how to grow clematis on flat shed roof

(Question)

See enclosed photo of garden shed. I have clematis plant growing up the brick wall (in pot). My shed has a flat felt roof, to which I cannot attach anything that will pierce it/put holes in it. What can I attach to the roof (which won’t damage roof) to allow clematis to climb across roof? Thanks for your assistance.

(Answer)

Dear gardener,

Thank you for contacting the Toronto Master Gardeners with your interesting question.

Clematis have an unique method of attaching themselves to freestanding structures. Their leaves have twining petioles that coil counterclockwise on wires, chain links fences or trellises as long as their leaves can twin around. They do enjoy full sun but require that their roots are kept cool, therefore it is always advisable to plant another perennial or shrub in front of it to keep their roots shaded.

You mentioned that your clematis is currently in  a pot (the picture does not show the entire area). As long as the pot is large enough (>24″w x 24″l) and it is made of a non porous material, it may be able to survive the winter, otherwise you will need to plant the clematis in the soil in order to winterize it. (Please refer to the following entry for directions: www.torontomastergardeners.ca/index.php/askagardener/overwintering-smal-lpatiosized-clematis-still-in-a-pot

In terms of the roof, it seems that the method you are currently using for it to climb up is working well. Sadly, we are not construction experts and therefore I hesitate to give you any advice on a felt roof as the delicate tendrils of the clematis could potentially go under the felt and damage it. You also need to follow your guarantee guidelines as they may be voided if growing something on it. May I suggest you ask your builder if  it possible for you to make a criss-crossed grid by nailing the sides and going across the width and length of the roof without damaging it. However, please be aware that this will not contain all the delicate leaves from going into undesirable places. I think that to be on the safe side, you may want to keep your clematis on the wall and away from the roof.

Also, do not forget about proper pruning time next year. See the following guidelines: www.torontomastergardeners.ca/index.php/askagardener/cleaning-up-clematis

Hope you found this in formation helpful.