Pink Flowers

Yarrow (Achillea millefolium)

Pink or white flowers. It is valuable for pollinators as it continues to flower right through to November or even later.

Sainfoin (Onobrychis viciifolia)

A tall plant with bright pink/red flowers which attract huge numbers of insects. It has nitrogen fixing properties and is a brilliant herbal remedy for grazing animals.

Centaury (Centaurium erythraea)

Its long-flowering clusters of small star-shaped pink flowers provide a reliable nectar source for a range of insects, especially butterflies, solitary bees and hoverflies from June to September. Its flowers close in wet weather to protect their pollen from being washed away. The blooms only open fully in bright sunshine and tend to close entirely by the afternoon or early evening.

Common Valerian (Valeriana officinalis)
A valuable plant as its fragrant nectar-rich flowers attract pollinators like bees and butterflies and its dense growth provides shelter for small wildlife and invertebrates.
Soapwort (Saponaria officinalis)
The flowers provide a valuable source of nectar and pollen and the plant’s fragrance attracts certain moth species at night. However, the saponins (the soap making compounds it produces) deter most insects from eating it and it is toxic to animals and humans. 
Field Bindweed (Convolvulus arvensis)
The nectar of the trumpet shaped flowers is popular with pollinators and its leaves are the food source for a number of moths including the White Plume Moth and  the Convolvulus Hawk Moth. The Four-Spotted Moth larvae specifically target field bindweed preferring its buds and flowers
Common Knotgrass (Polygonum aviculare)
Despite its name Knotgrass is not a grass but is related to the docks. Its pink flowers appear from May to October and its leaves are a food source for the Knot Grass Moth.
Hedgerow Cranesbill (Geranium pyrenaicum)
Its pinky-mauve flowers bloom from spring well into autumn and are highly attractive to bumblebees and other pollinators. It flowers from spring right into autumn so provides a food  source when other wildflowers have stopped flowering and its leaves are an essential food source for the caterpillars of the Brown Argus butterfly.
Hemp Agrimony (Eupatorium cannabinum)
Its frothy pink flower clusters appear from July to September and are very attractive to all kinds of insects, including butterflies like the Red Admiral and Small Tortoiseshell. Its common name comes from its leaves resemblance to hemp, although it is not related to it.