[tedlester]

Hello.  I have been an allotment holder for well over 55 years but since converting to organic gardening I have had a problem with Brassicas. I fertilise my ground with home made compost and well rotted stable manure. I supplement this with Comfrey and potash, and I always make sure that the ground is fairly well compacted. But with the exception of Brussell sprouts, Cauliflowers, Brocolli of all types and cabbages they all only produce small heads which are loose and not hearted up. What am I doing or not doing to produce first class crops to rival the professional growers? 

                                                                          Ted Lester, Shoeburyness, Essex.

[Goneterseed]

It sounds as if you're spoiling them with too much potash. A cheap soil tester will possibly point to the soil needing a good aplication of lime to raise the PH level. It needs to be somewhere between 6.5 and 7.5 for brassicas. A nitrogen based feed will do them a lot more good than comfrey, I'd save that for spuds and fruiting crops.
If the heads are opening up, (blowing), it could be that they are rocking in the wind and damaging the small hairy roots near to the base. A short cane would help this.

[tedlester]

Thanks everyone for the tips about improving my Brassicas, I shall stop feeding them with Comfrey. My Dad always used to top feed with a dressing of soda granules and had good results. I shall stop the Comfrey feeds and increase the watering.

[neatntidy]

If your organic try stinging nettle tea. Good source of nitrogen. Make it same as comfrey. I stew both in the wife's old tights in a sealed container