Pick basil for tonight’s dinner.

Follow the stem before cutting

For a stem harvest, find a healthy pair of leaves below the tip and cut just above them with clean scissors. Leave that pair attached to the plant so new shoots can grow from there. If you only need a leaf or two, take a small amount. You can leave the scissors on the counter until there is enough growth for a stem harvest.

Further reading: University of Minnesota Extension · Growing basil

Let the plant set the portion

A small plant may have enough for a sandwich and still be a long way from supplying a bowl of pesto. Leave plenty of healthy foliage. If the plant is newly established, sparse or struggling, hold off and check its growing conditions. For tonight, you may need to buy extra basil. That is preferable to taking nearly every leaf from a plant you want to keep growing.

Notice flowers and fresh tips

Basil eventually flowers; regular pruning helps maintain leafy growth but does not make the plant last forever. Watch the tips during your usual water check. If you are growing it for leaves, remove developing flower shoots as part of that pruning. After a harvest, look for fresh growth before taking more. There is no need to promise yourself a fixed number of days between cuts.

Further reading: University of Minnesota Extension · Growing basil

Keep the harvest close to the meal

Snip what you need when you are ready to cook. That makes a modest planter useful even when it cannot supply a large recipe. If you regularly have more herbs than you use, freezing or drying may suit the surplus; the method depends on the herb and how you plan to cook with it. Keep a note of what gets eaten before adding more plants.

Further reading: University of Minnesota Extension · Growing herbs