3 gardening questions-black eye susan, trumpet vine, delphiphiums?

Question

my black eye susans get black spots on their leaves and the leaves die off, can you tell me what this is and what to do about them.

my 7 trumpet wines are 3 years old and have yet to flower, is this normal and what can I do to get them to flower. Also after delphiums bloom are you suppose to cut them down and if so how far.

Thank you

Answer 1

Yes Thunbergia does get black spot in warm humid weather and also red spider mite sometimes. Black spot is a funghal disease, the best control is prevention which means ensuring your plants are healthy. feed with sulphate of potash to boost the immune system. You can buy fungicides of course.

Trumpet vines can take a while to flower but it's worth it :-) shouldn't be long now.

Yes cut delphs down to ground level when flowering is finished unless you want to collect seed or see if it'll naturalise in the garden. In which case you'll have to wait until the seed pods are dry.

Answer 2

dont know about the others, but i can tell you about trumpet vines.  i had some and it took 5 years before they flowered.  i wish i had never planted it though because it spread by underground runners and they pop up everywhere.  i have had new plants come up 20ft from the original.  now i cant get rid of it.  its all but impossible to kill, and forget digging it up.  even the smallest piece of root will start the plant over again.  big mistake planting that thing.  fortunately its not the only mistake i ever made, so i am used to it.