Topping tomatoes in August: getting the last fruit to ripen
Your tomato keeps growing and setting new flowers while the fruit below stays stubbornly green. In late August, one cut decides what actually ripens.
Late August starts the countdown. Anything that flowers now won’t make it to a ripe fruit in our climate — yet the plant keeps pouring energy into it anyway. One cut redirects that energy to where it pays off.
The mistake: the plant just keeps going
An indeterminate tomato grows as long as you let it. In August it happily pushes new shoots, new flower trusses, new tiny fruit — and at first that feels like a win. The catch: from flower to ripe fruit takes roughly six to ten weeks in our climate, depending on the variety — cherry types are quicker than big beefsteaks. Anything flowering in late August wouldn’t be ready before mid or late October, when nights are cool, light is weak, and rot usually shows up faster than colour does.
That energy isn’t lost — it’s just in the wrong place. Instead of feeding the fruit already hanging there, it goes into shoots that won’t deliver anything.
Topping: one cut above the last truss
Topping simply means cutting off the main growing tip. Count the trusses you still want to ripen — usually four to six — then cut two leaves above the topmost one. Those two leaves stay on because they feed exactly that truss and shade it from harsh midday sun.
Use clean, sharp scissors and cut on a dry morning so the wound seals by evening and fungal spores have a harder time. Bush and patio tomatoes usually need no topping at all — they stop growing on their own.
Remove new flowers — yes, all of them
This one feels wrong, but it’s half the job. Every truss you leave now pulls sugar and water out of the system. Pinch it off with your fingers while it’s still soft, along with any marble-sized fruit that’s clearly too late.
Stay on top of the side shoots in the leaf axils as well: go through once a week and rub out anything longer than a finger joint.
Thin the lower leaves, but don’t strip the plant
Anything yellow, spotted or lying on the soil comes off — that’s the entry point for late blight. You can clear up boldly to just below the lowest truss; above that, leave the foliage on.
A stripped plant doesn’t ripen faster. Colour comes from warmth, sugar comes from the leaves. Cut away too much and you get pale, watery tomatoes plus sunscald on the shoulders of the fruit.
Water evenly, feed less
From here on it’s about flavour, not volume. Water less often but deeply, always into the root zone around the plant and never over the leaves — pouring straight against the stem only invites rot. Big swings between bone dry and soaking are the main reason fruit splits.
Stop nitrogen-heavy fertiliser from mid-August — it pushes leafy growth you no longer need. One last potassium-rich feed is fine; after that, water is enough.
What about the green fruit at the end of the season?
When the first cool October nights arrive, harvest everything that has started to lighten or shows a pale shoulder. At room temperature, in a bowl next to a ripe apple, those fruits finish ripening within one or two weeks — the apple releases ethylene and gets things moving. Store them airy and out of bright light, never in the fridge.
One caveat: completely hard, unripe green tomatoes contain solanine, and cooking or preserving does not break it down. Raw, they don’t belong on the plate at all. Even cooked — in a chutney, say — they should only make up a small share. Letting them ripen off the plant is by far the safest route.
Worth writing down for next year
The right moment to top is roughly eight to ten weeks before your first frost — later in mild wine-growing regions than in the alpine foothills. Note down today how many trusses your variety actually ripened, and how high up you made the cut.
In Rootivo you can keep observations like this in the garden journal, attached to the bed itself. Next season you’ll know fairly precisely when it’s time to reach for the scissors.
Im Lexikon: Tomate