Posted: 12/10/2014 at 13:00
Clematis are hungry an dthirsty plants so the first thing to do is to plant it in the ground or in a much bigger pot - 60cms minimum. The white mould is a sign of stress from lack of moisture and probably food as it will have exhausted the supplies in that compost.
Plant it 3 or 4 inches deeper than it is now as this will encourage new shoots to form and provide extra flowers next year. If in a pot, give it the best compost you can afford - John Innes no 3 and give it a mulch of pebbles, chipped bark or expanded clay pellets to retain moisture and stop weeds growing. Give it regular liquid feeds of rose or tomato fertiliser from March to July or August.
If in the ground, mix some well rotted manure or garden compost in the hole to provide moisture retention and food. Scatter wildlife friendly slug pellets around it every week fromm Valentine's Day as they love the new shoots. Give it a handful of slow releas clematis food in spring and occasional tonics of liquid rose or tomato food.
Prune your clematis hard back to about 9 " or the lowest pair of buds on each stem next spring in Feb or March depending on how cold you are. Do not prune during a frosty period.
Give it a decent sized obelisk or trellis to grow up as it will get much bigger next year.