I'm putting up a trellis to screen an oil tank and would like to use clematis as the climber to mask the structure. The site receives sun at all times except the evening.
As a complete novice, advice on pruning as well as variety would be greatly appreciated. Obviously a species with a long flowering period would be a bonus.
Longest flowering varieties are Viticella but they require pruning back to ground if you want the best flowers which means first half of the year is about re-covering the thing you are trying to disguise.
I'd opt for a Montana. They flower in abundance around this time of year, with gorgeous foliage to follow. They are vigorous and can be left to get on with it
No pruning required so they form a thicket which leafs up abundantly in spring, hey presto, no ugly tank for nine/ten months of the year
Just re-read your post, consider the size of your trellis, Montana need strong support
If your trellis is the light kind don't use Montana or the trellis will suffer
If your tanks dbl bunded you may find a solution is to wire across the top removable part and not bother with a trellis (not the bottom or your defeating the point of the bund). We let Clematis Niobe grow across ours and let delphiniums and verbena bonariensis grow in front. Its not a winter early spring solution as Niobe needs cutting back and obviously the delphs and Verbena die back though that means the tanks easy to inspect..
We have a very prickly row of Berberis growing all around ours, there is often someone ready to cut the tanks and syphon out the oil in the country areas..
I dont think anyone would like to try it on ours. The Police actually recommended it, they said that they would get some DNA from it!
Clematis montana does the job as Wintersong says and you will need to prune one back ruthlessly immediately after flowering to control its size unless you don`t mind it being rampant. You could grow annual climbers to give flower power among its foliage for the rest of the summer months, sweet peas, ipomoea, tropaeolum etc, all easy from seed.
Thanks to all for the speedy replies. I think I'll go with Wishbone's solution as I can grow sweet peas!!