F2 means the parents were F1 [specially bred] but have been pollinated by bees or wind in the open and are thus one stage further from the bred ones.
Because the seeds are result of open pollination the chances of being liked by bees are high

Thank you grandad gar. I’ll order them in that case. Thanks again.

as a general rule single flower forms rather than double petal form of any plant is better for pollinators. most of the Achillea are single flower forms though there is a cluster of flowers in the flower head. Cloth of gold is a lovely one. in my experience bees seem to prefer the yellow, cream and white flowers better than the reds & purples.
as said F2 just means a second generation of offspring. in human terms grandchildren are your F2 generation.

Just as an aside, only sow a few seeds as in my experience they will germinate like weeds; which is what they are (Yarrow).

Now now Jimmy only weeds if you don't want them ;o)

think of yarrow as a beautiful Britsh native which of course it is. We once had a wild yarrow with white flowers with a pink edge. very pretty until OH used feed and weed on the grass.

What I was intimating was that they germinate so readily that it's best to sow just a few. Many years ago, I bought a packet of the Cloth of Gold variety and decided to sow the whole packet of seeds. Virtually everyone germinated so what can you do with a hundred tiny seedlings when you don't have a greenhouse?

I realised that Jimmy, I was only gently teasing you.

don't you find that if you want 6 plants and sow only 6 none grow. if you then sow 12 all grow. so contrary. :o)

The pink ones are varieties of Achillea millefolium, which spreads widely by underground stems. Keep your trowel handy, because it can become a thug.

Many thanks to yiu all next years seeds are on the go cheers