Gadenin日本語Get the appSnap the whole stalk off, not the petals
This is the one technique that separates a geranium that flowers all season from one that peters out in midsummer. A geranium flower is not a single bloom but a head of many small flowers on a long bare stalk that rises out of a leaf joint. When the head is finished, the petals drop untidily and leave you looking at a stalk carrying green seed pods and a few clinging brown petals.
Picking the dead petals off does nothing useful. The stalk still stands there, still feeding developing seed, and the plant will not send a replacement bud from that joint while it is there. Take the whole stalk instead. Follow it right down to where it emerges from the main stem and remove it there, leaving no stub.
The stalk is designed to come away. Hold it low down and push it sharply sideways with your thumb and it snaps off cleanly at a natural joint with an audible click, the way a rhubarb stalk pulls. If it bends and tears rather than snapping, it is not ready, or you are gripping too far up the stalk. Do it every few days and the plant is never carrying seed for long.
- Wait until the head is genuinely over Most florets browned, petals dropping, and small green seed pods swelling behind them. A head with even a few fresh florets still open is worth leaving another few days.
- Trace the stalk to its base Run your fingers down the bare stalk to the point where it leaves the main stem at a leaf joint. That joint is where the snap has to happen, not halfway up.
- Push sideways, do not pull A sharp sideways push with the thumb breaks the joint cleanly. Pulling straight out tears strips of skin off the main stem, which then dries back and lets rot in.
- Clear the debris off the compost Fallen petals and snapped stalks left lying on wet compost are where gray mold begins. Pick them up at the same time rather than leaving them for later.
A stub of stalk left behind dies back to the main stem and rots. If a stalk will not snap cleanly, cut it flush with a sharp blade instead of leaving an inch of dying tissue.
Slightly pot bound is the flowering condition
A geranium moved into a generous pot with plenty of fresh compost spends the whole summer filling that pot with root and leaf, and flowers very little. The same plant in a pot that looks slightly too small for it flowers hard from early summer onwards. This is not a myth and it is the most useful thing to know about the plant.
In practice, keep the pot only one size larger than the rootball and be content to leave a plant in the same pot for two seasons. A five to six inch (13 to 15 cm) pot suits a single well grown plant, and three plants will flower better in a twelve inch (30 cm) container than one plant will in the same space. In the open ground, plant into unimproved soil rather than a bed that has just been manured.
The signal that the plant genuinely needs more room is different from being merely snug. Water running straight through in seconds, roots coiling out of the drainage holes, and the plant wilting daily even in mild weather means it has run out of compost. Repot then, in spring rather than midseason, and go up only one size.
| Condition | Effect on flowering | Recommended action |
|---|---|---|
| Snug pot, roots filling the compost | Best flowering | Leave it; feed lightly if compost is old |
| Pot two or three sizes too big | Leaf and root, few flowers | Repot down in spring to a snug pot |
| Rich soil or regular high nitrogen feed | Big soft plant, almost no buds | Stop feeding; buds return in about three weeks |
| Fewer than six hours of direct sun | Stretched stems, sparse pale heads | Move into full sun; flowering follows within a month |
| Night temperatures below 50F (10C) | Buds stall or drop before opening | Wait for warmth, or move under cover overnight |
Sun and warmth set the pace
Geraniums need six hours of direct sun as a minimum and are happiest with eight. In less than that the stems stretch between leaves, the flower heads come small and washed out, and the plant leans hard towards the light. Nothing else you do compensates for a shady position.
Flowering also has a temperature floor. Buds form freely once nights stay above about 55F (13C) and slow markedly when nights fall below 50F (10C). That is why a plant put outside too early in spring sits and does nothing for weeks, then suddenly flowers when the weather turns. It was never sick.
Heat at the other extreme causes a different pause. In a long spell above 90F (32C) many geraniums stop setting new buds and simply hold on. Keep them watered properly through it and flowering resumes on its own when the temperature drops.
Restarting a plant that has gone leafy
A geranium that is all leaf and no flower is a fixable plant, and the fix is subtraction rather than addition. Stop feeding entirely. Let the compost dry further between waterings than you have been. Move it to the sunniest place you have. Then wait three weeks before expecting anything, because the plant has to use up the nitrogen already in its tissue before it will change behavior.
If it is also tall and bare at the base, cut the longest stems back by a third at the same time, cutting just above a leaf joint. Use the tops as cuttings. The plant breaks from below the cuts within a fortnight and those new shoots carry flower buds.
Keep a note of which plants did this and what they were growing in. A geranium that goes leafy in a particular bed or a particular compost will do it again, and the record is worth more than any general rule about feeding.
First flowers open roughly ten to twelve weeks from a spring rooted cutting. If a young plant is not flowering yet in early summer, it may simply be too young rather than doing anything wrong.