Gadenin日本語Get the appThe year in outline
A kalanchoe run properly is one of the few houseplants with a genuine annual cycle, and that cycle is what turns a plant that flowered once in the shop into one that flowers every winter. Everything hangs off two decisions: cutting it back hard after the flowers fade, and covering it for six weeks in autumn.
If you only remember one thing from the whole year, make it this: nothing you do in spring or summer will produce flowers on its own. The flowers come from the autumn darkness, and the spring and summer work exists to build a plant good enough to carry them.
| Season | Main job | Watering and feeding |
|---|---|---|
| Spring | Cut back hard, propagate the prunings, repot | Every seven to ten days. Start half-strength feed |
| Summer | Grow it on in bright light, pinch the shoots once | Every five to ten days. Feed every three weeks |
| Autumn | Six weeks of fourteen-hour nights | Every two to three weeks. Stop feeding |
| Winter | Flowering. Deadhead, keep it warm and bright | Every three to four weeks. No feed |
Spring: cut it back and start again
As soon as the last flowers have gone over, cut the whole plant back. Take each flowered stem down to a pair of leaves two or three inches (5 to 8 cm) above the base of that shoot, removing the spent flower head and most of the stretched stem with it. It looks brutal and it is exactly right: new shoots break from below every cut, and a plant cut back in spring is bushy by midsummer.
This is also the moment to repot if the plant needs it, and to turn every piece you cut off into a cutting. Cutting back, repotting and propagating in one afternoon is the standard spring session for this plant.
Do not cut into bare brown woody stem with no leaves or dormant buds on it. Cut just above a pair of leaves, or above a visible bud, and the shoot will break reliably.
Summer: build the plant
Summer is for growth and shape. Keep it in bright light but out of direct midday glass, feed at half strength with a high potassium food every three or four weeks, and water only when the compost has dried through. A summer outdoors in bright shade and out of the rain suits it well, but bring it in before nights drop below 50F (10C).
Pinch the tips of the new shoots once, when they have made three or four pairs of leaves. Each pinched tip becomes two, which is what gives you a rounded plant covered in flower heads rather than a few long stems. Do not pinch after late summer, because the shoots need time to mature before the dark treatment starts.
| Job | When | Why |
|---|---|---|
| Pinch the shoot tips | Once, in early summer | Doubles the number of flowering shoots |
| Feed at half strength | Every three or four weeks | High potassium builds flower buds, not soft leaves |
| Shade from midday glass | Through the hottest weeks | Prevents permanent scorch marks on the leaves |
| Bring an outdoor plant in | Before nights fall below 50F (10C) | Cold and damp together rot the stem base |
Autumn: the six weeks that matter
This is the part of the year that people skip, and it is the reason most kalanchoes never flower twice. For six consecutive weeks the plant needs fourteen hours of complete darkness followed by ten hours of bright light each day. A cardboard box over the plant each evening, taken off each morning, is the usual method.
Choose a cool room if you can, because nights around 59 to 64F (15 to 18C) set buds far more readily than a warm living room. Stop feeding for the whole treatment, and stretch the watering interval as the nights cool. When you can see green bud clusters at the shoot tips, the job is done and the box can be put away.
- Start six weeks plus a month before you want flowers Six weeks of treatment, then four to six weeks for the buds to swell and open. Count backwards from the date you want the plant in bloom and mark the start in a diary.
- Cover and uncover at the same times daily Fourteen hours dark, ten hours bright, every day without exception. A single evening in the light restarts the count in practice, so set an alarm rather than relying on memory.
- Check the cover is genuinely dark Look for light leaking under the edge of the box or around a cupboard door. Weight the box down or use a room with proper blackout, because partial darkness gives no result at all.
- Stop when the buds appear Green bud clusters at the tips mean the plant has committed. Return it to the brightest window and let it finish in normal daylight.
Winter: flowering and holding it
In flower, keep the plant in full winter sun, above 50F (10C), and away from cold glass at night. Water when the compost dries through, always at the compost and never over the blooms, and do not feed. A single flowering lasts six to eight weeks and often longer in a cool bright room.
Pick off each flower head as it browns. Deadheading keeps the display clean, stops rot spreading from a mushy old head into the shoot beneath it, and encourages the smaller secondary buds to open. When the last flowers have gone, the year starts again with the spring cut back.
| What you see | What it means | What to do |
|---|---|---|
| Buds forming but dropping before they open | Room too warm, or the compost dried out hard | Move it cooler and water more evenly |
| Flowers fading within a fortnight | Too warm, or too dark | A cool bright room extends the display considerably |
| No buds after six weeks of treatment | Light leaked into the cover, or nights too warm | Repeat with a genuinely dark cover in a cooler room |
| Flower heads browning and going soft | Water splashed on the blooms | Remove them and water only at the compost |
Keep a note of the dates: when you cut it back, when the dark treatment started and finished, and when the first flower opened. After one year those four dates let you set the treatment so the plant flowers exactly when you want it to, which is the whole point of learning the cycle.