Green manures are ‘crops’ which are sown to cover bare soil and do a number of jobs depending on the species like protecting soil, storing nitrogen or mining minerals. As I was writing about solitary bees last week it got me thinking about plants for bees which is when green manure Phacelia tanacetifolia popped into my head.
Phacelia is a quick growing hardy annual that is used for covering soil but also has an extensive root system which helps improve soil structure. It will germinate at low temperatures and will flower 6-8 weeks after sowing so is good to sow now. The flowers are very attractive to pollinating insects including honey bees, bumble bees, solitary bees and hoverflies so it will be a valuable end of season food source.
I don’t know enough about this yet but research has shown that many wildflower mixes we sow result in an increase in honey and bumble bee species but aren’t showing the same increases for solitary bees. Phacelia, however is attractive to this most important (and most under threat) species. In Germany Phacelia is known as Bienen-freund (bee’s friend) and is also grown alongside crops to attract hoverflies who keep aphid populations down.
Belonging to the borage family (another excellent pollinating plant) Phacelia will self seed just like borage but generally doesn’t become invasive as seedlings are easily hoed off. You can sow from March to September but if you are looking for flowers this season you are best to sow asap, the flowers will persist up to the first frost.
New seedlings are generally ignored by slugs and once grown will produce attractive ferny foliage topped off with the very pretty purple flowers pictured. The pollen is bright blue in colour and can be clearly seen in the pollen sacks of honey bees who have been visiting the plants which is fun to see. Phacelia is part of the Hydrophyllaceae family so fits into any bed in a crop rotation plan.
The beautiful photos in this article are not my own and have been borrowed from the brilliant Urban Pollinators blog (http://urbanpollinators.blogspot.com) which I am very grateful for. The images include the common carder bee (header and above), the red-tailed bumble bee (below) and a hoverfly.
That’s it for now, see you next week!