By Sjw
gloucestershire,
United Kingdom 
I’ve not had much success with climbers planted against my house, a wisteria took ages to flower and the flowers were an insipid colour not like when I bought it in flower, I planted two climbing roses whose both blooms seems paler in colour than they should be. Also an actinidia kolomikta whose pink leaves seemed to fade to a white. These have been over several years and only now am I wondering can your house leach out something that damages plants. It’s a barn conversion that was done over 20 years ago. Nothing seems to thrive.
3 Jun, 2020
Answers
How close to the wall do you plant new climbers?
3 Jun, 2020
I plant about 30cm away from wall with added compost and John innes 3 and some fish blood and bone. It dry weather plants are watered regularly
3 Jun, 2020
A foot away is the minimum, so that's not the problem
3 Jun, 2020
How much sun are they getting there? Are there shade trees nearby? A little too much shade can slow growth and make colors paler.
3 Jun, 2020
Shade not a problem, the front of the house is south facing
3 Jun, 2020
Hmm...occasionally, I have seen a potash deficiency cause loss of pigment. You might try applying washed seaweed. Lava sand--i.e., fine volcanic cinders--might also help, if they are available, there.
3 Jun, 2020
I wonder if there is insufficient soil depth and therefore not enough water or root run for them to do really well. All mortar will leach a little bit of alkaline salts but after 20 yrs I wouldn't have thought it would have much effect.
3 Jun, 2020