Gardening Tips September

It’s September - the last of the summer sun is still peeking through the clouds, and the evenings are starting to draw in a little earlier. Although it’s starting to cool down, there’s still plenty of jobs to do in the garden this month.

As we transition into autumn, now is the perfect time to plant late blooming perennials to get some beautiful pops of colour in your garden before winter sets in. You can also start planting your spring flowering bulbs, ready for blooms next year.

Let’s take a look at what to plant in September, and everything you need to do get your garden ready for autumn!

Your September gardening checklist

September is the time for refreshing the garden and preparing for next year. Soil will still be warm from summer, but cool air and rain showers will soon start making the ideal conditions for roots to grow.

Tidy up the summer-flowering perennials

In the post-summer weeks when plants are at optimal growth, overcrowding can be a problem as plants start to compete for light and nutrients. Dig up any overcrowded established herbaceous perennials, such as hostas, geraniums and salvias to restore healthy roots and promote beautiful blooms. If the plants are large and healthy, consider splitting them at the root ball. You’ll get more plants and promote better growth!

Now is also the time to revitalise any tired looking perennials. Perennials often grow new shoots around the edge which can lead to a woody, flowerless core. Lift the clump, throw away the dead middle and replant the outer growth for a stronger, fuller bloom next year.

Time to take cuttings

In September you can begin to take semi-ripe cuttings from tender plants. First select plants with healthy shoots and take 10cm cuttings from these perennials and shrubs. Salvias, penstemons, fuchsias and lavender can all produce cuttings this month.

Dip the cut steams into Vitax Organic Rooting Powder before potting to accelerate root growth and aid establishment over autumn. Protect cuttings in a cold frame or greenhouse over winter so they aren’t damaged by frost or bad weather.

Not sure where to start with cuttings? Take a look at our guide on How to Take Cuttings.

Prep the garden for the winter months

Although there is a little while until frost arrives, nighttime temperatures in September can drop to below 10 degrees Celsius. With that in mind, keep an eye on the weather and position any sun-loving or sensitive plants to the greenhouse or other sheltered space.

Deadheading is also a key job for this month. You’ve likely been deadheading throughout summer, but continue to tend to dahlias, roses and cosmos to prolong any flower displays right up until the first frost.

Make sure you collect any plants seeds on dry, still days - this is a great activity to keep children busy in September! Seeds from foxgloves, snapdragons and poppies can be dried and stored in paper bags, ready for spring. Consider leaving hardier seedheads like echinacea, allium, and teasel standing, as they add great texture to a winter garden and birds will need the seeds in the colder months.

What should I plant in September?

Planting spring-flowering bulbs

Sow hardy annuals

As well as bulbs, you can also sow hardy annuals in September, such as sweet peas, cornflowers, calendula and poppies. Seeds sown this time of year build deeper root systems over winter, resulting in larger, stronger plants that flower earlier.

However, don’t forget it will get colder in the next few months so you will need to make sure any young seedlings are under fleece through harsh frosts.

Freshen up container displays

Why not give your summer containers a fresh start this month? Top up the soil in window boxes, hanging baskets and patio pots where needed, and choose hardy plants that can survive the cooler months. Winter flowering plants, like pansies, cyclamen, chrysanthemums and asters add a lovely pop of colour and create a full flowering display throughout autumn.

Use fresh peat free compost when replanting, and raise containers onto pot feet to help improve draining and prevent waterlogging.

Want to know more about keeping your garden in top condition throughout the year? Read our month-by-month expert tips and guidance on our Blogs & News page.