle outwards.

Choose a morning in cool weather so the crown dries by nightfall, and an evening in hot weather so the roots are not scalded and the water is not gone in an hour. Never leave a pot standing in a saucer, tray or outer container that holds run-off. Tip out anything that collects within a few minutes.

Rainwater and tap water are both fine here, which is not true of every succulent. Hard tap water leaves a white crust on the grit but does no harm to the plant. If the look bothers you, top-dress with fresh grit once a year rather than switching your watering habit.

Too much and too little look nothing alike

Underwatering is slow, obvious and easy to reverse. The outer leaves go thin and papery, the rosette closes up tighter, and the whole plant feels slightly soft when squeezed. A single thorough soak fixes it within a few days and does no lasting damage. In practice almost nobody kills a houseleek this way.

Overwatering is fast and final. The base of the rosette goes translucent, then brown, and the leaves detach with almost no resistance. There is often a sour smell. By the time you can see it, the crown has already gone and the plant cannot be saved, though healthy offsets around the outside usually can be. If a rosette pulls out of the mix with no root attached, that was rot, not drought.

One caution about the lowest ring of leaves: they die back and go crisp brown on every healthy houseleek, continuously, all year. That is the plant discarding old leaves as the rosette grows, not a watering fault. Pull them off when they are fully dry and ignore them otherwise.

A watering line worth keeping

Because the correct answer is so often nothing, the useful record here is not every watering but the boundaries. Note the date you last watered before winter and the date you first watered in spring. Those two dates, kept for one year, tell you more than a full log, and they stop the mid-winter impulse to give a plant a drink because it looks a bit dry.

Alongside them, note any week where the pot had more than a couple of days of continuous rain, and whether you moved it under cover. If you lose a rosette to rot, that record almost always points straight at the cause, and next winter you will know to move the pot a fortnight earlier.