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Adding colour in August

Updated: Aug 6, 2021

Thinking about what to plant in August? The key to planning any garden is to aim for some form of interest and colour throughout every month and season of the year.

As summer moves towards its end and we head towards Autumn, you might think your options are running out. But, perhaps surprisingly for some gardeners, there are still lots of things you can plant and sow as part of your flowerbed ideas over the coming weeks.

Firstly, there are mature plants ready to bloom that can go in the ground to brighten the coming weeks. Then, you can turn your focus to hardy annual and biennial seeds to sow in anticipation for next year's colour.

What to plant in August: My top 10 picks for late summer sowing and growing

Dahlias are an obvious choice when it comes to what to plant in August, as they will flower right up to the first frosts and several varieties bring added interest with bronze foliage. You can also rely on long-blooming salvias, astilbes, sunny rudbeckias and gaillardias, asters, sedums and heleniums.

Although the ground may be dry and the sun fierce right now, you can still plant in the soil as long as you keep everything well watered. Alternatively, if your beds and borders are already full, pop some plants in containers.

The importance of regular watering, especially with new plants, can't be stressed enough. It is crucial that plants are well hydrated as they get established as dehydration will hamper growth and weaken the plants.

1. Dahlias

Delicious dahlias are one of the most diverse and long-flowering perennials, guaranteeing you colour and interesting leaves from midsummer until late autumn. And August is a fine time to plant them out.

They are renowned for their glossy petals in a myriad of dazzling colors, as well as their huge range of shapes and styles, from little pom-pom heads to dinner plate-sized blooms.

An added bonus is that dahlias are as happy as part of your container gardening ideas as they are in the soil, as long as they are kept fed and watered. In fact, container-growing your plants makes it easier to move them into a greenhouse or porch in winter, when the top growth dies down and the tubers need storing in a tray of compost somewhere frost-free.

Top tip: Earwigs will munch through dahlia flowers and leaves. To catch them, fill a small plant pot with newspaper and upend it on a stick near your plants. Earwigs will hide in there during the day and you can collect them up and move them elsewhere (try not to kill them as they will eat aphids, an even worse pest).

2. Sedums

Fleshy-leaved sedums, also known as stonecrop and ice plants, produce mounds of pretty pink flowers over unusual, pale green stems and leaves. If you're thinking about what to plant in August, they're a great choice.

They love a sunny spot in well-drained soil and look amazing when several are grouped together at the front of a border. They make a good addition to the best drought-tolerant plants too, as once they are established they need little watering.

Plus, because they flower late in the year, often well into late autumn, they are an essential source of food for late-flying butterflies and bees.

Top tip: Leave the flowerheads attached through winter as they look beautiful covered in frost. Then cut them back in spring when next year's new growth is starting to show through.

3. Salvias

Many ornamental salvias will flower well into the fall, deep purple 'Amistad' being a key variety. So if you're wondering what to plant in August, these are a good choice.

There are more than 900 varieties and they do best on free-draining, sunny soil. Their leaves often give off a delicious herby scent when crushed between thumb and forefinger.

They also grow well in garden planter ideas, which is an added bonus in exposed, northern gardens as they can be moved indoors through winter to continue growing.

Hardy varieties are cut back hard in winter or early spring, while half-hardy plants (check the label when buying) are best cut back in autumn and overwintered in a frost-free greenhouse or heavily mulched with bark chippings, If you are not sure of the status of yours, leave pruning until the spring or drop me a not #e

They're easy to propagate, too. Just follow these simple steps:

1. Take cuttings in late summer or spring. Cut 4in (10cm) long pieces of non-flowering stem and strip away the lower leaves.

2. Dip each cut piece in hormone rooting gel and insert into a pot of gritty, watered cuttings compost.

3. Cover the pot with a clear plastic bag, then place in a cool greenhouse shielded from strong sunlight. They should be ready to pot on in three weeks.

4. Rudbeckias

Sunny rudbeckias can flower right the way through to October. They brighten the garden with their chunky, daisy-like blooms in fiery shades of yellow, red and orange – perfect if you love a hot-hued garden color scheme.

Also known as black-eyed Susan, they like a sunny spot and are one of the easiest plants to grow, with annual and biennial varieties such as double-petalled 'Cherokee Sunset' and 'Aries' started from seed in spring, and perennial 'Herbstone' and 'Goldsturm' planted at any time of year.

Mature clumps of perennial varieties that are four or five years old can be lifted and divided in spring or autumn.

Top tip: Most perennial rudbeckias come in shades of yellow, while annual varieties grown from seed generally have more varied coloring, with dramatic burnt oranges and reds often available.

5. Crocosmia