The window for pruning these 7 shrubs and perennials is right now (if you want to keep them healthy), says an expert horticulturist

October is a magical time of year in the garden, when the colors change and temperatures drop. The first frosts of the year hit, leaves drop from the trees, and borders begin to fall from their summer heights.

There are still fall-flowering, hardy perennials that can stand in full bloom in fall, while many shrubs put on spectacular displays to enjoy. Don't just stand and admire that seasonal glory, though, as October is the perfect time to prune certain hedges, shrubs, and perennials.

I spent years working as a professional gardener in large, historic gardens, and October was always a busy month. Primarily, this is the month to prune shrubs and prepare them for winter, tidy up your hedges, and cut back perennials that bloomed during summer but now look a shadow of their former glory. With all that in mind, I highlight seven plants to prune in October and give some trimming tips to keep them healthy.

Plants to prune in October

Not all shrubs and perennial plants need to be trimmed this month. Many can offer attractive seedheads during winter, which will provide food and shelter in a wildlife garden, and should be left until spring.

In addition, some plants should never be pruned in October. The likes of rhododendrons, lilacs, fruit trees, and Japanese maples shouldn't be touched; it would be a pruning mistake to trim them this month.

However, the following seven are definitely plants to prune in October and will actively benefit from some TLC this month:

1. Deciduous hedges

Many deciduous hedges require pruning twice a year, especially if you want to keep them neat and uniform. The likes of beech, hornbeam, and hawthorn are fast-growing hedges that do benefit from a trim in both spring and fall.

Fall can be a good time to prune hedges made of deciduous hedging plants when you live in a cooler climate, where the plants can get at least four weeks to recover before the first winter frosts hit. The trimmed hedges will look neat and give a strong structure to the garden during winter.

It is important to clean and sharpen your hedge trimmer blades before cutting. This needs to be done carefully by securing the blades and sharpening them with a flat file, such as this 10-inch steel file at Amazon. This should be followed up by removing any burrs with a whetstone, such as this whetstone at Walmart.

Cleaning and spraying your trimmers with a lubricating spray after any use can help extend the life of your machine.

2. Early-flowering hellebores

Pruning is a key maintenance task when you grow hellebores, and it is vital both to keep plants neat and to prevent the spread of hellebore leaf spot.

Hellebore leaf spot is a fungal issue that affects the leaves, stems, and flowers of most hellebore types. Pruning hellebores and removing the older stems in the fall is a recommended way to reduce the chances of the disease spreading to new growth.

Early-flowering hellebores can bloom as early as December, such as the popular Helleborus niger or Helleborus orientalis. It is practical to prune these in October or November to remove old brown plant material before the new growth appears.

Always wear gardening gloves when working with hellebores, as all parts of the plants can irritate the skin. Use a pair of clean, sharp pruning shears or garden snips to trim old growth right down to the base.

3. Yew

Yew (Taxus baccata) is a robust and versatile evergreen bush that can be grown as a hedge or as topiary. It featured as a plant for topiary and also large, formal hedges in historic gardens I worked as a gardener. I spent many days and weeks over the years cutting yew, and October was a prime month for doing so.

Yew hedges or topiary can stay neat with just one trim per year, and October represents the end of the window to do this. Regular trimming results in dense growth – perfect for hedges or topiary – and the sharp edges will remain throughout winter and early spring.

You can prune yew hard, and it is recommended to taper the shapes of hedges so that light can reach the lower branches. However, do not cut back into the woody growth, as yew takes a while to resprout from the old wood, and you'll be left with holes in your hedge.

4. Santolina

Santolina, also known as Lavender Cotton, is a fragrant evergreen perennial with gloriously aromatic foliage and pompom-like yellow flowers. It likes a hot, sunny space in a yard and offers a lot as a drought-tolerant flowering perennial in warm climates.

The plant only reaches around two feet tall, but when it does get too tall, the clump can split open. When this happens as a result of being too straggly, the wooden center shows, and admittedly looks unsightly.

While hard pruning is left till spring, santolina also benefits from being cut back in the fall after flowering. You can quickly trim back old flowers and tall shoots in October with a pair of shears to maintain the shape and keep it neat.

You can keep your hedge shears sharp ahead of doing any trimming with this pocket-sized sharpening tool, available at Amazon, which can also be used to sharpen pruning shears or garden scissors.

5. Bearded Iris

When you are growing irises, pruning them in September or October is essential to keep them healthy for the following year. Bearded irises may have a fleeting blooming season of just a few weeks in late spring, but they make a spectacular impact even in that short period.

There are many bearded iris varieties to add to your yard for a display, in a range of different colors from yellow to deep purple. While the foliage wants to be kept in place after the irises bloom, to store energy for next year, the time to cut back irises comes in the fall.

Pruning is important when growing bearded irises, as pests and diseases can strike if it is not done. If you haven't got around to it yet, add cutting back irises to your fall gardening checklist for the month.

It is crucial as diseases like leaf blight, botrytis, leaf spot, and ink spot can all overwinter on old leaf debris. And the eggs of the iris borer can overwinter, too, and hatch to eat the plant next year. A quick prune to cut down the old foliage keeps irises healthy and guarantees a great display next year.

6. Lavatera

Lavatera, or tree mallow, is a classic English garden plant, and the flowering shrub is covered in white or pink blooms from early summer into fall. There are smaller types; however, the varieties to prune in October are the large, shrubby ones that can reach over six feet tall, and this is to keep them protected and healthy.

Proper pruning and shaping of Lavatera should always be done in the spring. However, it is beneficial to head out with the pruning tools to trim those taller varieties this month to prevent wind rock.

Strong winds can cause the shrub to move in the soil, and the roots are susceptible to damage. Tall shrubs can rock back and forth, or, in the worst-case scenario, the whole plant can be toppled in extreme weather.

To prevent issues from wind rock, cut the tall stems back by up to 50% in the fall. As well as Lavatera, you should cut back buddleia, dogwood, or abutilon to protect them from high winds.

7. Bee balm

Bee balm is, as the name suggests, a great plant for pollinators as its flowers attract bees, butterflies, and hummingbirds during the season. Unfortunately, it is also highly susceptible to powdery mildew, and that is why it features here among the plants to prune in October.

Powdery mildew is a fungal issue that is a common problem when growing bee balm. It shows itself as a white coating on leaves, and its spores can overwinter in any living or dead plant material.

While bee balm can provide winter protection for many garden insects, if your plant succumbs to powdery mildew, it can also protect the spores, which will infect new growth come spring.

It is safer to cut back bee balm stems in the fall and, if your plants do show signs of powdery mildew, to bin the material and never use it to make compost.

Shop essential pruning tools

If you are after more inspiration for what you can and can't trim this month, we're here to help. We have guides on trees to prune in October and perennials to cut back in the fall to help you have a pruning plan for the month. It means you can head out with your pruning tools with confidence.