The objective of this trial is to assess effectiveness of a range of commercially available seed mixes that are marketed as being good for bees. 2012 was the first year of this trial when we cleared over an acre of ground in our site and sowed 5 different seed mixes: 1. an 80% grass, 20% wildflower commercial mix to the DEFRA specification advised for field margin Environment Scheme
2. a ‘bumblebee’ mix of 100% flowers including borage and phacelia
3. a more expensive 30% wildflower mix with a much wider range of perennial wildflowers
4. a mix that is widely used and recommended in France
5. a ‘nectar and pollen’ 100% legume mix with lots of clovers – this was planted on a different and poorer soil to the others
Over the winter of 2012 and into 2013, we left the trial plots alone as the marketing information for most of them indicates that they should provide flower for 3 years. The exception to this was number 4, the 'French mix' which is purely annual and comes with instruction to clear and reseed each year. As we did not have access to a replacement seed batch we instead, collected as much seed as possible from the flowers and added both cornflowers and phacelia to approximate the original mix.
Our observations for 2013 are as follows:
Growth and weed suppression
The DEFRA mix, which is mostly grass was plagued by dock in the first year but now the grass has established and the dock reduced, but still almost no flower.All of the other mixes had allowed a range of perennial weeds to get established to some extent and this clearly impacted any annual flowers that relied on self-seeding to flower in the second year. The worst for this was the 'Bumblebee mix' that was the top performer in 2012 but relied on phacelia and borage, neither of which managed to reseed amongst the emerging nettles, grass and dock; this mix failed completely in the second year.
Each mix, except the Legume mix, flowered less in 2013 than in the first year and the mix of flowers changed too. The most dramatic change was observed in the wildfower mix where last year there was a weak showing of poppies, corncockles, and campion but this year it was dominated by a sea of oxeye daisy with a few occasional scabious and other flowers.
The change of flowers in the French mix may be partly because we estimated the seed mix quantities on re-sowing but overall, the phacelia was limited by the nettles, the cornflowers failed to germinate and so the dominant flower was the calendula which self-seeded successfully but is not a great draw for bees and tends to attract more hoverflies. (still valuable but not the objective)
The Legume mix, is based on 3 types of perennial clover that flowered weakly in the first year but in 2013 it managed to thrive inspite of the invasion of grass and thistles.
The chart shows that overall less bees were counted for each mix except the Legume mix, which was this years winner albeit from a poor range of choices. The phacelia component of the 'French mix' did flower well and briefly in June but was not supported by the other flowers that kept that mix going for longer last year.