Thursday, 4 October 2012

Late flowers for pollinators

We are in the middle of autumn now but some pollinators are still active such as butterflies, bumblebee queens, some hoverflies and honeybees. Especially the young bumblebee queens need to find enough nectar now to help them survive winter in hibernation. To provide nectar-rich plants well into autumn here are some suggestions what to plant:

All autumn flowering species of Michaelmas daisies (Aster spp.) are great for pollinators and look brilliant in the autumn garden. They need good soil and a sunny place to flower well.  Michaelmas daisies will flower until the first sharp frosts in November and attract bees, hoverflies and butterflies.

A Comma on Aster novae-angliae
A cuckoo bumblebee on Aster flowers

Great for pollinators, especially bees, are Ice plant (Sedum spectabile) and Stonecrop (Sedum telephium). Both plants should be planted in full sun and on well-drained soil as they will flop over in shade. They look pretty planted together with smaller Michaelmas daisies and ornamental grasses.

Another pretty plant attractive to pollinators is Sneezewort (Helenium autumnale). The plants will start flowering at the end of July and continue until well into autumn. In wetter years they might need staking so have supports ready before the plants start to flop over. Bees and butterflies like to visit the plants.

A honeybee visiting a Helenium flower

Black-eyed susan (Rudbeckia fulgida) is a pretty plant with yellow daisy flowers with a dark centre. The plant does not need a lot of care and can be planted in sun as well as half shade in normal garden soil. The flowers appear in August and last until the end of October. Bees and butterflies find the flowers irresistible.

Red bistort (Persicaria amplexicaule) has small bright red flowers and large, prominently veined ovate leaves. The plants can grow up to 1.20 m tall so need a bit of space. Plant in moist soil in full sun for the best flower display. Bees and hoverflies will visit the flowers but the plants seem to be especially attractive to wasps which like to drink the nectar.

The Small-headed sunflower (Helianthus micocephalus) is quite an impressive plant growing up to 1.80 tall. A popular cultivar is Helianthus `Lemon Queen` with pretty yellow daisy flowers on top of tall stems. The plants are flowering well into October and attract mostly bumblebees and butterflies.

Some Penstemons (for example Penstemon `Andenken an Friedrich Hahn`) will also flower well into autumn and attract mostly bumblebees which can access the long tubular flowers better than other pollinators. Penstemons are often short-lived perennials and some are not very winter-hardy so remember to take cuttings in autumn and provide some winter protection. They survive winter best if planted in very well-drained soil.

If you like Dahlias (Dahlia x hybrida) try to plant the single-flowered varieties (such as the various Bishop Dahlia varieties) and avoid the big showy double-flowers which provide no nectar. In mild areas (especially when planted in well-drained soil) you can leave the tubers in the ground over winter but if you have heavy soil or live in a colder area lift the tubers and put them in a box with just moist sand or wrap them in newspaper and store in your cellar or frost-free garage.

Verbena (Verbena bonariensis) is a very pretty plant but quite short-lived. The purple flowers, born in clusters on the top of tall slender stems, look beautiful in the late autumn sunshine and are loved by bees and butterflies. 

Quite a common plant and even sometimes a bit weedy, Red valerian (Centranthus ruber) is often overlooked. But if you cut back the first flush of flowers in summer it will flower a second time in autumn and provide much needed nectar for late-flying butterflies such as Small tortoiseshells and Painted ladies.

A very good late annual plant for pollinators is Cosmos (Cosmos bipinnatus and C. sulphureus). You need to sow the seeds in late spring and as the seedlings are not frost -hardy you need to keep them inside if you sow before May. The first flowers will appear in August and the plants will carry on flowering until the first sharp frosts in November. Cosmos flowers are a good food source for hoverflies, honeybees and bumblebees.

Cosmos sulphureus (orange) and C. bipinnatus (pink)

A late-flowering native plant which also looks quite attractive if planted in clusters is Devil`s-bit scabious (Succisa pratensis). It grows wild in boggy places, heathland and damp meadows but will also grow in your garden if you plant it in a sunny and damp place. You can grow Devil`s-bit scabious from seed or buy plants in some garden centres. Especially butterflies seem to like this plant as you can see in the picture below.

Meadow brown butterfly on a Devil`s-bit scabious

Mahonia (Mahonia x media) is a great plant for pollinators flowering from November until February with bright yellow scented flowers which are rich in nectar. Plant in a sheltered sunny place to attract winter-active bumblebees, hoverflies, honeybees, and wasps.

If you are after something special and live in a warm area you could try the Anchor plant (Colletia paradoxa) from South America. The Anchor plant grows as a big bush or small tree and has very spiny leaves. The plant is hardy down to a temperature of - 5C so only winter-hardy in mild areas. If you live in a colder area you could plant it in a large pot and overwinter the plant in a  greenhouse or conservatory. The white flowers open in autumn and have a sweet honey-like scent. The flowers are very attractive to honeybees; the plant I have seen in Kew Gardens, London was full of honeybees busily flying from flower to flower.

Have a look here for more pollinator-friendly plants flowering in late summer and autumn. Also have a look at the Plants for pollinators lists from the RHS.

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