Autumn Dahlias are magnificent at this time of year, they are fantastic border fillers to put in gaps or areas of the garden where there is little colour or fading vegetation.
Nancy Brown: Flatford Wildlife Garden Visitor Centre & Bishop of llandaff dahlias in bloom.
It is the Single-flowered Dahlias that are beneficial to our bees, butterflies and other garden pollinators because they expose the centre of the plant where the pollen and nectar can be accessed. Cactus, ball and waterlily dahlias have their centres covered by petals so are not beneficial to pollinators so when choosing some for your garden, do try and include some single flowered varieties. You can even buy specific bee & butterfly dahlia collections online for example from the Royal Horticultural Society.
We can easily see the pollen in the centre of many open single petal flowers like Japanese anemones, Asters, Echinaceas, Rudbeckias and dahlias. The pollen is produced by and "waits" on the male part of the flower called the anther at the end of the filament (together, they are referred to as the stamen) where either pollinators collect it for food, or the wind takes it to pollinate with other plants. Bees drink sweet nectar as essential carbohydrates needed for every day energy and eat pollen containing proteins.
The part of the plant that produces the nectar is called the nectaries which can be in various places depending on the species, deep inside the flower. The nectar actively entices the pollinators with a sweet drink so that they will hopefully brush against the pollen and distribute it on the female parts of a plant for reproduction. You can see a variety of videos online detailing the reproductive male and female parts of a flower to clarify the parts for example here with Science Sauce.
Wisconsin pollinators online tell us an interesting fact about the sweetness of nectar stating that it ranges in sweetness "from as little as 8% to as high as 50%. The concentration of sugar in Coca-cola is only 10%, for comparison. Although nectar is known for its sweetness, it also includes additional compounds such as vitamins, oils, amino acids and others."
Knowing a little bit about how pollination occurs is useful knowledge to the wildlife gardener in helping us to understand which plants are the most beneficial to our garden pollinators. So if you're looking for some additional striking autumn colour, single flower dahlias could be just the thing for you and the bees.
Garden's illustrated feature the favourite dahlias of plant designers which include several single varieties but you may find something at your local garden centre with bees already buzzing around the blooms. (This always sways me into making a purchase!)
For more inspiration on wildlife gardening, the Flatford Wildlife Garden, is currently open every day until October from 10.30am – 4.30pm. Entrance to the garden is free and well-behaved dogs on leads are welcome. Car parking is £5 at the Flatford National Trust car park and this gives you access to the stunning countryside walks around Flatford and Dedham Vale in Constable Country.