Complete guide to green alkanet

Large bristly leaves and small, open, five-petalled flowers, borne in open clusters, are the key features of green alkanet. Leaves grow up to 40cm long, are oval in shape with pointed tips, and occasionally have white speckles. Both leaves and plant stems are covered with bristly hairs. The leafy growth may be semi-evergreen in mild winters, though more usually the whole plant is herbaceous, dying back in autumn and starting regrowth early in spring. Green alkanet grows up to a metre in height and spreads outwards by way of runners to form wide clumps.

Plants that green alkanet gets mistaken for

Green alkanet belongs to the borage (Boraginaceae) family, and its large bristly leaves and blue flowers mean that it's often confused with true borage (Borago officinalis). However, despite being a similar colour, the flowers are different – borage flowers have tapering petals that give the flowers more of a star shape, and the centre of the flower is dark blue and raised. It also has dark blue sepals behind the petals. Borage flowers are commonly used to decorate summer drinks and the flowers of green alkanet can be used as a substitute for borage.

Comfrey (Symphytum) also belongs to the Boraginaceae family and has large, hairy green leaves that look similar to green alkanet, although green alkanet is not the same as comfrey. Comfrey has white or purple, bell-shaped flowers, in contrast to the blue, open flowers of alkanet.

Is green alkanet a weed?

Because green alkanet is a vigorous perennial, often escaping from gardens to naturalise in the wild, or smothering neighbouring plants with its large leaves and spreading growth, it is sometimes considered a weed. However, the concept of plants as ‘weeds’ is a loose one and depends on where green alkanet is growing.

Should I remove green alkanet?

In wilder parts of the garden where green alkanet can spread without danger of swamping other plants, it makes excellent ground cover and bears flowers for many months – providing food for a wide range of bees while its leaves are eaten by caterpillars of the scarlet tiger moth. Green alkanet has many benefits for wildlife.

How to get rid of green alkanet

Green alkanet forms deep tap roots which need to be completely dug out in order to get rid of the plants. Severed roots will survive if added to a compost heap so dispose of by them by rotting them down in plastic bags or buckets of water. Alternatively dispose of them responsibly at your local tip. Green alkanet often self-seeds freely so cut back after flowering to prevent seeding, and restrict its spread. As with all weeds, removing them when plants are small is much easier than leaving the plants to become large and established.

Wear gloves when handling green alkanet, as the bristly leaves may cause skin irritations.

Value to wildlife

Green alkanet is valuable to wildlife in several ways. Bees, along with other pollinators, feed on the flowers which are rich in nectar, while caterpillars of the scarlet tiger moth feed on the foliage. Large leaves and dense growth provide shelter for small mammals. Green alkanet is a useful plant for wildlife in the right places, away from garden borders and growing in wilder or woodland spots.

However, green alkanet is a vigorous, spreading, and deep-rooted plant that has potential to be invasive and may smother neighbouring plants that are also beneficial to wildlife, reducing the biodiversity of a garden.

Frequently asked questions

Is green alkanet poisonous to dogs and cats?

Green alkanet is not toxic to dogs and cats. If consumed in large quantities – which is unlikely, as the growth is bristly and unpalatable – it may cause mild gastric upset.

What is green alkanet used for?

Green alkanet is an excellent wildlife plant and is useful to grow in difficult places where few other plants thrive. The flowers are edible and useful for decorating salads, drinks and sweet dishes. A red dye can be extracted from the roots, though this dye is said to be inferior in quality compared to others.