In the UK when people talk about planting 'annuals' they usually mean brightly coloured bedding plants, bought from the garden centre and planted in late spring to provide rich colour for much of the summer. For many, this is the main source of colour in their gardens, and is definitely the main contents of hanging baskets and pots. Colourful indeed, but also unfortunately, most Garden Centre annuals are completely useless for pollinating insects.
The term 'annuals' of course means any plant the sets seed readily and then dies out during the winter to be replaced by its seedlings next year. The sad truth about most bedding plants is that they are sterile and produced in vast numbers through 'hydroponics' in laboritories (sort of the plant version of cloning) and incapable of producing the pollen and nectar or setting seed. They have been bred for their colour and are now very far removed from their native species that would once have been part of the complex ecosystem. (I may be being cynical but I also wonder if the fact that they need to be replaced every year is not part of the business model to get us to buy new ones every year.)
But the world is still full of many true annuals, and although they may not all be as brightly coloured, during their brief life they are one of the most productive sources of nectar of all plant types. And, given the right conditions (and if weeding round them is carefully avoided) they set masses of seed and will reward you every year.
My Top annuals for bees are ...
1. Echium and borage; both members of the boraginaceae family and both have the handy habit of producing nectar all day long rather than just in the morning like most flowers. Apparently you can get more honey from an acre of borage or echium than any other plant that will flower in the UK.
2. Phacelia; grown in the UK mainly as either a green manure (where it is usually dug in before it flowers!!) or a game cover crop for grouse etc. Another member of the boraginaceae family and so easy to grow even in near-drought conditions and will support an incredibly wide variety of bee types.
3. Poppies - all types (and preferably multiple types which will extend the flowering period). Great for both pollen and nectar and have that fantastic habit of self-seeding anywhere
4. Forget me not - the humble little blue flowers that are often pulled out as weeds flower in April and are some of the first annuals to provide nectar after the tree blossom begins to fade. Dont week it out - keep at least a few patches as its gone by May allowing other things to grow over it.
5, Cornflowers - beautiful blue flowers that keep blooming from June through to September.
There are many others too so I would encourage everyone to stop wasting their money on bedding plants and invest on a much cheaper packet of 'real annual' seeds. Alternatively, Rosybee can provide annual plants including all of the above to get you started. We also sell perennial versions of both poppies and cornflowers and a range of perennials that is a great alternative for filling pots and window boxes.
In 2013 we did a trial of garden centre annuals and the results can be found here