Monty Don Reveals the Three Plants You Must Prune Before September ends

As the final warmth of summer fades and September settles in, gardeners face one of the most decisive moments of the year. Autumn is not only about harvesting—it’s about preparation. What you do now determines whether your plants will thrive or struggle once spring returns. According to Monty Don, the nation’s most trusted gardening voice, three plants in particular demand attention before the chill of winter takes hold. Miss them, and you risk losing their strength, form, and beauty next year.

Before reaching for your secateurs, Monty offers one essential reminder: keep them spotless and razor-sharp. A clean cut isn’t just neat—it protects your plants from infection and speeds their recovery.

1. Lavender – Stopping Woody Decline

Lavender is a favorite in British gardens, but it can quickly lose its charm if neglected. Monty warns that without annual pruning, the plant becomes “woody and leggy,” losing its neat mound and fragrance-filled appeal. The trick is to prune before flowers fade completely.

Cut back boldly to shape a tidy dome, but always leave some fresh green shoots on each branch. Lavender cannot regenerate from bare wood, so these young shoots will keep the plant alive and vibrant. By acting early, you give it time to recover before frosts arrive—ensuring next summer’s blooms are as lush as ever.

2. Shrub Roses – Encouraging Next Year’s Abundance

Roses may be resilient, but even the toughest shrub roses need guidance to perform at their best. Monty explains that September pruning sets them up for stronger growth and longer flowering periods. For those nervous about cutting back, he reassures that with varieties like English roses or gallicas, precision isn’t required.

Simply take shears and trim away straggly growth, reducing the bush to about two-thirds of its size. Picture shaping a hedge—compact and slightly domed. This quick September tidy-up lays the groundwork. Then, come March, when leaves are gone, you can refine the shape and remove damaged stems.

Think of it as stage one of a two-part strategy, with this early prune ensuring the roses don’t sprawl or weaken over winter.

3. Summer Raspberries – Securing Next Year’s Harvest

Perhaps the most vital task lies in the raspberry patch. Summer-fruiting raspberries only fruit on new canes, which means the old brown stems that carried this year’s berries are now redundant. Monty instructs gardeners to cut these spent canes right down to the soil, leaving only the strong, green canes that will bear fruit next summer.

Thin them out to the six healthiest stems, tying them firmly to wires stretched between posts. This secure framework is critical; without it, winter winds can batter and snap the delicate canes. Neglecting this step risks overcrowded growth, weaker fruit, and even plant death as exhausted stems deteriorate.

Raspberry Pruning Recap Table