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Our top 10 gardening tips for September

Our top 10 gardening tips for September

September sees the end of summer. Specifically, on the twenty-third of the month, we’ll be saying hello to autumn.

We know, we know. Time goes so fast. How can it nearly be the end of summer?

Look on the bright side. The days are getting shorter and cooler, but you still have plenty of time to enjoy your garden.

Also, September is the perfect time to get your garden ready for the winter… yes, that’ll be here before you know it as well!

To help you get started in your garden this month, we’ve pulled together our top 10 September gardening tips.

You can scroll down to read each of our tips in order, or you can click the links below to be taken straight to specific tips:

  1. Tidy your borders
  2. Dig up your hardy annuals
  3. Harvest your onions
  4. Prune your fruit trees to prevent diseases
  5. Plant garlic, spinach, and peas
  6. Make your own compost
  7. Sort your plant containers
  8. Cut back your tall shrubs
  9. Stock up with spring-flowering bulbs
  10. Keep your patio displays looking good

1. Tidy your borders

We hate to labour the point, but it’s very important: summer is ending

A major downside of this is that September will see the decline of summer bedding plants and hardy perennials like asters, coreopsis, and rudbeckia.

To keep your garden neat and to stop the spread of diseases, you need to remove any dead growth.

Discard or burn any to prevent infections from spreading to your plants the following year. The remainder can be added to your compost pile.

On the other hand, wildlife will eat the seeds and old stems can look quite lovely when covered in frost. So, you might want to leave a few in place until the new year.

2. Dig up your hardy annuals

Unlike their half-hardy cousins, which ought to still be colourful and lovely, most hardy annuals will have wound down by September.

Any seeds you want to save for the following year should be gathered and placed in labelled envelopes.

After this, dig up the plants you want to discard and add them to your compost pile.

The extra space can then be used to plant bulbs or springtime flowers like wallflowers.

If you’re lacking in the needed tools, check out our range of forks, spades, and edging tools.

3. Harvest your onions

The end of September is a perfect time to harvest onions planted in the spring.

This is because the coming of cooler weather minimised the risk of damage from direct sun.

If you’re unsure, a week or two after the leaves start to turn yellow is the ideal time to harvest.

Leave the onions outside directly on top of the soil (out of the rain!) for about a week after harvesting. The outer layer will have time to harden and become less brittle.

4. Prune your fruit trees to prevent diseases

Pruning out any dead, diseased, or dejected-looking branches in September is a good idea.

This is because fruit tree diseases can get worse over the winter.

Pruning, however, can actually worsen disease in trees that produce fruit with stones, such as peaches, plums, cherries, or apricots. So don't prune those ones!

To begin the process, remove any branches that are dead, sick, or that are crossing each other.

For the majority of varieties, you can trim the sideshoots back to three buds to encourage them to develop into fruiting spurs after trimming the central shoots by a quarter.

Only a few of the shoots that have already produced fruit need to be removed from varieties that don't produce spurs (tip bearers), such as the Worcester Pearmain apple variety.

If you’re lacking the required tools for pruning, we have selections of loppers and secateurs.

Not sure which are used in what circumstances or how? Don’t worry, we’ve already written an article about the differences between loppers and secateurs that will get you up to speed.

5. Plant garlic, spinach, and peas

It’s a good idea to plant a selection of vegetables in September. This is because doing so will:

  • Give you an earlier crop in the spring
  • Use otherwise unused soil
  • Save you time when planting in the spring.

Plant your garlic cloves 2.5cm deep and 25cm apart in fertile soil. You should see shoots appear before autumn and overwinter, then put on fresh growth in spring.

Spinach can be sown now for pickings next spring. Sow direct in shallow drills in well-prepared soil, or in pots. Cover with fleece or a low cloche from October onwards.

Peas can be sown in September for an early crop. Choose winter-hardy varieties such as ‘Douce Provence’ or ‘Meteor’.

6. Make your own compost

This time of year, there is always a lot of clearing and pruning to be done in the garden.

Therefore, now is the perfect time to get your hands on a compost bin.

Garden waste can be easily disposed of through composting, which also yields a useful supply of homemade soil enhancer!

7. Sort your plant containers

As your summer containers are finishing up, it's time to plant new flowers for autumn and winter colour.

Your local garden will have a wide selection of plants for you to choose from.

It's important to keep in mind that plants don't grow much in the winter, so pick bigger ones and group them together closely for the best display.

If you don’t have any already (or just want a refresh!), check out our range of planters.

8. Cut back your tall shrubs

Windy weather at this time of year has the potential to harm plants and even ruin your late-summer display.

It’s wise to use canes to support overly heavy plants, such as dahlias and chrysanthemums, in order to lower this risk.

Similar to this, by the end of summer, fast-growing shrubs like buddleia, lavatera, and climbing roses have typically gotten quite tall.

Reduce the height of their tallest stems by a third to prevent these from being harmed by strong winds.

9. Stock up with spring-flowering bulbs

In September, garden centres will be stocked to the brim with spring-flowering bulbs.

If you intend to purchase them, act quickly to ensure that you get the best specimens and the most varied selection.

Examine those that feel firm to the touch and don't exhibit any mould symptoms. Choose large bulbs because they usually produce the best display.

Most bulbs should be planted as soon as possible, but tulip bulbs should wait until November to avoid contracting a disease.

10. Keep your patio displays looking good

It will probably be a month or two before the first post-summer frosts appear.

To maintain the best appearance for your display of delicate plants in pots and hanging baskets, remove flowers as they wilt, water if the compost feels dry, and feed once a week with a soluble feed.

Any slow-release fertiliser applied at planting time will now be beginning to lose its potency; however, giving plants a liquid food will rev them up.


That's it for this month.

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We hope that you've got everything you need to be the top-level gardener we know you are!

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