Question
Hi Edward - I live by the coast in Devon, south west uk.  I bought and planted a new wisteria in early spring.  It took off ok but as the season has worn on the foliage has become steadily more yellow and some leaves have now started going crispy brown round the edges although I can see tiny new buds appearing high on the stems.  We have sandy/poor soil so I have made sure I fed fortnightly with a general liquid garden fertilizer.  I've sprayed a couple of times with a general insectiside/fungicide. Any ideas would be gratefully received. Thanks and kind regards Jacky  

Answer
Hi Jacky,
How have you been watering the wisteria? With a sandy soil, you should be watering more often to help the roots take in as much water as possible. The wisteria sounds like it is in transplant shock due to the lack of a established root system. The plant will use all of it's stored energy in the first few months of being in it's new location to try to establish a expansive root system to replace the storage that it needs to maintain healthy growth.
Were you applying the fertilizer at full strength every two weeks? Depending on the analysis of the fertilizer, then you could have over dosed the root system with too much nitrogen. Some nitrogens are high in salts, which will "burn" the fine root hairs of the plant.
I would recommend that you increase the watering frequency and duration to help move any salts out of the root zone. You can prune back on it selectively to help the plant save on some energy expenditure. Try to stay away from fertilizing in the summer and reserve it for either the spring or fall.