Techniques
Pinching out
Removing the soft growing tip of a plant with finger and thumb to encourage bushier growth, or on a cordon tomato to stop it.
Pinching out is one of the simplest jobs in the garden — you literally use your finger and thumb to nip off the soft tip of a shoot. It sounds drastic, but plants respond very well to it, and it's done for two quite different reasons.
Pinching out for bushier plants
Most plants grow upward from a single leading tip, which quietly suppresses the buds lower down the stem. Remove that tip and those side buds spring into life, so the plant branches out and becomes fuller and more productive instead of tall and leggy.
This is the making of a good herb plant. Basil is the classic example: once a young plant has four or five pairs of true leaves, pinch out the very top pair just above a leaf joint, and it quickly throws out two new shoots. Keep doing this through the summer and one seedling becomes a generous, bushy plant. The same trick works on coriander, mint, sweet peas, cosmos and many bedding plants — always cut back to just above a leaf or a pair of leaves, where the new growth will come from.
It also helps to keep pinching out the flower tips on leafy herbs like basil and coriander. Letting them flower triggers bolting, after which the leaves turn bitter and the plant winds down. On flowering plants the same impulse becomes deadheading — removing spent blooms to push out more.
Stopping a cordon tomato
The other meaning of pinching out is to deliberately stop a plant growing taller, and it matters most with cordon (indeterminate) tomatoes. Left alone, these grow up a single stem all season and would happily keep flowering long after the British summer can ripen the fruit.
So once the plant has set a sensible number of trusses — usually four or five outdoors, or six or seven under glass — you pinch out the main growing tip two leaves above the top truss. This redirects the plant's energy into swelling and ripening the tomatoes it already has, rather than chasing fresh growth that won't crop in time.
In a typical UK season that stopping job lands in early to mid August. Cut it too late and you risk a glut of green tomatoes when the frosts arrive. (This is separate from side-shooting, the ongoing removal of the shoots in each leaf joint, which you do all season long.) Our full guide on how to grow tomatoes sets out the timing alongside feeding and watering.
Either way, pinching out costs nothing and takes seconds — a small nip that pays back in bushier herbs and a riper crop.
In a UK garden
In a UK garden, pinching out basil and other herbs is a job for late spring and summer, while you 'stop' a cordon tomato in August so the fruit it has set can ripen before the first autumn frosts.
Example
Nip out the top pair of leaves on a young basil plant once it has four or five sets of leaves, and within a fortnight it sends out two new side-shoots and grows twice as bushy.