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A kalanchoe carries several weeks of water in its thick leaves, which changes how you should think about the pot. The plant is not waiting on you; it is drawing on its own reserves, and it only wants the compost wet for a short spell after each watering. Compost that is permanently damp rots the base of the stem, and that is what kills most of the plants that die indoors.
So the interval is never a fixed number of days. Learn how your own pot behaves instead: push a wooden skewer down the side of the compost to the bottom, leave it ten seconds and pull it out. Dark, cool, clinging compost means wait. A skewer that comes out clean and dry means you can water.
| Pot and position | Time to dry through | How to water |
|---|---|---|
| Terracotta at a sunny window in summer | Four to six days | Water the day it dries through |
| Plastic at a bright window in summer | Eight to twelve days | Wait two days after it dries, then water fully |
| Any pot in a cool room in winter | Three weeks or more | A small amount once a month, on a mild morning |
| Standing in a cachepot or a saucer | Water pools unseen at the base | Lift it out to water, and pour the drainage away |
How to water, and where not to put it
The technique matters as much as the timing with this plant, because both the flower heads and the crowded leaf crown hold water and rot if they stay wet.
- Pour onto the compost, not the plant Aim the spout at the compost surface at the edge of the pot, under the leaves. Water sitting in the crown where the leaves meet the stem turns into soft brown rot within days in a cool room.
- Never water over the flowers Wet flower heads go brown and mushy and then mark every bloom below them. If you do splash the flowers, tip the plant gently to shake the water off and stand it somewhere with air moving.
- Water until it runs from the bottom When you do water, water properly: enough that it runs from the drainage hole. Little sips wet only the top inch and leave the roots at the base of the pot permanently dry and permanently damp in turn.
- Empty the saucer after ten minutes Tip away everything that has drained through. A pot left standing in half an inch of water is being watered continuously, whatever your interval says on paper.
- Water in the morning Watering in the evening leaves the compost cold and wet all night, which is the exact combination that rots the stem base. A bright morning gives the surface a day to dry.
Through the year
The pattern is a long dry winter and a moderate summer, with the two changeovers made gradually rather than on a date. In winter, dry is safe and damp is dangerous; err downward every time.
| Season | Interval | Amount | Notes |
|---|---|---|---|
| Spring | Every seven to ten days | Until it drains from the bottom | Restart properly once new leaves appear |
| Summer | Every five to ten days | A full watering in the morning | Stretch it out in humid or wet weather |
| Autumn | Every two to three weeks | A full watering, less often | Taper early. Wet compost plus cold nights rots it |
| Winter | Every three to four weeks | A third of a normal watering | None at all in a room near 50F (10C) |
While the plant is in flower it uses noticeably more water than at rest, but the compost should still dry out between waterings. Do not switch to keeping it damp just because it is blooming.
Too much and too little look different
Both extremes make leaves go limp, so people misread the symptom and water a plant that is already drowning. The compost decides the answer, not the leaf. Feel it before you do anything.
Thirst is easy to fix and reverses within a day. Rot is not, and by the time the lower stem has gone soft and brown the plant usually has to be restarted from cuttings taken above the damage.
| Symptom | The compost | Cause and what to do |
|---|---|---|
| Leaves soft and slightly wrinkled | Bone dry | Thirst. A full watering and it recovers within a day |
| Lower leaves yellow and drop off | Damp | Overwatered. Stop, and move it somewhere brighter with airflow |
| Stem base soft, brown and squashy | Damp | Stem rot. Cut healthy tips above the damage and root them |
| Flowers going brown and mushy | Either | Water on the blooms. Remove them and water at the compost |
| Leaf edges brown and dry | Dry | Left dry too long, or a heater draft. Move it, water fully |
Feeding, and what to write down
Feed only while the plant is actually growing, from spring to early autumn, and use a high potassium feed such as a tomato food at half the stated strength every three or four weeks. A high nitrogen feed gives you big soft leaves and fewer flowers, which is the opposite of what you want from this plant. Stop feeding altogether once the dark treatment starts and through the winter.
Keep two figures in a record and next year becomes much easier: the number of days between waterings in each season for your own pot, and the date you last watered before any soft leaf or rot appeared. After one full year those two numbers tell you exactly how far you can stretch your intervals, which is knowledge no general guide can give you because it depends on your pot, your room and your window.
Note the position of the plant alongside the interval. The same plant moved from a window to a table across the room can want half as much water, and an interval recorded without its position is not much use later.