Plants with September Flowers – A Gardening Guide

It is too early for winter flowers but too late for summer flowers. However, the right plants should see plenty of bright September flowers around, carrying the garden through until October when the winter flowers will start to take centre stage. Make the most of some of the taller September flowering plants which will add lots of interest to your garden whilst other plants are fading. For a seamless transition from summer to autumn planting more ideas are contained in Plants with August Flowers – A Gardening Guide.

September Flowering Shrub

Cerastostigmawillmottianum Forest Blue ‘Lice’ (Chinese plumbago) reaches a height of 1 m and a spread of 1.5 m. It is fast-growing and brings some welcome colour to the garden at this time of year. Vivid cobalt-blue flowers appear from August to October before the leaves turn red and drop.

Tall September Flowers

A tall September flowering plant to try is Centaurea atropurpurea (knapweed). Its ruby red thistle-like flowers are perched atop tall, upright stems from June until October. The foliage is feathered and because of its height of up to 1.5 m and 75 cm across it looks good towards the back of a border, or, for a more natural, wilder look, try it with ornamental grasses. In winter its seedheads provide interest in the garden, so resist the temptation in autumn to remove the dead flower heads.

The long-lasting white flower heads of Ageratina altissima ‘Chocolate’ (eupatorium) look lovely above the bronze foliage of this clump-forming plant. Attractive to butterflies and bees and reaching a height and width of 1.5 m it looks good planted with grasses which can show of its chocolate foliage.

Medium Height September Flowers

Agastache (hyssop) will give you blooms from July to October. There are several varieties with different colours. They are great for adding height to a border, reaching around 90 cm tall and 40 cm wide. They have spires of tiny, long-lasting bottlebrush-like flowers. Try ‘Black Adder’ with its violet flowers and aromatic foliage either in a Mediterranean or prairie scheme with long grasses. It is also a popular flower for butterflies and bees, as is the next flower:

Clusters of dark blue flowers, long stems and aromatic pointy foliage characterize Caryopteris x clandonensis ‘Heavenly Blue’ (bluebeard). This September flowering plant has an upright habit, growing to around 1 m x 1m and is another one for the butterflies and bees.

Chrysanthemum ‘Mary Stoker’ (chrysanthemum) produces large sprays of single daisy-like flowers in an apricot colour. They are fast growing to a height of 75 cm x 45 cm, and look equally as good with other flowering plants as well as grasses.

Small Height September Flowers

Tricyrtis formosana ‘Dark Beauty’ (toad lily) has purple-spotted star-shaped flowers in August and September and dark green leaves. Its unusual markings stand out in a woodland garden or shady border. Grows to 50 cm x 30 cm.

September flowers will extend your summer season through autumn to the onset of winter. For ideas on winter planting to follow-on from these September plants please see the article Plants with October Flowers – A Gardening Guide.