I live in Toronto near LAke Ontario. I have had lots of problems growing many kinds of Clematis. One of the most common problems is the I get some blooms and then the leaves start to dry up, turn brown and die. What could be the cause. I have tried different locations, now trying south facing wall.when do I fertilize?
It sounds like your clematis may be suffering from a disease known as clematis wilt which causes wilting and blackening of the stems of large-flowered (early or late-summer-flowering) hybrid cultivars. Where wilting is seen on other types of clematis, the cause is more likely to be environmental problems, like drought stress as a result of growing in poor, shallow soil. Slug damage can also produce similar symptoms, where stems are partly eaten in the search for new foliage, collapsing as a result.
So, although wilting in clematis plants is often blamed on the fungal infection, unless it affects one of the more susceptible large-flowered hybrids it is most likely to be caused by environmental problems. Even on large-flowered hybrids, wilting of shoots is often the result of other problems such as pest (e.g. slugs and snails) or physical damage.
Clematis is a plant which, in the natural environment, prefers a deep and fertile soil in a moist and shaded habitat. However, in gardens, clematis are often planted in shallow dry soils in exposed sites, often close to buildings. In such circumstances they suffer from root stress which contributes to poor growth and what is loosely described as wilt.
Non-chemical control
- Try to create a suitable root environment by deep cultivation and mulching, to minimize root stress
- If fungal infection is suspected, cut out all wilted stems back to healthy (non-stained) tissue and promptly destroy the affected material to prevent it contaminating the soil. New healthy shoots may be formed at ground level
- Disinfect pruning tools to prevent spread of spores and avoid transferring infected plant and soil material to a new area
- Particularly susceptible cultivars include: Clematis ‘Henryi’, ‘Vyvyan Pennell’, ‘Mrs N. Thompson’, ‘Duchess of Edinburgh’, ‘William Kennett’, ‘Marie Boisselot/Madame le Coultre’, ‘Ernest Markham’. Clematis ‘Comtesse de Bouchaud’; C. ‘Jackmanii’ and C. ‘Nelly Moser’ are also susceptible
- Resistant cultivars and species include: Clematis Avant-garde, Bonanza, Confetti, C. alpina, C. montana, C. orientalis, C. viticella (which is tolerant rather than resistant), C. integrifolia, C. macropetala, C. tangutica
Chemical control
There are no chemicals available to treat clematis wilt.
For more in-depth information on the subject of clematis wilt see:
https://www.rhs.org.uk/advice/profile?PID=125
https://www.rhs.org.uk/advice/profile?PID=125
As to your question about fertilizing clematis — Clematis are heavy feeders. An established clematis will benefit from an application of organic slow-release fertilizer each spring and fall. So now is a great time to be fertilizing your clematis. Compost, either homemade or purchased is a good choice for this application. Younger plants may benefit from the addition of a liquid organic fertilizer applied when watering every six weeks during the growing season.
If you’d like to read more about caring for clematis, see the following link to Landscape Ontario’s advice on how to grow clematis.
https://landscapeontario.com/how-to-grow-clematis