[VeggieVirgin]

I planted an 84-section module with equal numbers of lupins, hollyhocks, kohl rabi and spring cabbage seeds. Nearly all of the veg. seeds have germinated (only two or three empty modules for each of them), but only about half of the lupins and two-thirds of the hollyhocks have come through.

All the seeds were planted in the same compost and have been treated the same.

Did I do something wrong, or are the germination rates for flowers just lower than for the veg. I planted?

[JayG]

Don't think you can generalise; your seeds have all been germinated under the same conditions and it probably suited some of them more than the others.

Either that or the seed viability was higher for some than others, possibly due to storage conditions, age of seed etc.

[mumofstig]

There is a minimum germination standard of 81% for veg seeds but no minimum standard for flowers.

Have a look here. The results are quite depressing when you think how much some flower seeds cost

Edited to correct wonky link 

[VeggieVirgin]

There is a minimum germination standard of 81% for veg seeds but no minimum standard for flowers.

I wish I'd known that, then I'd have planted more hollyhocks and lupins, and not so many cabbages.

(Only after I'd sown the cabbage seeds did it occur to me that we probably don't get through 21 cabbages per year - far less 21 all ready at the same time!)

[evie2]

I may be imagining this but some years ago I'm sure I watched a gardening program and they were advocating using the freezer or boiling water to help kick start seed germination. 
I'm think it was Beech Grove Garden