Posted: 14/02/2016 at 21:55
the Bishop is excellent. Apart from the flowers the foliage is dark purple and good as a foil for other plants. From one plant I now have several large plants.....some are in containers. They grow 80 cm tall plus, do not need support and remain bushy in pots. I mix dried manure with the compost plus fish blood and bone in early spring and this is sufficient for whole season.
to reduce height pinch out main shoots a couple of times. Be prepared to dead head regularly to minimise weight on stems ..if windy there
secret to large dahlias, in my experience, is to start them off early so I would pot them up now or asap in dry compost and start watering when shoots are seen