Posted: 04/08/2016 at 13:28
Clematis are hungry, thirsty plants. I buy mine as 3' high, multi-stemmed plants in tall, narrow pots from a specialist grower. I then plant them in a good quality loamy compost for flowering plants in pots twice as deep and wide, if not more, and keep them there for at least a whole year so they can develop a good, strong root system before they go out into the hurly burly of life in the borders. I train them on willow stems and keep them pruned after flowering and move them to a frost free place for winter so their roots are safe.
Every time they are potted on or planted out they go in about 4" deeper than they were before as this encourages extra shoots. Whether they are in pots or in the ground they get a spring boost of slow release fertiliser and occasional liquid tonics of tomato food.
When I do plant them out I do it in early spring and cut all stems back so that I can put an upturned terracotta plant pot over them to protect the stems from hoeing accidents. They then get a good feed, a very good watering and a few slug pellets to protect new growth.
It's worth all the patience to get a really good, strong plant.