September pruning is not a yard-wide haircut. Focus on indeterminate tomatoes, basil, lavender, wisteria, garden phlox, daylilies, and currants or gooseberries, making only the light, plant-specific cuts that improve ripening, shape, flowering, or health before cold weather.
The rule is to work early in the month, use clean sharp essential pruning tools, and stop if a plant is already responding to chilly nights; in Zones 3–5, that moment arrives much faster than it does in temperate Zones 7–9.
