Planting A Container for Autumn Colour

By mid-September, many summer-flowering annuals have started to burn themselves out. They’ve given their all, and their natural instinct is now to produce seed before the weather gets colder and they die. This can leave pots and containers planted in late spring looking rather forlorn. If you’re not ready to resign yourself to the onset of winter, there’s still plenty of time to plant up a container for a glowing autumn display that will see you through Halloween and Bonfire Night into November. Where we live, it’s unusual to get heavy frosts before Christmas, so we still have a good 12-14 weeks to enjoy some seasonal colour before winter arrives. Even in colder regions, there’s a wide range of perennial plants that will flower until Christmas if the weather is kind.

The autumn season lends itself to fiery colours such as red, orange, yellow, pure white, plum and purple. These echo the colours of gardens and countryside as the foliage starts to turn before falling. It also happens that many autumn-flowering plants, such as rudbeckias, heleniums, Michaelmas daisies, salvias, chrysanthemums and crocosmias, are rich in cultivars at the ‘hot’ end of the colour spectrum.

For my autumn planter, I have chosen several perennial plants. The advantage of perennials is that they can be planted out in the garden once their flowers start to fade (but before the ground becomes frozen). They will overwinter and start growing again next spring when the weather is warmer. Chilli peppers won’t survive a winter in the UK, so I’ll be cropping the chillies* and disposing of the rest of the plant on the compost heap. Cheerful Bidens ferulifolia ‘Beedance Painted Red’ may return for another year or two if it’s happy, but is generally grown as an annual plant in the UK. Aeonium arboreum ‘Zwartkop’ is a succulent plant and will need winter protection in all but the mildest parts of the UK. Mine will go into an unheated greenhouse before the first frosts.

To replicate my planting scheme, you will need:

1. 1 x terracotta pot measuring 14 inches (36cm)
2. Peat-free potting compost
3. Potting grit (horticultural grit)
4. Moss or crocks
5. 1 x Crocosmia (montbretia) – yellow or orange as you prefer
6. 1 x Aeonium arboreum ‘Zwartkop’
7. 1 x Bidens ferulifolia (Apache beggarticks)
8. 1 x Capsicum annuum (chilli pepper) ‘Orange Wonder’
9. 1 x Heuchera ‘Black Beauty’
10. 2 x Uncinia rubra (red hook sedge)

Watch my ‘how to’ video here:

The first step is to take a clean terracotta pot (you can use a resin, plastic or concrete planter if you prefer) with at least one drainage hole in the bottom. Cover the drainage hole with a piece of moss or crocks to prevent the compost from falling through the hole. This isn’t essential; the main thing is that excess water can drain away from the base of the pot.

Fill the pot around two-thirds of the way up with peat-free compost. I use a formula that includes biochar, coir (from coconut husks), seaweed, worm casts and mycorrhizal fungi. I add a little potting grit to aid drainage. Biochar helps retain moisture and improve the structure of the compost, mycorrhizal fungi encourage strong root development and the worm casts and seaweed provide nourishment. Coir is far more sustainable and longer-lasting than peat.

Now you are ready to plant. At this point in the year, plants are unlikely to grow very much more, so you can pack them in without any risk of them becoming overcrowded later on. What you want is an instant display. That said, if you’re at the garden centre or nursery and you have a choice between a plant that’s still in bud, or one that’s already in full bloom, select the one that’s in bud. That way you’ll enjoy a longer-lasting display, as plants already flowering their socks off are likely to run out of steam sooner.

Gently ease each plant from its pot. If it’s very packed with roots you may want to tease the rootball out a little bit to help the plant get established in its new container. I would always start with the tallest or biggest plant, fitting that in towards the back. Then you can start adding other plants, making sure that the level where the plants emerge from the compost is consistent – you don’t want any of the plants getting buried or standing proud at the end. If the plant is dropping down too low, add a little compost beneath it, and if it’s too high, make a little impression that it can sit down into.

With the crocosmia positioned towards the pack of the pot, I added a ‘feature’ plant, something to draw my eye to the centre of the display. Aeonium arboreum ‘Zwarkop’ is always a showstopper and lends the scheme a slightly decadent, even spooky feeling. The chillies and bidens have similar colour fruits and flowers respectively, but very different forms, which I like. A heuchera echoes the dark, smoky tones of the aeonium and red hook sedge helps to fill any gaps around the base of the pot. Something trailing, like a sedum, would also work nicely at the front and sides of the pot.

Once all the plants are in position it pays to stand back and make adjustments until you are completely happy with the arrangement. Then fill all the gaps between the plants with compost, trying to end up with a level surface about 5cm below the rim of the pot. Water generously to settle the compost around the roots and then top off with potting grit. Potting grit gives a professional finish. More importantly, it helps to retain moisture, prevent compost splashing up on to the foliage and flowers when it rains, and deters pests such as slugs, snails and vine weevils.

You can now stand your finished pot in its final location, taking care to lift it correctly as freshly-watered pots can be very heavy indeed. Although some of the plants I used will tolerate shade, autumn days are shorter and light levels lower, so try to find a bright, sunny spot if you can. How often you need to water will depend on the weather, but I’d suggest a thorough watering at least twice a week. You should not need to feed as there ought to be sufficient nutrients in the compost to keep your plants healthy until it’s time to dismantle the display at the end of autumn. Pick chillies as required* and remove fading flowers from the bidens and crocosmia to encourage more blooms over the coming weeks.

And there you have it, a cheerful, fiery display which will reward you with some welcome autumn colour. Of course, there are infinite plant combinations that would be every bit as glorious, so feel inspired to visit your local garden centre or nursery, see what they have in stock, and create your very own scheme. TFG.

*Take care when handling chillies and make sure you wash your hands afterwards.

Categories: compost, Container gardening, Flowers, Foliage, Perennials, Practical Advice, projects, Weather