In spring this year we planted 5 different seed mixes which are marketed as being good for pollinating insects:
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
Now in September I can report the first years results. As you would expect from the range above the results are very mixed. Weeds that we failed to fully irradicate first have been the main challenge which is very common story with seed mixes. We had sprayed the area with a general weedkiller the previous autumn so our perennial weed has not been too bad except for the nettles; our challenge has been germination of both annual and perennial weed from seeds we exposed when we ploughed in spring. We should have waited longer for that to germinate but then you loose the ideal time to sow the seeds you want. The lesson is to fully prepare the ground in autumn or sow later in early summer after the weed seed has sprouted and been removed.
a. Growth and weed suppression
Mixes 1, 2 and 4 all grew quickly which reduced the content of other species of plants. The most effective at weeds suppression appeared to be mix 2, the bumblebee mix, as the phacelia grows very fast and then the clovers pack out any remaining space. The wildflower mix has the most weed as even the grass elements are slower to get established. The sellers have deliberately chosen slower growing grass types to avoid the perennial wildflowers being crowded out; the problem is that allows other weed plenty of opportunity to get in there. This patch now looks terrible but we will leave it to see how if fairs over time.
The mixes with a high content of annual flowers not only won the war against the weeds but also produced the most flower this year. The two with the most flower are the 4, the French mix (pictured above in Sept) and 2, the bumblebee mix.
The least flower was produced by mix 1, the DEFRA spec, which is only now producing a few flowers from 10% the clover content but the overall effect is 99.9% green.
The French mix has been the most dramatic and colourful and has changed every month going from purple phacelia in June, through blue cornflowers in July and on to yellow calendula and coreopsis in August. However the phacelia, then borage, then clover content of the bumblebee mix has been more muted in shades but a very similar flower density up to August.
c. Bee attraction
Both the Bumblebee and French mixes did very well for insect attraction. In part this was because they both contained phacelia which was clearly the winning plant for be density. Our method of assessing is the pick a sunny day, at times between 12 and 3 pm and then count bees per square meter. The full results were as follows: