Last year in september my friend gave me one of her dahlia tubers as additional birthday present. This year I planted this tuber end of may and now it starts flowering.
It is a dahlia cultivar named 'Alva's Supreme' (I suppose) and beware - it needs lots of space in the plot. As fertilizer I used an long term store bought organic fertilizer and some mixed manure I made during the last years from garden cuttings, leaves, weeds and vegetable wastes - any kind of herbal organic material the garden and kitchen produces. The garden soil is sandy and acidic. In fact we are living on an extended terminal moraine covered by moors. Digging deeper you will find lots of big round stones - so called glacial erratics which can be pretty annoying if you try to dig up bigger and deeper holes as for planting bushes or trees. For gardening this soil is pretty bad and you have to choose the plants carefully. It makes not much sense to try to grow vegetables or you have to do raised bed gardening. Therefore most of the surrounding gardens are ornamental gardens only. But dahlias love this soil for sure.